npm run lint:fix

35 files changed, 253 insertions, 253 deletions

diff --git a/test/background/infrastructures/MemoryStorage.test.ts b/test/background/infrastructures/MemoryStorage.test.ts
index 95d3780..ccdf9f0 100644
--- a/test/background/infrastructures/MemoryStorage.test.ts
+++ b/test/background/infrastructures/MemoryStorage.test.ts
@@ -2,7 +2,7 @@ import MemoryStorage from 'background/infrastructures/MemoryStorage';
 
 describe("background/infrastructures/memory-storage", () => {
   it('stores values', () => {
-    let cache = new MemoryStorage();
+    const cache = new MemoryStorage();
     cache.set('number', 123);
     expect(cache.get('number')).to.equal(123);
 
@@ -14,7 +14,7 @@ describe("background/infrastructures/memory-storage", () => {
   });
 
   it('returns undefined if no keys', () => {
-    let cache = new MemoryStorage();
+    const cache = new MemoryStorage();
     expect(cache.get('no-keys')).to.be.undefined;
   })
 
@@ -23,22 +23,22 @@ describe("background/infrastructures/memory-storage", () => {
     cache.set('red', 'apple');
 
     cache = new MemoryStorage();
-    let got = cache.get('red');
+    const got = cache.get('red');
     expect(got).to.equal('apple');
   });
 
   it('stored cloned objects', () => {
-    let cache = new MemoryStorage();
-    let recipe = { sugar: '300g' };
+    const cache = new MemoryStorage();
+    const recipe = { sugar: '300g' };
     cache.set('recipe', recipe);
 
     recipe.salt = '20g'
-    let got = cache.get('recipe', recipe);
+    const got = cache.get('recipe', recipe);
     expect(got).to.deep.equal({ sugar: '300g' });
   });
 
   it('throws an error with unserializable objects', () => {
-    let cache = new MemoryStorage();
+    const cache = new MemoryStorage();
     expect(() => cache.set('fn', setTimeout)).to.throw();
   })
 });
diff --git a/test/background/repositories/Mark.test.ts b/test/background/repositories/Mark.test.ts
index 167e512..625f11d 100644
--- a/test/background/repositories/Mark.test.ts
+++ b/test/background/repositories/Mark.test.ts
@@ -9,7 +9,7 @@ describe('background/repositories/mark', () => {
   });
 
   it('get and set', async() => {
-    let mark = { tabId: 1, url: 'http://example.com', x: 10, y: 30 };
+    const mark = { tabId: 1, url: 'http://example.com', x: 10, y: 30 };
 
     repository.setMark('A', mark);
 
diff --git a/test/background/usecases/NavigateUseCase.test.ts b/test/background/usecases/NavigateUseCase.test.ts
index ecbf888..48a1c5b 100644
--- a/test/background/usecases/NavigateUseCase.test.ts
+++ b/test/background/usecases/NavigateUseCase.test.ts
@@ -16,10 +16,10 @@ describe('NavigateUseCase', () => {
 
   describe('#openParent()', async () => {
     it('opens parent directory of file', async() => {
-      var stub = sinon.stub(tabPresenter, 'getCurrent');
+      const stub = sinon.stub(tabPresenter, 'getCurrent');
       stub.returns(Promise.resolve({ url: 'https://google.com/fruits/yellow/banana' }))
 
-      var mock = sinon.mock(tabPresenter);
+      const mock = sinon.mock(tabPresenter);
       mock.expects('open').withArgs('https://google.com/fruits/yellow/');
 
       await sut.openParent();
@@ -28,10 +28,10 @@ describe('NavigateUseCase', () => {
     });
 
     it('opens parent directory of directory', async() => {
-      var stub = sinon.stub(tabPresenter, 'getCurrent');
+      const stub = sinon.stub(tabPresenter, 'getCurrent');
       stub.returns(Promise.resolve({ url: 'https://google.com/fruits/yellow/' }))
 
-      var mock = sinon.mock(tabPresenter);
+      const mock = sinon.mock(tabPresenter);
       mock.expects('open').withArgs('https://google.com/fruits/');
 
       await sut.openParent();
@@ -40,10 +40,10 @@ describe('NavigateUseCase', () => {
     });
 
     it('removes hash', async() => {
-      var stub = sinon.stub(tabPresenter, 'getCurrent');
+      const stub = sinon.stub(tabPresenter, 'getCurrent');
       stub.returns(Promise.resolve({ url: 'https://google.com/#top' }))
 
-      var mock = sinon.mock(tabPresenter);
+      const mock = sinon.mock(tabPresenter);
       mock.expects('open').withArgs('https://google.com/');
 
       await sut.openParent();
@@ -52,10 +52,10 @@ describe('NavigateUseCase', () => {
     });
 
     it('removes search query', async() => {
-      var stub = sinon.stub(tabPresenter, 'getCurrent');
+      const stub = sinon.stub(tabPresenter, 'getCurrent');
       stub.returns(Promise.resolve({ url: 'https://google.com/search?q=apple' }))
 
-      var mock = sinon.mock(tabPresenter);
+      const mock = sinon.mock(tabPresenter);
       mock.expects('open').withArgs('https://google.com/search');
 
       await sut.openParent();
@@ -66,12 +66,12 @@ describe('NavigateUseCase', () => {
 
   describe('#openRoot()', () => {
     it('opens root direectory', async() => {
-      var stub = sinon.stub(tabPresenter, 'getCurrent');
+      const stub = sinon.stub(tabPresenter, 'getCurrent');
       stub.returns(Promise.resolve({
         url: 'https://google.com/seach?q=apple',
       }))
 
-      var mock = sinon.mock(tabPresenter);
+      const mock = sinon.mock(tabPresenter);
       mock.expects('open').withArgs('https://google.com');
 
       await sut.openRoot();
diff --git a/test/background/usecases/filters.test.ts b/test/background/usecases/filters.test.ts
index bdfb0be..90541ff 100644
--- a/test/background/usecases/filters.test.ts
+++ b/test/background/usecases/filters.test.ts
@@ -3,15 +3,15 @@ import * as filters from 'background/usecases/filters';
 describe("background/usecases/filters", () => {
   describe('filterHttp', () => {
     it('filters http URLs duplicates to https hosts', () => {
-      let pages = [
+      const pages = [
         { url: 'http://i-beam.org/foo' },
         { url: 'https://i-beam.org/bar' },
         { url: 'http://i-beam.net/hoge' },
         { url: 'http://i-beam.net/fuga' },
       ];
-      let filtered = filters.filterHttp(pages);
+      const filtered = filters.filterHttp(pages);
 
-      let urls = filtered.map(x => x.url);
+      const urls = filtered.map(x => x.url);
       expect(urls).to.deep.equal([
         'https://i-beam.org/bar', 'http://i-beam.net/hoge', 'http://i-beam.net/fuga'
       ]);
@@ -20,12 +20,12 @@ describe("background/usecases/filters", () => {
 
   describe('filterBlankTitle', () => {
     it('filters blank titles', () => {
-      let pages = [
+      const pages = [
         { title: 'hello' },
         { title: '' },
         {},
       ];
-      let filtered = filters.filterBlankTitle(pages);
+      const filtered = filters.filterBlankTitle(pages);
 
       expect(filtered).to.deep.equal([{ title: 'hello' }]);
     });
@@ -33,15 +33,15 @@ describe("background/usecases/filters", () => {
 
   describe('filterByTailingSlash', () => {
     it('filters duplicated pathname on tailing slash', () => {
-      let pages = [
+      const pages = [
         { url: 'http://i-beam.org/content' },
         { url: 'http://i-beam.org/content/' },
         { url: 'http://i-beam.org/search' },
         { url: 'http://i-beam.org/search?q=apple_banana_cherry' },
       ];
-      let filtered = filters.filterByTailingSlash(pages);
+      const filtered = filters.filterByTailingSlash(pages);
 
-      let urls = filtered.map(x => x.url);
+      const urls = filtered.map(x => x.url);
       expect(urls).to.deep.equal([
         'http://i-beam.org/content',
         'http://i-beam.org/search',
@@ -52,7 +52,7 @@ describe("background/usecases/filters", () => {
 
   describe('filterByPathname', () => {
     it('remains items less than minimam length', () => {
-      let pages = [
+      const pages = [
         { url: 'http://i-beam.org/search?q=apple' },
         { url: 'http://i-beam.org/search?q=apple_banana' },
         { url: 'http://i-beam.org/search?q=apple_banana_cherry' },
@@ -60,12 +60,12 @@ describe("background/usecases/filters", () => {
         { url: 'http://i-beam.org/request?q=apple_banana' },
         { url: 'http://i-beam.org/request?q=apple_banana_cherry' },
       ];
-      let filtered = filters.filterByPathname(pages, 10);
+      const filtered = filters.filterByPathname(pages, 10);
       expect(filtered).to.have.lengthOf(6);
     });
 
     it('filters by length of pathname', () => {
-      let pages = [
+      const pages = [
         { url: 'http://i-beam.org/search?q=apple' },
         { url: 'http://i-beam.org/search?q=apple_banana' },
         { url: 'http://i-beam.org/search?q=apple_banana_cherry' },
@@ -73,7 +73,7 @@ describe("background/usecases/filters", () => {
         { url: 'http://i-beam.net/search?q=apple_banana' },
         { url: 'http://i-beam.net/search?q=apple_banana_cherry' },
       ];
-      let filtered = filters.filterByPathname(pages, 0);
+      const filtered = filters.filterByPathname(pages, 0);
       expect(filtered).to.deep.equal([
         { url: 'http://i-beam.org/search?q=apple' },
         { url: 'http://i-beam.net/search?q=apple' },
@@ -83,7 +83,7 @@ describe("background/usecases/filters", () => {
 
   describe('filterByOrigin', () => {
     it('remains items less than minimam length', () => {
-      let pages = [
+      const pages = [
         { url: 'http://i-beam.org/search?q=apple' },
         { url: 'http://i-beam.org/search?q=apple_banana' },
         { url: 'http://i-beam.org/search?q=apple_banana_cherry' },
@@ -91,12 +91,12 @@ describe("background/usecases/filters", () => {
         { url: 'http://i-beam.org/request?q=apple_banana' },
         { url: 'http://i-beam.org/request?q=apple_banana_cherry' },
       ];
-      let filtered = filters.filterByOrigin(pages, 10);
+      const filtered = filters.filterByOrigin(pages, 10);
       expect(filtered).to.have.lengthOf(6);
     });
 
