Add and configure ESLint and update configuration for Prettier (#341)

* Turn on ESLint and update Prettier

* Update eslint config

* Update eslint config

* Update dependencies

* Update ESLint and Prettier configurations

* update package.json

* Update prettier command

* Update prettier config file

* Change CRLF to LF

* Update docs

* Update docs

.eslintignore

@@ -0,0 +1,6 @@
+# Ignore list
+/*
+
+# Do not ignore these folders:
+!__tests__/
+!src/

.eslintrc.js

@@ -0,0 +1,49 @@
+module.exports = {
+  extends: [
+    'eslint:recommended',
+    'plugin:@typescript-eslint/recommended',
+    'plugin:eslint-plugin-jest/recommended',
+    'eslint-config-prettier'
+  ],
+  parser: '@typescript-eslint/parser',
+  plugins: ['@typescript-eslint', 'eslint-plugin-jest'],
+  rules: {
+    '@typescript-eslint/no-require-imports': 'error',
+    '@typescript-eslint/no-non-null-assertion': 'off',
+    '@typescript-eslint/no-explicit-any': 'off',
+    '@typescript-eslint/no-empty-function': 'off',
+    '@typescript-eslint/ban-ts-comment': [
+      'error',
+      {
+        'ts-ignore': 'allow-with-description'
+      }
+    ],
+    'no-console': 'error',
+    'yoda': 'error',
+    'prefer-const': [
+      'error',
+      {
+        destructuring: 'all'
+      }
+    ],
+    'no-control-regex': 'off',
+    'no-constant-condition': ['error', {checkLoops: false}]
+  },
+  overrides: [
+    {
+      files: ['**/*{test,spec}.ts'],
+      rules: {
+        '@typescript-eslint/no-unused-vars': 'off',
+        'jest/no-standalone-expect': 'off',
+        'jest/no-conditional-expect': 'off',
+        'no-console': 'off',
+
+      }
+    }
+  ],
+  env: {
+    node: true,
+    es6: true,
+    'jest/globals': true
+  }
+};

.gitattributes

@@ -1,2 +1,2 @@
-* text=auto
+* text=auto eol=lf
 .licenses/** -diff linguist-generated=true

.github/ISSUE_TEMPLATE/config.yml

@@ -1 +1 @@
-blank_issues_enabled: false
+blank_issues_enabled: false

.github/workflows/basic-validation.yml

@@ -13,4 +13,4 @@ on:
 jobs:
   call-basic-validation:
     name: Basic validation
-    uses: actions/reusable-workflows/.github/workflows/basic-validation.yml@main
+    uses: actions/reusable-workflows/.github/workflows/basic-validation.yml@main

.github/workflows/check-dist.yml

@@ -14,4 +14,4 @@ on:
 jobs:
   call-check-dist:
     name: Check dist/
-    uses: actions/reusable-workflows/.github/workflows/check-dist.yml@main
+    uses: actions/reusable-workflows/.github/workflows/check-dist.yml@main

.github/workflows/codeql-analysis.yml

@@ -2,13 +2,13 @@ name: CodeQL analysis
 
 on:
   push:
-    branches: [ main ]
+    branches: [main]
   pull_request:
-    branches: [ main ]
+    branches: [main]
   schedule:
     - cron: '0 3 * * 0'
 
 jobs:
   call-codeQL-analysis:
-    name: CodeQL analysis 
+    name: CodeQL analysis
-    uses: actions/reusable-workflows/.github/workflows/codeql-analysis.yml@main
+    uses: actions/reusable-workflows/.github/workflows/codeql-analysis.yml@main

.github/workflows/licensed.yml

@@ -11,4 +11,4 @@ on:
 jobs:
   call-licensed:
     name: Licensed
-    uses: actions/reusable-workflows/.github/workflows/licensed.yml@main
+    uses: actions/reusable-workflows/.github/workflows/licensed.yml@main

.github/workflows/versions.yml

@@ -42,7 +42,7 @@ jobs:
           go-version: oldstable
       - name: Verify Go
         run: go version
-  
+
   aliases-arch:
     runs-on: ${{ matrix.os }}
     strategy:
@@ -52,8 +52,8 @@ jobs:
         version: [stable, oldstable]
         architecture: [x64, x32]
         exclude:
-        - os: macos-latest
+          - os: macos-latest
-          architecture: x32
+            architecture: x32
     steps:
       - uses: actions/checkout@v3
       - name: Setup Go ${{ matrix.version }} ${{ matrix.architecture }}