     it('filters by length of pathname', () => {
-      let pages = [
+      const pages = [
         { url: 'http://i-beam.org/search?q=apple' },
         { url: 'http://i-beam.org/search?q=apple_banana' },
         { url: 'http://i-beam.org/search?q=apple_banana_cherry' },
@@ -104,7 +104,7 @@ describe("background/usecases/filters", () => {
         { url: 'http://i-beam.org/request?q=apple_banana' },
         { url: 'http://i-beam.org/request?q=apple_banana_cherry' },
       ];
-      let filtered = filters.filterByOrigin(pages, 0);
+      const filtered = filters.filterByOrigin(pages, 0);
       expect(filtered).to.deep.equal([
         { url: 'http://i-beam.org/search?q=apple' },
       ]);
diff --git a/test/background/usecases/parsers.test.ts b/test/background/usecases/parsers.test.ts
index f3a64eb..d08de0d 100644
--- a/test/background/usecases/parsers.test.ts
+++ b/test/background/usecases/parsers.test.ts
@@ -3,13 +3,13 @@ import * as parsers from 'background/usecases/parsers';
 describe("shared/commands/parsers", () => {
   describe("#parsers.parseSetOption", () => {
     it('parse set string', () => {
-      let [key, value] = parsers.parseSetOption('hintchars=abcdefgh');
+      const [key, value] = parsers.parseSetOption('hintchars=abcdefgh');
       expect(key).to.equal('hintchars');
       expect(value).to.equal('abcdefgh');
     });
 
     it('parse set empty string', () => {
-      let [key, value] = parsers.parseSetOption('hintchars=');
+      const [key, value] = parsers.parseSetOption('hintchars=');
       expect(key).to.equal('hintchars');
       expect(value).to.equal('');
     });
diff --git a/test/console/actions/console.test.ts b/test/console/actions/console.test.ts
index e45d008..583c878 100644
--- a/test/console/actions/console.test.ts
+++ b/test/console/actions/console.test.ts
@@ -4,13 +4,13 @@ import * as consoleActions from 'console/actions/console';
 describe("console actions", () => {
   describe('hide', () => {
     it('create CONSOLE_HIDE action', () => {
-      let action = consoleActions.hide();
+      const action = consoleActions.hide();
       expect(action.type).to.equal(actions.CONSOLE_HIDE);
     });
   });
   describe("showCommand", () => {
     it('create CONSOLE_SHOW_COMMAND action', () => {
-      let action = consoleActions.showCommand('hello');
+      const action = consoleActions.showCommand('hello');
       expect(action.type).to.equal(actions.CONSOLE_SHOW_COMMAND);
       expect(action.text).to.equal('hello');
     });
@@ -18,14 +18,14 @@ describe("console actions", () => {
 
   describe("showFind", () => {
     it('create CONSOLE_SHOW_FIND action', () => {
-      let action = consoleActions.showFind();
+      const action = consoleActions.showFind();
       expect(action.type).to.equal(actions.CONSOLE_SHOW_FIND);
     });
   });
 
   describe("showError", () => {
     it('create CONSOLE_SHOW_ERROR action', () => {
-      let action = consoleActions.showError('an error');
+      const action = consoleActions.showError('an error');
       expect(action.type).to.equal(actions.CONSOLE_SHOW_ERROR);
       expect(action.text).to.equal('an error');
     });
@@ -33,7 +33,7 @@ describe("console actions", () => {
 
   describe("showInfo", () => {
     it('create CONSOLE_SHOW_INFO action', () => {
-      let action = consoleActions.showInfo('an info');
+      const action = consoleActions.showInfo('an info');
       expect(action.type).to.equal(actions.CONSOLE_SHOW_INFO);
       expect(action.text).to.equal('an info');
     });
@@ -41,14 +41,14 @@ describe("console actions", () => {
 
   describe("hideCommand", () => {
     it('create CONSOLE_HIDE_COMMAND action', () => {
-      let action = consoleActions.hideCommand();
+      const action = consoleActions.hideCommand();
       expect(action.type).to.equal(actions.CONSOLE_HIDE_COMMAND);
     });
   });
 
   describe('setConsoleText', () => {
     it('create CONSOLE_SET_CONSOLE_TEXT action', () => {
-      let action = consoleActions.setConsoleText('hello world');
+      const action = consoleActions.setConsoleText('hello world');
       expect(action.type).to.equal(actions.CONSOLE_SET_CONSOLE_TEXT);
       expect(action.consoleText).to.equal('hello world');
     });
@@ -56,14 +56,14 @@ describe("console actions", () => {
 
   describe("completionPrev", () => {
     it('create CONSOLE_COMPLETION_PREV action', () => {
-      let action = consoleActions.completionPrev();
+      const action = consoleActions.completionPrev();
       expect(action.type).to.equal(actions.CONSOLE_COMPLETION_PREV);
     });
   });
 
   describe("completionNext", () => {
     it('create CONSOLE_COMPLETION_NEXT action', () => {
-      let action = consoleActions.completionNext();
+      const action = consoleActions.completionNext();
       expect(action.type).to.equal(actions.CONSOLE_COMPLETION_NEXT);
     });
   });
diff --git a/test/console/components/console/Completion.test.tsx b/test/console/components/console/Completion.test.tsx
index 16bf11a..a271d77 100644
--- a/test/console/components/console/Completion.test.tsx
+++ b/test/console/components/console/Completion.test.tsx
@@ -3,7 +3,7 @@ import Completion from 'console/components/console/Completion'
 import ReactTestRenderer from 'react-test-renderer';
 
 describe("console/components/console/completion", () => {
-  let completions = [{
+  const completions = [{
     name: "Fruit",
     items: [{ caption: "apple" }, { caption: "banana" }, { caption: "cherry" }],
   }, {
@@ -12,14 +12,14 @@ describe("console/components/console/completion", () => {
   }];
 
   it('renders Completion component', () => {
-    let root = ReactTestRenderer.create(<Completion
+    const root = ReactTestRenderer.create(<Completion
       completions={completions}
       size={30}
       />).root;
 
     expect(root.children).to.have.lengthOf(1);
 
-    let children = root.children[0].children;
+    const children = root.children[0].children;
     expect(children).to.have.lengthOf(8);
     expect(children[0].props.title).to.equal('Fruit');
     expect(children[1].props.caption).to.equal('apple');
@@ -32,25 +32,25 @@ describe("console/components/console/completion", () => {
   });
 
   it('highlight current item', () => {
-    let root = ReactTestRenderer.create(<Completion
+    const root = ReactTestRenderer.create(<Completion
       completions={completions}
       size={30}
       select={3}
       />).root;
 
-    let children = root.children[0].children;
+    const children = root.children[0].children;
     expect(children[5].props.highlight).to.be.true;
   });
 
   it('does not highlight any items', () => {
-    let root = ReactTestRenderer.create(<Completion
+    const root = ReactTestRenderer.create(<Completion
       completions={completions}
       size={30}
       select={-1}
       />).root;
 
-    let children = root.children[0].children;
-    for (let li of children[0].children) {
+    const children = root.children[0].children;
+    for (const li of children[0].children) {
       expect(li.props.highlight).not.to.be.ok;
     }
   });
@@ -79,13 +79,13 @@ describe("console/components/console/completion", () => {
   })
 
   it('scrolls up to down with select', () => {
-    let component = ReactTestRenderer.create(<Completion
+    const component = ReactTestRenderer.create(<Completion
       completions={completions}
       size={3}
       select={1}
       />);
-    let instance = component.getInstance();
-    let root = component.root;
+    const instance = component.getInstance();
+    const root = component.root;
 
     let children = root.children[0].children;
     expect(children).to.have.lengthOf(3);
@@ -121,13 +121,13 @@ describe("console/components/console/completion", () => {
   });
 
   it('scrolls down to up with select', () => {
-    let component = ReactTestRenderer.create(<Completion
+    const component = ReactTestRenderer.create(<Completion
       completions={completions}
       size={3}
       select={5}
       />);
-    let root = component.root;
-    let instance = component.getInstance();
+    const root = component.root;
+    const instance = component.getInstance();
 
     let children = root.children[0].children;
     expect(children).to.have.lengthOf(3);
diff --git a/test/console/reducers/console.test.ts b/test/console/reducers/console.test.ts
index 47e7daf..038e712 100644
--- a/test/console/reducers/console.test.ts
+++ b/test/console/reducers/console.test.ts
@@ -3,7 +3,7 @@ import reducer from 'console/reducers';
 
 describe("console reducer", () => {
   it('return the initial state', () => {
-    let state = reducer(undefined, {});
+    const state = reducer(undefined, {});
     expect(state).to.have.property('mode', '');
     expect(state).to.have.property('messageText', '');
     expect(state).to.have.property('consoleText', '');
@@ -12,34 +12,34 @@ describe("console reducer", () => {
   });
 
   it('return next state for CONSOLE_HIDE', () => {
-    let action = { type: actions.CONSOLE_HIDE };
-    let state = reducer({ mode: 'error' }, action);
+    const action = { type: actions.CONSOLE_HIDE };
+    const state = reducer({ mode: 'error' }, action);
     expect(state).to.have.property('mode', '');
   })
 
   it('return next state for CONSOLE_SHOW_COMMAND', () => {
-    let action = { type: actions.CONSOLE_SHOW_COMMAND, text: 'open ' };
-    let state = reducer({}, action);
+    const action = { type: actions.CONSOLE_SHOW_COMMAND, text: 'open ' };
+    const state = reducer({}, action);
     expect(state).to.have.property('mode', 'command');
     expect(state).to.have.property('consoleText', 'open ');
   });
 
   it('return next state for CONSOLE_SHOW_INFO', () => {
-    let action = { type: actions.CONSOLE_SHOW_INFO, text: 'an info' };
-    let state = reducer({}, action);
+    const action = { type: actions.CONSOLE_SHOW_INFO, text: 'an info' };
+    const state = reducer({}, action);
     expect(state).to.have.property('mode', 'info');
     expect(state).to.have.property('messageText', 'an info');
   });
 
   it('return next state for CONSOLE_SHOW_ERROR', () => {
-    let action = { type: actions.CONSOLE_SHOW_ERROR, text: 'an error' };
-    let state = reducer({}, action);
+    const action = { type: actions.CONSOLE_SHOW_ERROR, text: 'an error' };
+    const state = reducer({}, action);
     expect(state).to.have.property('mode', 'error');
     expect(state).to.have.property('messageText', 'an error');
   });
 
   it('return next state for CONSOLE_HIDE_COMMAND', () => {
-    let action = { type: actions.CONSOLE_HIDE_COMMAND };
+    const action = { type: actions.CONSOLE_HIDE_COMMAND };
     let state = reducer({ mode: 'command' }, action);
     expect(state).to.have.property('mode', '');
 
@@ -48,11 +48,11 @@ describe("console reducer", () => {
   });
 
   it('return next state for CONSOLE_SET_CONSOLE_TEXT', () => {
-    let action = {
+    const action = {
       type: actions.CONSOLE_SET_CONSOLE_TEXT,
       consoleText: 'hello world'
     }
-    let state = reducer({}, action)
+    const state = reducer({}, action)
 
     expect(state).to.have.property('consoleText', 'hello world');
   });
@@ -62,7 +62,7 @@ describe("console reducer", () => {
       select: 0,
       completions: [],
     }
-    let action = {
+    const action = {
       type: actions.CONSOLE_SET_COMPLETIONS,
       completions: [{
         name: 'Apple',
@@ -78,7 +78,7 @@ describe("console reducer", () => {
   });
 
   it ('return next state for CONSOLE_COMPLETION_NEXT', () => {
-    let action = { type: actions.CONSOLE_COMPLETION_NEXT };
+    const action = { type: actions.CONSOLE_COMPLETION_NEXT };
     let state = {
       select: -1,
       completions: [{
@@ -104,7 +104,7 @@ describe("console reducer", () => {
   });
 
   it ('return next state for CONSOLE_COMPLETION_PREV', () => {
-    let action = { type: actions.CONSOLE_COMPLETION_PREV };
+    const action = { type: actions.CONSOLE_COMPLETION_PREV };
     let state = {
       select: -1,
       completions: [{
diff --git a/test/content/InputDriver.test.ts b/test/content/InputDriver.test.ts
index 441d107..367ec1d 100644
--- a/test/content/InputDriver.test.ts
+++ b/test/content/InputDriver.test.ts
@@ -50,7 +50,7 @@ describe('InputDriver', () => {
       return true;
     });
 
-    let events = [
+    const events = [
       new KeyboardEvent('keydown', { key: 'a' }),
       new KeyboardEvent('keydown', { key: 'b' }),
       new KeyboardEvent('keypress', { key: 'a' }),
@@ -58,7 +58,7 @@ describe('InputDriver', () => {
       new KeyboardEvent('keypress', { key: 'b' }),
       new KeyboardEvent('keyup', { key: 'b' }),
     ];
-    for (let e of events) {
+    for (const e of events) {
       target.dispatchEvent(e);
     }
 
@@ -102,8 +102,8 @@ describe('InputDriver', () => {
 
   it('ignores events from input elements', () => {
     ['input', 'textarea', 'select'].forEach((name) => {
-      let input = window.document.createElement(name);
-      let driver = new InputDriver(input);
+      const input = window.document.createElement(name);
+      const driver = new InputDriver(input);
       driver.onKey((key: Key): boolean => {
         expect.fail();
         return false;
@@ -113,8 +113,8 @@ describe('InputDriver', () => {
   });
 
   it('ignores events from contenteditable elements', () => {
-    let div = window.document.createElement('div');
-    let driver = new InputDriver(div);
+    const div = window.document.createElement('div');
+    const driver = new InputDriver(div);
     driver.onKey((_key: Key): boolean => {
       expect.fail();
       return false;
@@ -130,7 +130,7 @@ describe('InputDriver', () => {
 
 describe("#keyFromKeyboardEvent", () => {
   it('returns from keyboard input Ctrl+X', () => {
-    let k = keyFromKeyboardEvent(new KeyboardEvent('keydown', {
+    const k = keyFromKeyboardEvent(new KeyboardEvent('keydown', {
       key: 'x', shiftKey: false, ctrlKey: true, altKey: false, metaKey: true,
     }));
     expect(k.key).to.equal('x');
@@ -141,7 +141,7 @@ describe("#keyFromKeyboardEvent", () => {
   });
 
   it('returns from keyboard input Shift+Esc', () => {
-    let k = keyFromKeyboardEvent(new KeyboardEvent('keydown', {
+    const k = keyFromKeyboardEvent(new KeyboardEvent('keydown', {
       key: 'Escape', shiftKey: true, ctrlKey: false, altKey: false, metaKey: true
     }));
     expect(k.key).to.equal('Esc');
@@ -153,7 +153,7 @@ describe("#keyFromKeyboardEvent", () => {
 
   it('returns from keyboard input Ctrl+$', () => {
     // $ required shift pressing on most keyboards
-    let k = keyFromKeyboardEvent(new KeyboardEvent('keydown', {
+    const k = keyFromKeyboardEvent(new KeyboardEvent('keydown', {
       key: '$', shiftKey: true, ctrlKey: true, altKey: false, metaKey: false
     }));
     expect(k.key).to.equal('$');
@@ -164,7 +164,7 @@ describe("#keyFromKeyboardEvent", () => {
   });
 
   it('returns from keyboard input Crtl+Space', () => {
-    let k = keyFromKeyboardEvent(new KeyboardEvent('keydown', {
+    const k = keyFromKeyboardEvent(new KeyboardEvent('keydown', {
       key: ' ', shiftKey: false, ctrlKey: true, altKey: false, metaKey: false
     }));
     expect(k.key).to.equal('Space');
diff --git a/test/content/domains/KeySequence.test.ts b/test/content/domains/KeySequence.test.ts
index bc16189..5df5217 100644
--- a/test/content/domains/KeySequence.test.ts
+++ b/test/content/domains/KeySequence.test.ts
@@ -5,7 +5,7 @@ import Key from "../../../src/shared/settings/Key";
 describe("KeySequence", () => {
   describe('#push', () => {
     it('append a key to the sequence', () => {
-      let seq = new KeySequence([]);
+      const seq = new KeySequence([]);
       seq.push(Key.fromMapKey('g'));
       seq.push(Key.fromMapKey('<S-U>'));
 
@@ -17,7 +17,7 @@ describe("KeySequence", () => {
 
   describe('#startsWith', () => {
     it('returns true if the key sequence starts with param', () => {
-      let seq = new KeySequence([
+      const seq = new KeySequence([
         Key.fromMapKey('g'),
         Key.fromMapKey('<S-U>'),
       ]);
@@ -39,7 +39,7 @@ describe("KeySequence", () => {
     });
 
     it('returns true if the empty sequence starts with an empty sequence', () => {
-      let seq = new KeySequence([]);
+      const seq = new KeySequence([]);
 
       expect(seq.startsWith(new KeySequence([]))).to.be.true;
       expect(seq.startsWith(new KeySequence([
@@ -102,7 +102,7 @@ describe("KeySequence", () => {
 
   describe('#trimNumericPrefix', () => {
     it('removes numeric prefix', () => {
-      let seq = new KeySequence([
+      const seq = new KeySequence([
         new Key({ key: '1' }), new Key({ key: '0' }) ,
         new Key({ key: 'g' }), new Key({ key: 'g' }) , new Key({ key: '3' })  ,
       ]).trimNumericPrefix();
@@ -110,14 +110,14 @@ describe("KeySequence", () => {
     });
 
     it('returns empty if keys contains only digis', () => {
-      let seq = new KeySequence([
+      const seq = new KeySequence([
         new Key({ key: '1' }), new Key({ key: '0' })  ,
       ]).trimNumericPrefix();
       expect(seq.trimNumericPrefix().keys).to.be.empty;
     });
 
     it('returns itself if no numeric prefix', () => {
-      let seq = new KeySequence([
+      const seq = new KeySequence([
         new Key({ key: 'g' }), new Key({ key: 'g' }) , new Key({ key: '3' })  ,
       ]).trimNumericPrefix();
 
@@ -144,14 +144,14 @@ describe("KeySequence", () => {
 
   describe('#fromMapKeys', () => {
     it('returns mapped keys for Shift+Esc', () => {
-      let keys = KeySequence.fromMapKeys('<S-Esc>').keys;
+      const keys = KeySequence.fromMapKeys('<S-Esc>').keys;
       expect(keys).to.have.lengthOf(1);
       expect(keys[0].key).to.equal('Esc');
       expect(keys[0].shift).to.be.true;
     });
 
     it('returns mapped keys for a<C-B><A-C>d<M-e>', () => {
-      let keys = KeySequence.fromMapKeys('a<C-B><A-C>d<M-e>').keys;
+      const keys = KeySequence.fromMapKeys('a<C-B><A-C>d<M-e>').keys;
       expect(keys).to.have.lengthOf(5);
       expect(keys[0].key).to.equal('a');
       expect(keys[1].ctrl).to.be.true;
diff --git a/test/content/presenters/Hint.test.ts b/test/content/presenters/Hint.test.ts
index 7994788..708ddaa 100644
--- a/test/content/presenters/Hint.test.ts
+++ b/test/content/presenters/Hint.test.ts
@@ -11,43 +11,43 @@ describe('Hint', () => {
 
   describe('#constructor', () => {
     it('creates a hint element with tag name', () => {
-      let link = document.getElementById('test-link');
-      let hint = new Hint(link, 'abc');
+      const link = document.getElementById('test-link');
+      const hint = new Hint(link, 'abc');
 
-      let elem = document.querySelector('.vimvixen-hint');
+      const elem = document.querySelector('.vimvixen-hint');
       expect(elem.textContent.trim()).to.be.equal('abc');
     });
   });
 
   describe('#show', () => {
     it('shows an element', () => {
-      let link = document.getElementById('test-link');
-      let hint = new Hint(link, 'abc');
+      const link = document.getElementById('test-link');
+      const hint = new Hint(link, 'abc');
       hint.hide();
       hint.show();
 
-      let elem = document.querySelector('.vimvixen-hint') as HTMLElement;
+      const elem = document.querySelector('.vimvixen-hint') as HTMLElement;
       expect(elem.style.display).to.not.equal('none');
     });
   });
 
   describe('#hide', () => {
     it('hides an element', () => {
-      let link = document.getElementById('test-link') as HTMLElement;
-      let hint = new Hint(link, 'abc');
+      const link = document.getElementById('test-link') as HTMLElement;
+      const hint = new Hint(link, 'abc');
       hint.hide();
 
-      let elem = document.querySelector('.vimvixen-hint') as HTMLElement;
+      const elem = document.querySelector('.vimvixen-hint') as HTMLElement;
       expect(elem.style.display).to.equal('none');
     });
   });
 
   describe('#remove', () => {
     it('removes an element', () => {
-      let link = document.getElementById('test-link');
-      let hint = new Hint(link, 'abc');
+      const link = document.getElementById('test-link');
+      const hint = new Hint(link, 'abc');
 