.prettierignore

@@ -0,0 +1,7 @@
+# Ignore list
+/*
+
+# Do not ignore these folders:
+!__tests__/
+!.github/
+!src/

.prettierrc.js

@@ -0,0 +1,10 @@
+module.exports = {
+  printWidth: 80,
+  tabWidth: 2,
+  useTabs: false,
+  semi: true,
+  singleQuote: true,
+  trailingComma: 'none',
+  bracketSpacing: false,
+  arrowParens: 'avoid'
+};

.prettierrc.json

@@ -1,11 +0,0 @@
-{
-    "printWidth": 80,
-    "tabWidth": 2,
-    "useTabs": false,
-    "semi": true,
-    "singleQuote": true,
-    "trailingComma": "none",
-    "bracketSpacing": false,
-    "arrowParens": "avoid",
-    "parser": "typescript"
-  }

__tests__/cache-restore.test.ts

@@ -8,14 +8,14 @@ import {PackageManagerInfo} from '../src/package-managers';
 
 describe('restoreCache', () => {
   //Arrange
-  let hashFilesSpy = jest.spyOn(glob, 'hashFiles');
+  const hashFilesSpy = jest.spyOn(glob, 'hashFiles');
-  let getCacheDirectoryPathSpy = jest.spyOn(
+  const getCacheDirectoryPathSpy = jest.spyOn(
     cacheUtils,
     'getCacheDirectoryPath'
   );
-  let restoreCacheSpy = jest.spyOn(cache, 'restoreCache');
+  const restoreCacheSpy = jest.spyOn(cache, 'restoreCache');
-  let infoSpy = jest.spyOn(core, 'info');
+  const infoSpy = jest.spyOn(core, 'info');
-  let setOutputSpy = jest.spyOn(core, 'setOutput');
+  const setOutputSpy = jest.spyOn(core, 'setOutput');
 
   const versionSpec = '1.13.1';
   const packageManager = 'default';
@@ -40,13 +40,13 @@ describe('restoreCache', () => {
     });
 
     //Act + Assert
-    expect(async () => {
+    await expect(async () => {
       await cacheRestore.restoreCache(
         versionSpec,
         packageManager,
         cacheDependencyPath
       );
-    }).rejects.toThrowError(
+    }).rejects.toThrow(
       'Some specified paths were not resolved, unable to cache dependencies.'
     );
   });
@@ -71,7 +71,7 @@ describe('restoreCache', () => {
       packageManager,
       cacheDependencyPath
     );
-    expect(infoSpy).toBeCalledWith(`Cache is not found`);
+    expect(infoSpy).toHaveBeenCalledWith(`Cache is not found`);
   });
 
   it('should set output if cache hit is occured', async () => {
@@ -94,6 +94,6 @@ describe('restoreCache', () => {
       packageManager,
       cacheDependencyPath
     );
-    expect(setOutputSpy).toBeCalledWith('cache-hit', true);
+    expect(setOutputSpy).toHaveBeenCalledWith('cache-hit', true);
   });
 });

__tests__/cache-utils.test.ts

@@ -6,7 +6,7 @@ import {PackageManagerInfo} from '../src/package-managers';
 
 describe('getCommandOutput', () => {
   //Arrange
-  let getExecOutputSpy = jest.spyOn(exec, 'getExecOutput');
+  const getExecOutputSpy = jest.spyOn(exec, 'getExecOutput');
 
   it('should return trimmed stdout in case of successful exit code', async () => {
     //Arrange
@@ -36,7 +36,7 @@ describe('getCommandOutput', () => {
     });
 
     //Act + Assert
-    expect(async () => {
+    await expect(async () => {
       await cacheUtils.getCommandOutput('command');
     }).rejects.toThrow();
   });
@@ -62,7 +62,7 @@ describe('getPackageManagerInfo', () => {
     const packageManagerName = 'invalidName';
 