-      let elem = document.querySelector('.vimvixen-hint');
+      const elem = document.querySelector('.vimvixen-hint');
       expect(elem.parentElement).to.not.be.null;
       hint.remove();
       expect(elem.parentElement).to.be.null;
@@ -66,8 +66,8 @@ describe('LinkHint', () => {
 
   describe('#getLink()', () => {
     it('returns value of "href" attribute', () => {
-      let link = document.getElementById('test-link1') as HTMLAnchorElement;
-      let hint = new LinkHint(link, 'abc');
+      const link = document.getElementById('test-link1') as HTMLAnchorElement;
+      const hint = new LinkHint(link, 'abc');
 
       expect(hint.getLink()).to.equal('https://google.com/');
     });
@@ -89,8 +89,8 @@ describe('LinkHint', () => {
 
   describe('#click()', () => {
     it('clicks a element', (done) => {
-      let link = document.getElementById('test-link3') as HTMLAnchorElement;
-      let hint = new LinkHint(link, 'abc');
+      const link = document.getElementById('test-link3') as HTMLAnchorElement;
+      const hint = new LinkHint(link, 'abc');
       link.onclick = () => { done() };
 
       hint.click();
@@ -106,8 +106,8 @@ describe('InputHint', () => {
       });
 
       it('focuses to the input', () => {
-        let input = document.getElementById('test-input') as HTMLInputElement;
-        let hint = new InputHint(input, 'abc');
+        const input = document.getElementById('test-input') as HTMLInputElement;
+        const hint = new InputHint(input, 'abc');
         hint.activate();
 
         expect(document.activeElement).to.equal(input);
@@ -120,8 +120,8 @@ describe('InputHint', () => {
       });
 
       it('checks and focuses to the input', () => {
-        let input = document.getElementById('test-input') as HTMLInputElement;
-        let hint = new InputHint(input, 'abc');
+        const input = document.getElementById('test-input') as HTMLInputElement;
+        const hint = new InputHint(input, 'abc');
         hint.activate();
 
         expect(input.checked).to.be.true;
@@ -133,8 +133,8 @@ describe('InputHint', () => {
       });
 
       it('focuses to the textarea', () => {
-        let textarea = document.getElementById('test-textarea') as HTMLTextAreaElement;
-        let hint = new InputHint(textarea, 'abc');
+        const textarea = document.getElementById('test-textarea') as HTMLTextAreaElement;
+        const hint = new InputHint(textarea, 'abc');
         hint.activate();
 
         expect(document.activeElement).to.equal(textarea);
@@ -147,10 +147,10 @@ describe('InputHint', () => {
       });
 
       it('clicks the button', (done) => {
-        let button = document.getElementById('test-button') as HTMLButtonElement;
+        const button = document.getElementById('test-button') as HTMLButtonElement;
         button.onclick = () => { done() };
 
-        let hint = new InputHint(button, 'abc');
+        const hint = new InputHint(button, 'abc');
         hint.activate();
       });
     });
diff --git a/test/content/repositories/AddonEnabledRepository.test.ts b/test/content/repositories/AddonEnabledRepository.test.ts
index 3cea897..7edd50e 100644
--- a/test/content/repositories/AddonEnabledRepository.test.ts
+++ b/test/content/repositories/AddonEnabledRepository.test.ts
@@ -3,7 +3,7 @@ import { expect } from 'chai';
 
 describe('AddonEnabledRepositoryImpl', () => {
   it('updates and gets current value', () => {
-    let sut = new AddonEnabledRepositoryImpl();
+    const sut = new AddonEnabledRepositoryImpl();
 
     sut.set(true);
     expect(sut.get()).to.be.true;
diff --git a/test/content/repositories/FindRepository.test.ts b/test/content/repositories/FindRepository.test.ts
index dcb2dff..0e50b0a 100644
--- a/test/content/repositories/FindRepository.test.ts
+++ b/test/content/repositories/FindRepository.test.ts
@@ -3,7 +3,7 @@ import { expect } from 'chai';
 
 describe('FindRepositoryImpl', () => {
   it('updates and gets last keyword', () => {
-    let sut = new FindRepositoryImpl();
+    const sut = new FindRepositoryImpl();
 
     expect(sut.getLastKeyword()).to.be.null;
 
diff --git a/test/content/repositories/FollowMasterRepository.test.ts b/test/content/repositories/FollowMasterRepository.test.ts
index 8c3f34e..3eb172f 100644
--- a/test/content/repositories/FollowMasterRepository.test.ts
+++ b/test/content/repositories/FollowMasterRepository.test.ts
@@ -25,7 +25,7 @@ describe('FollowMasterRepositoryImpl', () => {
 
   describe('#getTagsByPrefix', () => {
     it('gets tags matched by prefix', () => {
-      for (let tag of ['a', 'aa', 'ab', 'b', 'ba', 'bb']) {
+      for (const tag of ['a', 'aa', 'ab', 'b', 'ba', 'bb']) {
         sut.addTag(tag);
       }
       expect(sut.getTagsByPrefix('a')).to.deep.equal(['a', 'aa', 'ab']);
diff --git a/test/content/repositories/MarkRepository.test.ts b/test/content/repositories/MarkRepository.test.ts
index 7fced5f..6ddd38d 100644
--- a/test/content/repositories/MarkRepository.test.ts
+++ b/test/content/repositories/MarkRepository.test.ts
@@ -3,7 +3,7 @@ import { expect } from 'chai';
 
 describe('MarkRepositoryImpl', () => {
   it('save and load marks', () => {
-    let sut = new MarkRepositoryImpl();
+    const sut = new MarkRepositoryImpl();
 
     sut.set('a', { x: 10, y: 20 });
     expect(sut.get('a')).to.deep.equal({ x: 10, y: 20 });
diff --git a/test/content/repositories/SettingRepository.test.ts b/test/content/repositories/SettingRepository.test.ts
index db4c528..e45d7c4 100644
--- a/test/content/repositories/SettingRepository.test.ts
+++ b/test/content/repositories/SettingRepository.test.ts
@@ -4,9 +4,9 @@ import Settings from '../../../src/shared/settings/Settings';
 
 describe('SettingRepositoryImpl', () => {
   it('updates and gets current value', () => {
-    let sut = new SettingRepositoryImpl();
+    const sut = new SettingRepositoryImpl();
 
-    let settings = Settings.fromJSON({
+    const settings = Settings.fromJSON({
       keymaps: {},
       search:{
         default: 'google',
@@ -24,7 +24,7 @@ describe('SettingRepositoryImpl', () => {
 
     sut.set(settings);
 
-    let actual = sut.get();
+    const actual = sut.get();
     expect(actual.properties.hintchars).to.equal('abcd1234');
   });
 });
diff --git a/test/content/usecases/ClipboardUseCase.test.ts b/test/content/usecases/ClipboardUseCase.test.ts
index a863651..2e711c6 100644
--- a/test/content/usecases/ClipboardUseCase.test.ts
+++ b/test/content/usecases/ClipboardUseCase.test.ts
@@ -14,7 +14,7 @@ describe('ClipboardUseCase', () => {
   let sut: ClipboardUseCase;
 
   beforeEach(() => {
-    var modal = <ConsoleClient>{};
+    const modal = <ConsoleClient>{};
 
     clipboardRepository = <ClipboardRepository>{ read() {}, write(_) {} };
     operationClient = <OperationClient>{ internalOpenUrl(_) {} };
@@ -29,13 +29,13 @@ describe('ClipboardUseCase', () => {
 
   describe('#yankCurrentURL', () => {
     it('yanks current url', async () => {
-      let href = window.location.href;
-      var mockRepository = sinon.mock(clipboardRepository);
+      const href = window.location.href;
+      const mockRepository = sinon.mock(clipboardRepository);
       mockRepository.expects('write').withArgs(href);
-      var mockConsoleClient = sinon.mock(consoleClient);
+      const mockConsoleClient = sinon.mock(consoleClient);
       mockConsoleClient.expects('info').withArgs('Yanked ' + href);
 
-      let yanked = await sut.yankCurrentURL();
+      const yanked = await sut.yankCurrentURL();
 
       expect(yanked).to.equal(href);
       mockRepository.verify();
@@ -45,9 +45,9 @@ describe('ClipboardUseCase', () => {
 
   describe('#openOrSearch', () => {
     it('opens url from the clipboard', async () => {
-      let url = 'https://github.com/ueokande/vim-vixen'
+      const url = 'https://github.com/ueokande/vim-vixen'
       sinon.stub(clipboardRepository, 'read').returns(url);
-      let mockOperationClient = sinon.mock(operationClient);
+      const mockOperationClient = sinon.mock(operationClient);
       mockOperationClient.expects('internalOpenUrl').withArgs(url, true);
 
       await sut.openOrSearch(true);
@@ -56,9 +56,9 @@ describe('ClipboardUseCase', () => {
     });
 
     it('opens search results from the clipboard', async () => {
-      let url = 'https://google.com/search?q=banana';
+      const url = 'https://google.com/search?q=banana';
       sinon.stub(clipboardRepository, 'read').returns('banana');
-      let mockOperationClient = sinon.mock(operationClient);
+      const mockOperationClient = sinon.mock(operationClient);
       mockOperationClient.expects('internalOpenUrl').withArgs(url, true);
 
       await sut.openOrSearch(true);
diff --git a/test/content/usecases/FindUseCase.test.ts b/test/content/usecases/FindUseCase.test.ts
index ddd4cd4..3978dbc 100644
--- a/test/content/usecases/FindUseCase.test.ts
+++ b/test/content/usecases/FindUseCase.test.ts
@@ -32,7 +32,7 @@ class MockFindPresenter implements FindPresenter {
   }
 
   find(keyword: string, _backward: boolean): boolean {
-    let found = this.document.includes(keyword);
+    const found = this.document.includes(keyword);
     this.highlighted = found;
     return found;
   }
diff --git a/test/content/usecases/HintKeyProducer.test.ts b/test/content/usecases/HintKeyProducer.test.ts
index feafffb..5841ae9 100644
--- a/test/content/usecases/HintKeyProducer.test.ts
+++ b/test/content/usecases/HintKeyProducer.test.ts
@@ -10,13 +10,13 @@ describe('HintKeyProducer class', () => {
 
   describe('#produce', () => {
     it('produce incremented keys', () => {
-      let charset = 'abc';
-      let sequences = [
+      const charset = 'abc';
+      const sequences = [
         'a', 'b', 'c',
         'aa', 'ab', 'ac', 'ba', 'bb', 'bc', 'ca', 'cb', 'cc',
         'aaa', 'aab', 'aac', 'aba']
 