     //Act + Assert
-    expect(async () => {
+    await expect(async () => {
       await cacheUtils.getPackageManagerInfo(packageManagerName);
     }).rejects.toThrow();
   });
@@ -70,7 +70,7 @@ describe('getPackageManagerInfo', () => {
 
 describe('getCacheDirectoryPath', () => {
   //Arrange
-  let getExecOutputSpy = jest.spyOn(exec, 'getExecOutput');
+  const getExecOutputSpy = jest.spyOn(exec, 'getExecOutput');
 
   const validPackageManager: PackageManagerInfo = {
     dependencyFilePattern: 'go.sum',
@@ -123,7 +123,7 @@ describe('getCacheDirectoryPath', () => {
     });
 
     //Act + Assert
-    expect(async () => {
+    await expect(async () => {
       await cacheUtils.getCacheDirectoryPath(validPackageManager);
     }).rejects.toThrow();
   });
@@ -136,7 +136,7 @@ describe('getCacheDirectoryPath', () => {
     });
 
     //Act + Assert
-    expect(async () => {
+    await expect(async () => {
       await cacheUtils.getCacheDirectoryPath(validPackageManager);
     }).rejects.toThrow();
   });
@@ -144,8 +144,8 @@ describe('getCacheDirectoryPath', () => {
 
 describe('isCacheFeatureAvailable', () => {
   //Arrange
-  let isFeatureAvailableSpy = jest.spyOn(cache, 'isFeatureAvailable');
+  const isFeatureAvailableSpy = jest.spyOn(cache, 'isFeatureAvailable');
-  let warningSpy = jest.spyOn(core, 'warning');
+  const warningSpy = jest.spyOn(core, 'warning');
 
   it('should return true when cache feature is available', () => {
     //Arrange
@@ -153,16 +153,14 @@ describe('isCacheFeatureAvailable', () => {
       return true;
     });
 
-    let functionResult;
-
     //Act
-    functionResult = cacheUtils.isCacheFeatureAvailable();
+    const functionResult = cacheUtils.isCacheFeatureAvailable();
 
     //Assert
     expect(functionResult).toBeTruthy();
   });
 
-  it('should warn when cache feature is unavailable and GHES is not used ', () => {
+  it('should warn when cache feature is unavailable and GHES is not used', () => {
     //Arrange
     isFeatureAvailableSpy.mockImplementation(() => {
       return false;
@@ -170,7 +168,7 @@ describe('isCacheFeatureAvailable', () => {
 
     process.env['GITHUB_SERVER_URL'] = 'https://github.com';
 
-    let warningMessage =
+    const warningMessage =
       'The runner was not able to contact the cache service. Caching will be skipped';
 
     //Act
@@ -188,10 +186,8 @@ describe('isCacheFeatureAvailable', () => {
 
     process.env['GITHUB_SERVER_URL'] = 'https://github.com';
 
-    let functionResult;
-
     //Act
-    functionResult = cacheUtils.isCacheFeatureAvailable();
+    const functionResult = cacheUtils.isCacheFeatureAvailable();
 
     //Assert
     expect(functionResult).toBeFalsy();
@@ -205,7 +201,7 @@ describe('isCacheFeatureAvailable', () => {
 
     process.env['GITHUB_SERVER_URL'] = 'https://nongithub.com';
 
-    let warningMessage =
+    const warningMessage =
       'Cache action is only supported on GHES version >= 3.5. If you are on version >=3.5 Please check with GHES admin if Actions cache service is enabled or not.';
 
     //Act + Assert

__tests__/setup-go.test.ts

@@ -8,13 +8,13 @@ import path from 'path';
 import * as main from '../src/main';
 import * as im from '../src/installer';
 
-let goJsonData = require('./data/golang-dl.json');
+import goJsonData from './data/golang-dl.json';
-let matchers = require('../matchers.json');
+import matchers from '../matchers.json';
-let goTestManifest = require('./data/versions-manifest.json');
+import goTestManifest from './data/versions-manifest.json';
-let matcherPattern = matchers.problemMatcher[0].pattern[0];
+const matcherPattern = matchers.problemMatcher[0].pattern[0];
-let matcherRegExp = new RegExp(matcherPattern.regexp);
+const matcherRegExp = new RegExp(matcherPattern.regexp);
-let win32Join = path.win32.join;
+const win32Join = path.win32.join;
-let posixJoin = path.posix.join;
+const posixJoin = path.posix.join;
 
 describe('setup-go', () => {
   let inputs = {} as any;
@@ -133,7 +133,7 @@ describe('setup-go', () => {
     os.platform = 'darwin';
     os.arch = 'x64';
 