-      let producer = new HintKeyProducer(charset);
+      const producer = new HintKeyProducer(charset);
       for (let i = 0; i < sequences.length; ++i) {
         expect(producer.produce()).to.equal(sequences[i]);
       }
diff --git a/test/content/usecases/KeymapUseCase.test.ts b/test/content/usecases/KeymapUseCase.test.ts
index 598d5a3..032d4fc 100644
--- a/test/content/usecases/KeymapUseCase.test.ts
+++ b/test/content/usecases/KeymapUseCase.test.ts
@@ -52,7 +52,7 @@ class MockAddressRepository implements AddressRepository {
 
 describe('KeymapUseCase', () => {
   context('with no-digis keymaps', () => {
-    let settings = Settings.fromJSON({
+    const settings = Settings.fromJSON({
       keymaps: {
         k: {type: 'scroll.vertically', count: -1},
         j: {type: 'scroll.vertically', count: 1},
@@ -88,7 +88,7 @@ describe('KeymapUseCase', () => {
   });
 
   context('when keymaps containing numeric mappings', () => {
-    let settings = Settings.fromJSON({
+    const settings = Settings.fromJSON({
       keymaps: {
         20: {type: "scroll.top"},
         g5: {type: 'scroll.bottom'},
@@ -132,7 +132,7 @@ describe('KeymapUseCase', () => {
   });
 
   context('when the keys are mismatched with the operations', () => {
-    let settings = Settings.fromJSON({
+    const settings = Settings.fromJSON({
       keymaps: {
         gg: {type: "scroll.top"},
         G: {type: "scroll.bottom"},
@@ -170,7 +170,7 @@ describe('KeymapUseCase', () => {
   });
 
   context('when the site matches to the blacklist', () => {
-    let settings = Settings.fromJSON({
+    const settings = Settings.fromJSON({
       keymaps: {
         k: {type: 'scroll.vertically', count: -1},
         a: {type: 'addon.enable'},
@@ -197,7 +197,7 @@ describe('KeymapUseCase', () => {
   });
 
   context('when the site matches to the partial blacklist', () => {
-    let settings = Settings.fromJSON({
+    const settings = Settings.fromJSON({
       keymaps: {
         k: {type: 'scroll.vertically', count: -1},
         j: {type: 'scroll.vertically', count: 1},
diff --git a/test/content/usecases/SettingUseCaase.test.ts b/test/content/usecases/SettingUseCaase.test.ts
index 136c5af..cf14e6e 100644
--- a/test/content/usecases/SettingUseCaase.test.ts
+++ b/test/content/usecases/SettingUseCaase.test.ts
@@ -38,7 +38,7 @@ describe('AddonEnabledUseCase', () => {
   let sut: SettingUseCase;
 
   beforeEach(() => {
-    let testSettings = {
+    const testSettings = {
       keymaps: {},
       search: {
         default: 'google',
@@ -61,10 +61,10 @@ describe('AddonEnabledUseCase', () => {
 
   describe('#reload', () => {
     it('loads settings and store to repository', async() => {
-      let settings = await sut.reload();
+      const settings = await sut.reload();
       expect(settings.properties.hintchars).to.equal('abcd1234');
 
-      let saved = repository.get();
+      const saved = repository.get();
       expect(saved.properties.hintchars).to.equal('abcd1234');
     });
   });
diff --git a/test/settings/components/form/BlacklistForm.test.tsx b/test/settings/components/form/BlacklistForm.test.tsx
index 7daf513..6c329ff 100644
--- a/test/settings/components/form/BlacklistForm.test.tsx
+++ b/test/settings/components/form/BlacklistForm.test.tsx
@@ -10,11 +10,11 @@ import Blacklist from '../../../../src/shared/settings/Blacklist';
 describe("settings/form/BlacklistForm", () => {
   describe('render', () => {
     it('renders BlacklistForm', () => {
-      let root = ReactTestRenderer.create(
+      const root = ReactTestRenderer.create(
         <BlacklistForm value={Blacklist.fromJSON(['*.slack.com', 'www.google.com/maps'])} />,
       ).root;
 
-      let children = root.children[0].children;
+      const children = root.children[0].children;
       expect(children).to.have.lengthOf(3);
       expect(children[0].children[0].props.value).to.equal('*.slack.com');
       expect(children[1].children[0].props.value).to.equal('www.google.com/maps');
@@ -22,9 +22,9 @@ describe("settings/form/BlacklistForm", () => {
     });
 
     it('renders blank value', () => {
-      let root = ReactTestRenderer.create(<BlacklistForm />).root;
+      const root = ReactTestRenderer.create(<BlacklistForm />).root;
 
-      let children = root.children[0].children;
+      const children = root.children[0].children;
       expect(children).to.have.lengthOf(1);
       expect(children[0].props.name).to.equal('add');
     });
@@ -48,14 +48,14 @@ describe("settings/form/BlacklistForm", () => {
         ReactDOM.render(<BlacklistForm
           value={Blacklist.fromJSON(['*.slack.com', 'www.google.com/maps*'])}
           onChange={value => {
-            let urls = value.items.map(item => item.pattern);
+            const urls = value.items.map(item => item.pattern);
             expect(urls).to.have.members(['gitter.im', 'www.google.com/maps*']);
             done();
           }}
         />, container)
       });
 
-      let input = document.querySelectorAll('input[type=text]')[0];
+      const input = document.querySelectorAll('input[type=text]')[0];
       input.value = 'gitter.im';
       ReactTestUtils.Simulate.change(input);
     });
@@ -65,14 +65,14 @@ describe("settings/form/BlacklistForm", () => {
         ReactDOM.render(<BlacklistForm
           value={Blacklist.fromJSON(['*.slack.com', 'www.google.com/maps*'])}
           onChange={value => {
-            let urls = value.items.map(item => item.pattern);
+            const urls = value.items.map(item => item.pattern);
             expect(urls).to.have.members(['www.google.com/maps*']);
             done();
           }}
         />, container)
       });
 
-      let button = document.querySelectorAll('input[type=button]')[0];
+      const button = document.querySelectorAll('input[type=button]')[0];
       ReactTestUtils.Simulate.click(button);
     });
 
@@ -81,14 +81,14 @@ describe("settings/form/BlacklistForm", () => {
         ReactDOM.render(<BlacklistForm
           value={Blacklist.fromJSON(['*.slack.com'])}
           onChange={value => {
-            let urls = value.items.map(item => item.pattern);
+            const urls = value.items.map(item => item.pattern);
             expect(urls).to.have.members(['*.slack.com', '']);
             done();
           }}
         />, container);
       });
 
-      let button = document.querySelector('input[type=button].ui-add-button');
+      const button = document.querySelector('input[type=button].ui-add-button');
       ReactTestUtils.Simulate.click(button);
     });
   });
diff --git a/test/settings/components/form/KeymapsForm.test.tsx b/test/settings/components/form/KeymapsForm.test.tsx
index 1d1e77c..ccc772c 100644
--- a/test/settings/components/form/KeymapsForm.test.tsx
+++ b/test/settings/components/form/KeymapsForm.test.tsx
@@ -9,23 +9,23 @@ import { expect } from 'chai';
 describe("settings/form/KeymapsForm", () => {
   describe('render', () => {
     it('renders keymap fields', () => {
-      let root = ReactTestRenderer.create(<KeymapsForm value={FormKeymaps.fromJSON({
+      const root = ReactTestRenderer.create(<KeymapsForm value={FormKeymaps.fromJSON({
         'scroll.vertically?{"count":1}': 'j',
         'scroll.vertically?{"count":-1}': 'k',
       })} />).root
 
-      let inputj = root.findByProps({ id: 'scroll.vertically?{"count":1}' });
-      let inputk = root.findByProps({ id: 'scroll.vertically?{"count":-1}' });
+      const inputj = root.findByProps({ id: 'scroll.vertically?{"count":1}' });
+      const inputk = root.findByProps({ id: 'scroll.vertically?{"count":-1}' });
 
       expect(inputj.props.value).to.equal('j');
       expect(inputk.props.value).to.equal('k');
     });
 
     it('renders blank value', () => {
-      let root = ReactTestRenderer.create(<KeymapsForm />).root;
+      const root = ReactTestRenderer.create(<KeymapsForm />).root;
 
-      let inputj = root.findByProps({ id: 'scroll.vertically?{"count":1}' });
-      let inputk = root.findByProps({ id: 'scroll.vertically?{"count":-1}' });
+      const inputj = root.findByProps({ id: 'scroll.vertically?{"count":1}' });
+      const inputk = root.findByProps({ id: 'scroll.vertically?{"count":-1}' });
 
       expect(inputj.props.value).to.be.empty;
       expect(inputk.props.value).to.be.empty;
@@ -58,7 +58,7 @@ describe("settings/form/KeymapsForm", () => {
           }} />, container);
       });
 
-      let input = document.getElementById('scroll.vertically?{"count":1}');
+      const input = document.getElementById('scroll.vertically?{"count":1}');
       input.value = 'jjj';
       ReactTestUtils.Simulate.change(input);
     });
diff --git a/test/settings/components/form/PropertiesForm.test.tsx b/test/settings/components/form/PropertiesForm.test.tsx
index 0e33cc8..4a0e25a 100644
--- a/test/settings/components/form/PropertiesForm.test.tsx
+++ b/test/settings/components/form/PropertiesForm.test.tsx
@@ -7,19 +7,19 @@ import PropertiesForm from 'settings/components/form/PropertiesForm'
 describe("settings/form/PropertiesForm", () => {
   describe('render', () => {
     it('renders PropertiesForm', () => {
-      let types = {
+      const types = {
         mystr: 'string',
         mynum: 'number',
         mybool: 'boolean',
         empty: 'string',
       }
-      let values = {
+      const values = {
         mystr: 'abc',
         mynum: 123,
         mybool: true,
       };
 
-      let root = ReactTestRenderer.create(
+      const root = ReactTestRenderer.create(
         <PropertiesForm types={types} value={values} />,
       ).root
 
@@ -62,7 +62,7 @@ describe("settings/form/PropertiesForm", () => {
         />, container);
       });
 