-    let match = await im.getInfoFromManifest('1.9.7', true, 'mocktoken');
+    const match = await im.getInfoFromManifest('1.9.7', true, 'mocktoken');
     expect(match).toBeDefined();
     expect(match!.resolvedVersion).toBe('1.9.7');
     expect(match!.type).toBe('manifest');
@@ -146,7 +146,7 @@ describe('setup-go', () => {
     os.platform = 'linux';
     os.arch = 'x64';
 
-    let match = await im.getInfoFromManifest('1.9.7', true, 'mocktoken');
+    const match = await im.getInfoFromManifest('1.9.7', true, 'mocktoken');
     expect(match).toBeDefined();
     expect(match!.resolvedVersion).toBe('1.9.7');
     expect(match!.type).toBe('manifest');
@@ -159,7 +159,7 @@ describe('setup-go', () => {
     os.platform = 'win32';
     os.arch = 'x64';
 
-    let match = await im.getInfoFromManifest('1.9.7', true, 'mocktoken');
+    const match = await im.getInfoFromManifest('1.9.7', true, 'mocktoken');
     expect(match).toBeDefined();
     expect(match!.resolvedVersion).toBe('1.9.7');
     expect(match!.type).toBe('manifest');
@@ -173,11 +173,11 @@ describe('setup-go', () => {
     os.arch = 'x64';
 
     // spec: 1.13.0 => 1.13
-    let match: im.IGoVersion | undefined = await im.findMatch('1.13.0');
+    const match: im.IGoVersion | undefined = await im.findMatch('1.13.0');
     expect(match).toBeDefined();
-    let version: string = match ? match.version : '';
+    const version: string = match ? match.version : '';
     expect(version).toBe('go1.13');
-    let fileName = match ? match.files[0].filename : '';
+    const fileName = match ? match.files[0].filename : '';
     expect(fileName).toBe('go1.13.darwin-amd64.tar.gz');
   });
 
@@ -186,11 +186,11 @@ describe('setup-go', () => {
     os.arch = 'x64';
 
     // spec: 1.13 => 1.13.7 (latest)
-    let match: im.IGoVersion | undefined = await im.findMatch('1.13');
+    const match: im.IGoVersion | undefined = await im.findMatch('1.13');
     expect(match).toBeDefined();
-    let version: string = match ? match.version : '';
+    const version: string = match ? match.version : '';
     expect(version).toBe('go1.13.7');
-    let fileName = match ? match.files[0].filename : '';
+    const fileName = match ? match.files[0].filename : '';
     expect(fileName).toBe('go1.13.7.linux-amd64.tar.gz');
   });
 
@@ -199,11 +199,11 @@ describe('setup-go', () => {
     os.arch = 'x64';
 
     // spec: ^1.13.6 => 1.13.7
-    let match: im.IGoVersion | undefined = await im.findMatch('^1.13.6');
+    const match: im.IGoVersion | undefined = await im.findMatch('^1.13.6');
     expect(match).toBeDefined();
-    let version: string = match ? match.version : '';
+    const version: string = match ? match.version : '';
     expect(version).toBe('go1.13.7');
-    let fileName = match ? match.files[0].filename : '';
+    const fileName = match ? match.files[0].filename : '';
     expect(fileName).toBe('go1.13.7.linux-amd64.tar.gz');
   });
 
@@ -212,11 +212,11 @@ describe('setup-go', () => {
     os.arch = 'x32';
 
     // spec: 1 => 1.13.7 (latest)
-    let match: im.IGoVersion | undefined = await im.findMatch('1');
+    const match: im.IGoVersion | undefined = await im.findMatch('1');
     expect(match).toBeDefined();
-    let version: string = match ? match.version : '';
+    const version: string = match ? match.version : '';
     expect(version).toBe('go1.13.7');
-    let fileName = match ? match.files[0].filename : '';
+    const fileName = match ? match.files[0].filename : '';
     expect(fileName).toBe('go1.13.7.windows-386.zip');
   });
 