-      let input = document.querySelector('input[name=myvalue]');
+      const input = document.querySelector('input[name=myvalue]');
       input.value = 'abcd'
       ReactTestUtils.Simulate.change(input);
     });
@@ -79,7 +79,7 @@ describe("settings/form/PropertiesForm", () => {
         />, container);
       });
 
-      let input = document.querySelector('input[name=myvalue]');
+      const input = document.querySelector('input[name=myvalue]');
       input.value = '1234'
       ReactTestUtils.Simulate.change(input);
     });
@@ -96,7 +96,7 @@ describe("settings/form/PropertiesForm", () => {
         />, container);
       });
 
-      let input = document.querySelector('input[name=myvalue]');
+      const input = document.querySelector('input[name=myvalue]');
       input.checked = true;
       ReactTestUtils.Simulate.change(input);
     });
diff --git a/test/settings/components/form/SearchEngineForm.test.tsx b/test/settings/components/form/SearchEngineForm.test.tsx
index 1f0420d..b918203 100644
--- a/test/settings/components/form/SearchEngineForm.test.tsx
+++ b/test/settings/components/form/SearchEngineForm.test.tsx
@@ -8,17 +8,17 @@ import { FormSearch } from 'shared/SettingData';
 describe("settings/form/SearchForm", () => {
   describe('render', () => {
     it('renders SearchForm', () => {
-      let root = ReactTestRenderer.create(<SearchForm value={FormSearch.fromJSON({
+      const root = ReactTestRenderer.create(<SearchForm value={FormSearch.fromJSON({
         default: 'google',
         engines: [['google', 'google.com'], ['yahoo', 'yahoo.com']],
       })} />).root;
 
-      let names = root.findAllByProps({ name: 'name' });
+      const names = root.findAllByProps({ name: 'name' });
       expect(names).to.have.lengthOf(2);
       expect(names[0].props.value).to.equal('google');
       expect(names[1].props.value).to.equal('yahoo');
 
-      let urls = root.findAllByProps({ name: 'url' });
+      const urls = root.findAllByProps({ name: 'url' });
       expect(urls).to.have.lengthOf(2);
       expect(urls[0].props.value).to.equal('google.com');
       expect(urls[1].props.value).to.equal('yahoo.com');
@@ -46,7 +46,7 @@ describe("settings/form/SearchForm", () => {
               engines: [['google', 'google.com'], ['yahoo', 'yahoo.com']]
           })}
           onChange={value => {
-            let json = value.toJSON();
+            const json = value.toJSON();
             expect(json.default).to.equal('louvre');
             expect(json.engines).to.have.lengthOf(2)
             expect(json.engines).to.have.deep.members(
@@ -56,10 +56,10 @@ describe("settings/form/SearchForm", () => {
           }} />, container);
       });
 
-      let radio = document.querySelectorAll('input[type=radio]');
+      const radio = document.querySelectorAll('input[type=radio]');
       radio.checked = true;
 
-      let name = document.querySelector('input[name=name]');
+      const name = document.querySelector('input[name=name]');
       name.value = 'louvre';
 
       ReactTestUtils.Simulate.change(name);
@@ -72,7 +72,7 @@ describe("settings/form/SearchForm", () => {
             engines: [['louvre', 'google.com'], ['yahoo', 'yahoo.com']]
           })}
           onChange={value => {
-            let json = value.toJSON();
+            const json = value.toJSON();
             expect(json.default).to.equal('yahoo');
             expect(json.engines).to.have.lengthOf(1)
             expect(json.engines).to.have.deep.members(
@@ -82,7 +82,7 @@ describe("settings/form/SearchForm", () => {
           }} />, container);
       });
 
-      let button = document.querySelector('input[type=button]');
+      const button = document.querySelector('input[type=button]');
       ReactTestUtils.Simulate.click(button);
     });
 
@@ -93,7 +93,7 @@ describe("settings/form/SearchForm", () => {
             engines: [['google', 'google.com']]
           })}
           onChange={value => {
-            let json = value.toJSON();
+            const json = value.toJSON();
             expect(json.default).to.equal('yahoo');
             expect(json.engines).to.have.lengthOf(2)
             expect(json.engines).to.have.deep.members(
@@ -103,7 +103,7 @@ describe("settings/form/SearchForm", () => {
           }} />, container);
       });
 
-      let button = document.querySelector('input[type=button].ui-add-button');
+      const button = document.querySelector('input[type=button].ui-add-button');
       ReactTestUtils.Simulate.click(button);
     });
   });
diff --git a/test/settings/components/ui/input.test.tsx b/test/settings/components/ui/input.test.tsx
index 432efcb..a3e7ff4 100644
--- a/test/settings/components/ui/input.test.tsx
+++ b/test/settings/components/ui/input.test.tsx
@@ -24,8 +24,8 @@ describe("settings/ui/Input", () => {
           container);
       });
 
-      let label = document.querySelector('label');
-      let input = document.querySelector('input');
+      const label = document.querySelector('label');
+      const input = document.querySelector('input');
       expect(label.textContent).to.contain('myfield');
       expect(input.type).to.contain('text');
       expect(input.name).to.contain('myname');
@@ -40,7 +40,7 @@ describe("settings/ui/Input", () => {
         }}/>, container);
       });
 
-      let input = document.querySelector('input');
+      const input = document.querySelector('input');
       input.value = 'newvalue';
       ReactTestUtils.Simulate.change(input);
     });
@@ -54,8 +54,8 @@ describe("settings/ui/Input", () => {
           container);
       });
 
-      let label = document.querySelector('label');
-      let input = document.querySelector('input');
+      const label = document.querySelector('label');
+      const input = document.querySelector('input');
       expect(label.textContent).to.contain('myfield');
       expect(input.type).to.contain('radio');
       expect(input.name).to.contain('myname');
@@ -71,7 +71,7 @@ describe("settings/ui/Input", () => {
         container);
       });
 
-      let input = document.querySelector('input');
+      const input = document.querySelector('input');
       input.checked = true;
       ReactTestUtils.Simulate.change(input);
     });
@@ -85,9 +85,9 @@ describe("settings/ui/Input", () => {
           container);
       });
 
-      let label = document.querySelector('label');
-      let textarea = document.querySelector('textarea');
-      let error = document.querySelector('.settings-ui-input-error');
+      const label = document.querySelector('label');
+      const textarea = document.querySelector('textarea');
+      const error = document.querySelector('.settings-ui-input-error');
       expect(label.textContent).to.contain('myfield');
       expect(textarea.nodeName).to.contain('TEXTAREA');
       expect(textarea.name).to.contain('myname');
@@ -103,7 +103,7 @@ describe("settings/ui/Input", () => {
         }}/>, container);
       });
 
-      let input = document.querySelector('textarea');
+      const input = document.querySelector('textarea');
       input.value = 'newvalue'
       ReactTestUtils.Simulate.change(input);
     });
diff --git a/test/settings/reducers/setting.test.ts b/test/settings/reducers/setting.test.ts
index 376d66e..60df061 100644
--- a/test/settings/reducers/setting.test.ts
+++ b/test/settings/reducers/setting.test.ts
@@ -3,51 +3,51 @@ import settingReducer from 'settings/reducers/setting';
 
 describe("settings setting reducer", () => {
   it('return the initial state', () => {
-    let state = settingReducer(undefined, {});
+    const state = settingReducer(undefined, {});
     expect(state).to.have.deep.property('source', 'json');
     expect(state).to.have.deep.property('error', '');
   });
 
   it('return next state for SETTING_SET_SETTINGS', () => {
-    let action = {
+    const action = {
       type: actions.SETTING_SET_SETTINGS,
       source: 'json',
       json: '{ "key": "value" }',
       form: {},
     };
-    let state = settingReducer(undefined, action);
+    const state = settingReducer(undefined, action);
     expect(state).to.have.deep.property('source', 'json');
     expect(state).to.have.deep.property('json', '{ "key": "value" }');
     expect(state).to.have.deep.property('form', {});
   });
 
   it('return next state for SETTING_SHOW_ERROR', () => {
-    let action = {
+    const action = {
       type: actions.SETTING_SHOW_ERROR,
       error: 'bad value',
       json: '{}',
     };
-    let state = settingReducer(undefined, action);
+    const state = settingReducer(undefined, action);
     expect(state).to.have.deep.property('error', 'bad value');
     expect(state).to.have.deep.property('json', '{}');
   });
 
   it('return next state for SETTING_SWITCH_TO_FORM', () => {
-    let action = {
+    const action = {
       type: actions.SETTING_SWITCH_TO_FORM,
       form: {},
     };
-    let state = settingReducer(undefined, action);
+    const state = settingReducer(undefined, action);
     expect(state).to.have.deep.property('form', {});
     expect(state).to.have.deep.property('source', 'form');
   });
 
   it('return next state for SETTING_SWITCH_TO_JSON', () => {
-    let action = {
+    const action = {
       type: actions.SETTING_SWITCH_TO_JSON,
       json: '{}',
     };
-    let state = settingReducer(undefined, action);
+    const state = settingReducer(undefined, action);
     expect(state).to.have.deep.property('json', '{}');
     expect(state).to.have.deep.property('source', 'json');
   });
diff --git a/test/shared/SettingData.test.ts b/test/shared/SettingData.test.ts
index 5de7770..0632176 100644
--- a/test/shared/SettingData.test.ts
+++ b/test/shared/SettingData.test.ts
@@ -9,12 +9,12 @@ describe('shared/SettingData', () => {
   describe('FormKeymaps', () => {
     describe('#valueOF to #toKeymaps', () => {
       it('parses form keymaps and convert to operations', () => {
-        let data = {
+        const data = {
           'scroll.vertically?{"count":1}': 'j',
           'scroll.home': '0',
         };
 
-        let keymaps = FormKeymaps.fromJSON(data).toKeymaps().toJSON();
+        const keymaps = FormKeymaps.fromJSON(data).toKeymaps().toJSON();
         expect(keymaps).to.deep.equal({
           'j': { type: 'scroll.vertically', count: 1 },
           '0': { type: 'scroll.home' },
@@ -24,12 +24,12 @@ describe('shared/SettingData', () => {
 
     describe('#fromKeymaps to #toJSON', () => {
       it('create from a Keymaps and create a JSON object', () => {
-        let keymaps: Keymaps = Keymaps.fromJSON({
+        const keymaps: Keymaps = Keymaps.fromJSON({
           'j': { type: 'scroll.vertically', count: 1 },
           '0': { type: 'scroll.home' },
         });
 