@@ -225,11 +225,11 @@ describe('setup-go', () => {
     os.arch = 'x64';
 
     // spec: 1.14, stable=false => go1.14rc1
-    let match: im.IGoVersion | undefined = await im.findMatch('1.14.0-rc.1');
+    const match: im.IGoVersion | undefined = await im.findMatch('1.14.0-rc.1');
     expect(match).toBeDefined();
-    let version: string = match ? match.version : '';
+    const version: string = match ? match.version : '';
     expect(version).toBe('go1.14rc1');
-    let fileName = match ? match.files[0].filename : '';
+    const fileName = match ? match.files[0].filename : '';
     expect(fileName).toBe('go1.14rc1.linux-amd64.tar.gz');
   });
 
@@ -237,7 +237,7 @@ describe('setup-go', () => {
     inputs['go-version'] = '1.13.0';
     inputs.stable = 'true';
 
-    let toolPath = path.normalize('/cache/go/1.13.0/x64');
+    const toolPath = path.normalize('/cache/go/1.13.0/x64');
     findSpy.mockImplementation(() => toolPath);
     await main.run();
 
@@ -249,7 +249,7 @@ describe('setup-go', () => {
 
     inSpy.mockImplementation(name => inputs[name]);
 
-    let toolPath = path.normalize('/cache/go/1.13.0/x64');
+    const toolPath = path.normalize('/cache/go/1.13.0/x64');
     findSpy.mockImplementation(() => toolPath);
     await main.run();
 
@@ -260,10 +260,10 @@ describe('setup-go', () => {
     inputs['go-version'] = '1.13.0';
     inSpy.mockImplementation(name => inputs[name]);
 
-    let toolPath = path.normalize('/cache/go/1.13.0/x64');
+    const toolPath = path.normalize('/cache/go/1.13.0/x64');
     findSpy.mockImplementation(() => toolPath);
 
-    let vars: {[key: string]: string} = {};
+    const vars: {[key: string]: string} = {};
     exportVarSpy.mockImplementation((name: string, val: string) => {
       vars[name] = val;
     });
@@ -276,10 +276,10 @@ describe('setup-go', () => {
     inputs['go-version'] = '1.8';
     inSpy.mockImplementation(name => inputs[name]);
 
-    let toolPath = path.normalize('/cache/go/1.8.0/x64');
+    const toolPath = path.normalize('/cache/go/1.8.0/x64');
     findSpy.mockImplementation(() => toolPath);
 
-    let vars: {[key: string]: string} = {};
+    const vars: {[key: string]: string} = {};
     exportVarSpy.mockImplementation((name: string, val: string) => {
       vars[name] = val;
     });
@@ -293,7 +293,7 @@ describe('setup-go', () => {
   it('finds a version of go already in the cache', async () => {
     inputs['go-version'] = '1.13.0';
 
-    let toolPath = path.normalize('/cache/go/1.13.0/x64');
+    const toolPath = path.normalize('/cache/go/1.13.0/x64');
     findSpy.mockImplementation(() => toolPath);
     await main.run();
 
@@ -302,16 +302,16 @@ describe('setup-go', () => {
 
   it('finds a version in the cache and adds it to the path', async () => {
     inputs['go-version'] = '1.13.0';
-    let toolPath = path.normalize('/cache/go/1.13.0/x64');
+    const toolPath = path.normalize('/cache/go/1.13.0/x64');
     findSpy.mockImplementation(() => toolPath);
     await main.run();
 
-    let expPath = path.join(toolPath, 'bin');
+    const expPath = path.join(toolPath, 'bin');
     expect(cnSpy).toHaveBeenCalledWith(`::add-path::${expPath}${osm.EOL}`);
   });
 
   it('handles unhandled error and reports error', async () => {
-    let errMsg = 'unhandled error message';
+    const errMsg = 'unhandled error message';
     inputs['go-version'] = '1.13.0';
 
     findSpy.mockImplementation(() => {
@@ -329,12 +329,12 @@ describe('setup-go', () => {
 
     findSpy.mockImplementation(() => '');
     dlSpy.mockImplementation(() => '/some/temp/path');
-    let toolPath = path.normalize('/cache/go/1.13.0/x64');
+    const toolPath = path.normalize('/cache/go/1.13.0/x64');
     extractTarSpy.mockImplementation(() => '/some/other/temp/path');
     cacheSpy.mockImplementation(() => toolPath);
     await main.run();
 