-        let form = FormKeymaps.fromKeymaps(keymaps).toJSON();
+        const form = FormKeymaps.fromKeymaps(keymaps).toJSON();
         expect(form).to.deep.equal({
           'scroll.vertically?{"count":1}': 'j',
           'scroll.home': '0',
@@ -41,7 +41,7 @@ describe('shared/SettingData', () => {
   describe('JSONSettings', () => {
     describe('#valueOf to #toSettings', () => {
       it('parse object and create a Settings', () => {
-        let o = `{
+        const o = `{
           "keymaps": {},
           "search": {
             "default": "google",
@@ -57,14 +57,14 @@ describe('shared/SettingData', () => {
           "blacklist": []
         }`;
 
-        let settings = JSONTextSettings.fromText(o).toSettings();
+        const settings = JSONTextSettings.fromText(o).toSettings();
         expect(settings.toJSON()).to.deep.equal(JSON.parse(o));
       });
     });
 
     describe('#fromSettings to #toJSON', () => {
       it('create from a Settings and create a JSON string', () => {
-        let o = Settings.fromJSON({
+        const o = Settings.fromJSON({
           keymaps: {},
           search: {
             default: "google",
@@ -80,7 +80,7 @@ describe('shared/SettingData', () => {
           blacklist: [],
         });
 
-        let json = JSONTextSettings.fromSettings(o).toJSONText();
+        const json = JSONTextSettings.fromSettings(o).toJSONText();
         expect(JSON.parse(json)).to.deep.equal(o.toJSON());
       });
     });
@@ -89,7 +89,7 @@ describe('shared/SettingData', () => {
   describe('FormSettings', () => {
     describe('#valueOf to #toSettings', () => {
       it('parse object and create a Settings', () => {
-        let data = {
+        const data = {
           keymaps: {
             'scroll.vertically?{"count":1}': 'j',
             'scroll.home': '0',
@@ -108,7 +108,7 @@ describe('shared/SettingData', () => {
           blacklist: []
         };
 
-        let settings = FormSettings.fromJSON(data).toSettings();
+        const settings = FormSettings.fromJSON(data).toSettings();
         expect(settings.toJSON()).to.deep.equal({
           keymaps: {
             'j': { type: 'scroll.vertically', count: 1 },
@@ -132,7 +132,7 @@ describe('shared/SettingData', () => {
 
     describe('#fromSettings to #toJSON', () => {
       it('create from a Settings and create a JSON string', () => {
-        let data: Settings = Settings.fromJSON({
+        const data: Settings = Settings.fromJSON({
           keymaps: {
             'j': { type: 'scroll.vertically', count: 1 },
             '0': { type: 'scroll.home' },
@@ -151,7 +151,7 @@ describe('shared/SettingData', () => {
           blacklist: [],
         });
 
-        let json = FormSettings.fromSettings(data).toJSON();
+        const json = FormSettings.fromSettings(data).toJSON();
         expect(json).to.deep.equal({
           keymaps: {
             'scroll.vertically?{"count":1}': 'j',
@@ -177,7 +177,7 @@ describe('shared/SettingData', () => {
   describe('SettingData', () => {
     describe('#valueOf to #toJSON', () => {
       it('parse object from json source', () => {
-        let data = {
+        const data = {
           source: 'json',
           json: `{
             "keymaps": {},
@@ -196,13 +196,13 @@ describe('shared/SettingData', () => {
           }`,
         };
 
-        let j = SettingData.fromJSON(data).toJSON();
+        const j = SettingData.fromJSON(data).toJSON();
         expect(j.source).to.equal('json');
         expect(j.json).to.be.a('string');
       });
 
       it('parse object from form source', () => {
-        let data = {
+        const data = {
           source: 'form',
           form: {
             keymaps: {},
@@ -221,7 +221,7 @@ describe('shared/SettingData', () => {
           },
         };
 
-        let j = SettingData.fromJSON(data).toJSON();
+        const j = SettingData.fromJSON(data).toJSON();
         expect(j.source).to.equal('form');
         expect(j.form).to.deep.equal({
           keymaps: {},
@@ -243,7 +243,7 @@ describe('shared/SettingData', () => {
 
     describe('#toSettings', () => {
       it('parse object from json source', () => {
-        let data = {
+        const data = {
           source: 'json',
           json: `{
             "keymaps": {},
@@ -262,12 +262,12 @@ describe('shared/SettingData', () => {
           }`,
         };
 
-        let settings = SettingData.fromJSON(data).toSettings();
+        const settings = SettingData.fromJSON(data).toSettings();
         expect(settings.search.defaultEngine).to.equal('google');
       });
 
       it('parse object from form source', () => {
-        let data = {
+        const data = {
           source: 'form',
           form: {
             keymaps: {},
@@ -286,7 +286,7 @@ describe('shared/SettingData', () => {
           },
         };
 
-        let settings = SettingData.fromJSON(data).toSettings();
+        const settings = SettingData.fromJSON(data).toSettings();
         expect(settings.search.defaultEngine).to.equal('yahoo');
       });
     });
diff --git a/test/shared/operations.test.ts b/test/shared/operations.test.ts
index 42a3eed..fbb6193 100644
--- a/test/shared/operations.test.ts
+++ b/test/shared/operations.test.ts
@@ -3,7 +3,7 @@ import * as operations from 'shared/operations';
 describe('operations', () => {
   describe('#valueOf', () => {
     it('returns an Operation', () => {
-      let op: operations.Operation = operations.valueOf({
+      const op: operations.Operation = operations.valueOf({
         type: operations.SCROLL_VERTICALLY,
         count: 10,
       });
@@ -18,7 +18,7 @@ describe('operations', () => {
     });
 
     it('fills default valus of optional parameter', () => {
-      let op: operations.Operation = operations.valueOf({
+      const op: operations.Operation = operations.valueOf({
         type: operations.COMMAND_SHOW_OPEN,
       });
 
diff --git a/test/shared/settings/Blacklist.test.ts b/test/shared/settings/Blacklist.test.ts
index 0112757..dfd036e 100644
--- a/test/shared/settings/Blacklist.test.ts
+++ b/test/shared/settings/Blacklist.test.ts
@@ -5,13 +5,13 @@ import Key from '../../../src/shared/settings/Key';
 describe('BlacklistItem', () => {
   describe('#fromJSON', () => {
     it('parses string pattern', () => {
-      let item = BlacklistItem.fromJSON('example.com');
+      const item = BlacklistItem.fromJSON('example.com');
       expect(item.pattern).to.equal('example.com');
       expect(item.partial).to.be.false;
     });
 
     it('parses partial blacklist item', () => {
-      let item = BlacklistItem.fromJSON({ url: 'example.com', keys: ['j', 'k']});
+      const item = BlacklistItem.fromJSON({ url: 'example.com', keys: ['j', 'k']});
       expect(item.pattern).to.equal('example.com');
       expect(item.partial).to.be.true;
       expect(item.keys).to.deep.equal(['j', 'k']);
@@ -20,12 +20,12 @@ describe('BlacklistItem', () => {
 
   describe('#matches', () => {
     it('matches by "*"', () => {
-      let item = BlacklistItem.fromJSON('*');
+      const item = BlacklistItem.fromJSON('*');
       expect(item.matches(new URL('https://github.com/abc'))).to.be.true;
     });
 
     it('matches by hostname', () => {
-      let item = BlacklistItem.fromJSON('github.com');
+      const item = BlacklistItem.fromJSON('github.com');
       expect(item.matches(new URL('https://github.com'))).to.be.true;
       expect(item.matches(new URL('https://gist.github.com'))).to.be.false;
       expect(item.matches(new URL('https://github.com/ueokande'))).to.be.true;
@@ -34,14 +34,14 @@ describe('BlacklistItem', () => {
     });
 
     it('matches by hostname with wildcard', () => {
-      let item = BlacklistItem.fromJSON('*.github.com');
+      const item = BlacklistItem.fromJSON('*.github.com');
 
       expect(item.matches(new URL('https://github.com'))).to.be.false;
       expect(item.matches(new URL('https://gist.github.com'))).to.be.true;
     });
 
     it('matches by path', () => {
-      let item = BlacklistItem.fromJSON('github.com/abc');
+      const item = BlacklistItem.fromJSON('github.com/abc');
 
       expect(item.matches(new URL('https://github.com/abc'))).to.be.true;
       expect(item.matches(new URL('https://github.com/abcdef'))).to.be.false;
@@ -49,7 +49,7 @@ describe('BlacklistItem', () => {
     });
 
     it('matches by path with wildcard', () => {
-      let item = BlacklistItem.fromJSON('github.com/abc*');
+      const item = BlacklistItem.fromJSON('github.com/abc*');
 
       expect(item.matches(new URL('https://github.com/abc'))).to.be.true;
       expect(item.matches(new URL('https://github.com/abcdef'))).to.be.true;
@@ -57,14 +57,14 @@ describe('BlacklistItem', () => {
     });
 
     it('matches address and port', () => {
-      let item = BlacklistItem.fromJSON('127.0.0.1:8888');
+      const item = BlacklistItem.fromJSON('127.0.0.1:8888');
 
       expect(item.matches(new URL('http://127.0.0.1:8888/'))).to.be.true;
       expect(item.matches(new URL('http://127.0.0.1:8888/hello'))).to.be.true;
     });
 
     it('matches with partial blacklist', () => {
-      let item = BlacklistItem.fromJSON({ url: 'google.com', keys: ['j', 'k'] });
+      const item = BlacklistItem.fromJSON({ url: 'google.com', keys: ['j', 'k'] });
 
       expect(item.matches(new URL('https://google.com'))).to.be.true;
       expect(item.matches(new URL('https://yahoo.com'))).to.be.false;
@@ -73,7 +73,7 @@ describe('BlacklistItem', () => {
 
   describe('#includesPartialKeys', () => {
     it('matches with partial keys', () => {
-      let item = BlacklistItem.fromJSON({url: 'google.com', keys: ['j', 'k', '<C-U>']});
+      const item = BlacklistItem.fromJSON({url: 'google.com', keys: ['j', 'k', '<C-U>']});
 
       expect(item.includeKey(new URL('http://google.com/maps'), Key.fromMapKey('j'))).to.be.true;
       expect(item.includeKey(new URL('http://google.com/maps'), Key.fromMapKey('<C-U>'))).to.be.true;
@@ -87,14 +87,14 @@ describe('BlacklistItem', () => {
 describe('Blacklist', () => {
   describe('#fromJSON', () => {
     it('parses string list', () => {
-      let blacklist = Blacklist.fromJSON(['example.com', 'example.org']);
+      const blacklist = Blacklist.fromJSON(['example.com', 'example.org']);
       expect(blacklist.toJSON()).to.deep.equals([
         'example.com', 'example.org',
       ]);
     });
 
     it('parses mixed blacklist', () => {
-      let blacklist = Blacklist.fromJSON([
+      const blacklist = Blacklist.fromJSON([
         { url: 'example.com', keys: ['j', 'k']},
         'example.org',
       ]);
@@ -105,21 +105,21 @@ describe('Blacklist', () => {
     });
 
     it('parses empty blacklist', () => {
-      let blacklist = Blacklist.fromJSON([]);
+      const blacklist = Blacklist.fromJSON([]);
       expect(blacklist.toJSON()).to.deep.equals([]);
     });
   });
 
   describe('#includesEntireBlacklist', () => {
     it('matches a url with entire blacklist', () => {
-      let blacklist = Blacklist.fromJSON(['google.com', '*.github.com']);
+      const blacklist = Blacklist.fromJSON(['google.com', '*.github.com']);
       expect(blacklist.includesEntireBlacklist(new URL('https://google.com'))).to.be.true;
       expect(blacklist.includesEntireBlacklist(new URL('https://github.com'))).to.be.false;
       expect(blacklist.includesEntireBlacklist(new URL('https://gist.github.com'))).to.be.true;
     });
 
     it('does not matches with partial blacklist', () => {
-      let blacklist = Blacklist.fromJSON(['google.com', { url: 'yahoo.com', keys: ['j', 'k'] }]);
+      const blacklist = Blacklist.fromJSON(['google.com', { url: 'yahoo.com', keys: ['j', 'k'] }]);
       expect(blacklist.includesEntireBlacklist(new URL('https://google.com'))).to.be.true;
       expect(blacklist.includesEntireBlacklist(new URL('https://yahoo.com'))).to.be.false;
     });
@@ -127,7 +127,7 @@ describe('Blacklist', () => {
 
   describe('#includesKeys', () => {
     it('matches with entire blacklist or keys in the partial blacklist', () => {
-      let blacklist = Blacklist.fromJSON([
+      const blacklist = Blacklist.fromJSON([
         'google.com',
         { url: 'github.com', keys: ['j', 'k'] },
       ]);
diff --git a/test/shared/settings/Key.test.ts b/test/shared/settings/Key.test.ts
index 91a47f8..3a1c86e 100644
--- a/test/shared/settings/Key.test.ts
+++ b/test/shared/settings/Key.test.ts
@@ -4,7 +4,7 @@ import Key from '../../../src/shared/settings/Key';
 describe("Key", () => {
   describe('fromMapKey', () => {
     it('return for X', () => {
-      let key = Key.fromMapKey('x');
+      const key = Key.fromMapKey('x');
       expect(key.key).to.equal('x');
       expect(key.shift).to.be.false;
       expect(key.ctrl).to.be.false;
@@ -13,7 +13,7 @@ describe("Key", () => {
     });
 
     it('return for Shift+X', () => {
-      let key = Key.fromMapKey('X');
+      const key = Key.fromMapKey('X');
       expect(key.key).to.equal('X');
       expect(key.shift).to.be.true;
       expect(key.ctrl).to.be.false;
@@ -22,7 +22,7 @@ describe("Key", () => {
     });
 
     it('return for Ctrl+X', () => {
-      let key = Key.fromMapKey('<C-X>');
+      const key = Key.fromMapKey('<C-X>');
       expect(key.key).to.equal('x');
       expect(key.shift).to.be.false;
       expect(key.ctrl).to.be.true;
@@ -31,7 +31,7 @@ describe("Key", () => {
     });
 
     it('returns for Ctrl+Meta+X', () => {
-      let key = Key.fromMapKey('<C-M-X>');
+      const key = Key.fromMapKey('<C-M-X>');
       expect(key.key).to.equal('x');
       expect(key.shift).to.be.false;
       expect(key.ctrl).to.be.true;
@@ -40,7 +40,7 @@ describe("Key", () => {
     });
 
     it('returns for Ctrl+Shift+x', () => {
-      let key = Key.fromMapKey('<C-S-x>');
+      const key = Key.fromMapKey('<C-S-x>');
       expect(key.key).to.equal('X');
       expect(key.shift).to.be.true;
       expect(key.ctrl).to.be.true;
@@ -49,7 +49,7 @@ describe("Key", () => {
     });
 
     it('returns for Shift+Esc', () => {
-      let key = Key.fromMapKey('<S-Esc>');
+      const key = Key.fromMapKey('<S-Esc>');
       expect(key.key).to.equal('Esc');
       expect(key.shift).to.be.true;
       expect(key.ctrl).to.be.false;
@@ -58,7 +58,7 @@ describe("Key", () => {
     });
 
     it('returns for Ctrl+Esc', () => {
-      let key = Key.fromMapKey('<C-Esc>');
+      const key = Key.fromMapKey('<C-Esc>');
       expect(key.key).to.equal('Esc');
       expect(key.shift).to.be.false;
       expect(key.ctrl).to.be.true;
@@ -67,7 +67,7 @@ describe("Key", () => {
     });
 
     it('returns for Ctrl+Esc', () => {
-      let key = Key.fromMapKey('<C-Space>');
+      const key = Key.fromMapKey('<C-Space>');
       expect(key.key).to.equal('Space');
       expect(key.shift).to.be.false;
       expect(key.ctrl).to.be.true;
diff --git a/test/shared/settings/Keymaps.test.ts b/test/shared/settings/Keymaps.test.ts
index 9e4109f..dcea6e4 100644
--- a/test/shared/settings/Keymaps.test.ts
+++ b/test/shared/settings/Keymaps.test.ts
@@ -4,12 +4,12 @@ import { expect } from 'chai';
 describe('Keymaps', () => {
   describe('#valueOf', () => {
     it('returns empty object by empty settings', () => {
-      let keymaps = Keymaps.fromJSON({}).toJSON();
+      const keymaps = Keymaps.fromJSON({}).toJSON();
       expect(keymaps).to.be.empty;
     });
 
     it('returns keymaps by valid settings', () => {
-      let keymaps = Keymaps.fromJSON({
+      const keymaps = Keymaps.fromJSON({
         k: { type: "scroll.vertically", count: -1 },
         j: { type: "scroll.vertically", count: 1 },
       }).toJSON();
@@ -27,7 +27,7 @@ describe('Keymaps', () => {
 
   describe('#combine', () => {
     it('returns combined keymaps', () => {
-      let keymaps = Keymaps.fromJSON({
+      const keymaps = Keymaps.fromJSON({
         k: { type: "scroll.vertically", count: -1 },
         j: { type: "scroll.vertically", count: 1 },
       }).combine(Keymaps.fromJSON({
@@ -35,7 +35,7 @@ describe('Keymaps', () => {
         N: { type: "find.prev" },
       }));
 
-      let entries = keymaps.entries().sort(([name1], [name2]) => name1.localeCompare(name2));
+      const entries = keymaps.entries().sort(([name1], [name2]) => name1.localeCompare(name2));
       expect(entries).deep.equals([
         ['j', { type: "scroll.vertically", count: 1 }],
         ['k', { type: "scroll.vertically", count: -1 }],
@@ -45,7 +45,7 @@ describe('Keymaps', () => {
     });
 
     it('overrides current keymaps', () => {
-      let keymaps = Keymaps.fromJSON({
+      const keymaps = Keymaps.fromJSON({
         k: { type: "scroll.vertically", count: -1 },
         j: { type: "scroll.vertically", count: 1 },
       }).combine(Keymaps.fromJSON({
@@ -53,7 +53,7 @@ describe('Keymaps', () => {
         j: { type: "find.prev" },
       }));
 
-      let entries = keymaps.entries().sort(([name1], [name2]) => name1.localeCompare(name2));
+      const entries = keymaps.entries().sort(([name1], [name2]) => name1.localeCompare(name2));
       expect(entries).deep.equals([
         ['j', { type: "find.prev" }],
         ['k', { type: "scroll.vertically", count: -1 }],
diff --git a/test/shared/settings/Properties.test.ts b/test/shared/settings/Properties.test.ts
index 609a565..4639839 100644
--- a/test/shared/settings/Properties.test.ts
+++ b/test/shared/settings/Properties.test.ts
@@ -4,7 +4,7 @@ import { expect } from 'chai';
 describe('Properties', () => {
   describe('#propertiesValueOf', () => {
     it('returns with default properties by empty settings', () => {
-      let props = Properties.fromJSON({});
+      const props = Properties.fromJSON({});
       expect(props).to.deep.equal({
         hintchars: "abcdefghijklmnopqrstuvwxyz",
         smoothscroll: false,
@@ -13,7 +13,7 @@ describe('Properties', () => {
     });
 
     it('returns properties by valid settings', () => {
-      let props = Properties.fromJSON({
+      const props = Properties.fromJSON({
         hintchars: "abcdefgh",
         smoothscroll: false,
         complete: "sbh"
diff --git a/test/shared/settings/Search.test.ts b/test/shared/settings/Search.test.ts
index 51cd3eb..8bd8d89 100644
--- a/test/shared/settings/Search.test.ts
+++ b/test/shared/settings/Search.test.ts
@@ -3,7 +3,7 @@ import { expect } from 'chai';
 
 describe('Search', () => {
   it('returns search settings by valid settings', () => {
-    let search = Search.fromJSON({
+    const search = Search.fromJSON({
       default: 'google',
       engines: {
         'google': 'https://google.com/search?q={}',
diff --git a/test/shared/settings/Settings.test.ts b/test/shared/settings/Settings.test.ts
index ab6af04..658132c 100644
--- a/test/shared/settings/Settings.test.ts
+++ b/test/shared/settings/Settings.test.ts
@@ -4,7 +4,7 @@ import { expect } from 'chai';
 describe('Settings', () => {
   describe('#valueOf', () => {
     it('returns settings by valid settings', () => {
-      let x = Settings.fromJSON({
+      const x = Settings.fromJSON({
         keymaps: {},
         "search": {
           "default": "google",
@@ -39,7 +39,7 @@ describe('Settings', () => {
     });
 
     it('sets default settings', () => {
-      let value = Settings.fromJSON({});
+      const value = Settings.fromJSON({});
       expect(value.keymaps.toJSON()).to.not.be.empty;
       expect(value.properties.toJSON()).to.not.be.empty;
       expect(value.search.defaultEngine).to.be.a('string');