-    let expPath = path.join(toolPath, 'bin');
+    const expPath = path.join(toolPath, 'bin');
 
     expect(dlSpy).toHaveBeenCalled();
     expect(extractTarSpy).toHaveBeenCalled();
@@ -352,12 +352,12 @@ describe('setup-go', () => {
     dlSpy.mockImplementation(() => 'C:\\temp\\some\\path');
     extractZipSpy.mockImplementation(() => 'C:\\temp\\some\\other\\path');
 
-    let toolPath = path.normalize('C:\\cache\\go\\1.13.0\\x64');
+    const toolPath = path.normalize('C:\\cache\\go\\1.13.0\\x64');
     cacheSpy.mockImplementation(() => toolPath);
 
     await main.run();
 
-    let expPath = path.win32.join(toolPath, 'bin');
+    const expPath = path.win32.join(toolPath, 'bin');
     expect(dlSpy).toHaveBeenCalledWith(
       'https://storage.googleapis.com/golang/go1.13.1.windows-amd64.zip',
       'C:\\temp\\go1.13.1.windows-amd64.zip',
@@ -384,25 +384,25 @@ describe('setup-go', () => {
     os.platform = 'linux';
     os.arch = 'x64';
 
-    let versionSpec = '1.12.16';
+    const versionSpec = '1.12.16';
 
     inputs['go-version'] = versionSpec;
     inputs['token'] = 'faketoken';
 
-    let expectedUrl =
+    const expectedUrl =
       'https://github.com/actions/go-versions/releases/download/1.12.16-20200616.20/go-1.12.16-linux-x64.tar.gz';
 
     // ... but not in the local cache
     findSpy.mockImplementation(() => '');
 
     dlSpy.mockImplementation(async () => '/some/temp/path');
-    let toolPath = path.normalize('/cache/go/1.12.16/x64');
+    const toolPath = path.normalize('/cache/go/1.12.16/x64');
     extractTarSpy.mockImplementation(async () => '/some/other/temp/path');
     cacheSpy.mockImplementation(async () => toolPath);
 
     await main.run();
 
-    let expPath = path.join(toolPath, 'bin');
+    const expPath = path.join(toolPath, 'bin');
 
     expect(dlSpy).toHaveBeenCalled();
     expect(extractTarSpy).toHaveBeenCalled();
@@ -421,25 +421,25 @@ describe('setup-go', () => {
     os.platform = 'linux';
     os.arch = 'x64';
 
-    let versionSpec = '1.12';
+    const versionSpec = '1.12';
 
     inputs['go-version'] = versionSpec;
     inputs['token'] = 'faketoken';
 
-    let expectedUrl =
+    const expectedUrl =
       'https://github.com/actions/go-versions/releases/download/1.12.17-20200616.21/go-1.12.17-linux-x64.tar.gz';
 
     // ... but not in the local cache
     findSpy.mockImplementation(() => '');
 
     dlSpy.mockImplementation(async () => '/some/temp/path');
-    let toolPath = path.normalize('/cache/go/1.12.17/x64');
+    const toolPath = path.normalize('/cache/go/1.12.17/x64');
     extractTarSpy.mockImplementation(async () => '/some/other/temp/path');
     cacheSpy.mockImplementation(async () => toolPath);
 
     await main.run();
 
-    let expPath = path.join(toolPath, 'bin');
+    const expPath = path.join(toolPath, 'bin');
 
     expect(dlSpy).toHaveBeenCalled();
     expect(extractTarSpy).toHaveBeenCalled();
@@ -458,7 +458,7 @@ describe('setup-go', () => {
     os.platform = 'linux';
     os.arch = 'x64';
 
-    let versionSpec = '1.12.14';
+    const versionSpec = '1.12.14';
 
     inputs['go-version'] = versionSpec;
     inputs['token'] = 'faketoken';
@@ -467,13 +467,13 @@ describe('setup-go', () => {
     findSpy.mockImplementation(() => '');
 
     dlSpy.mockImplementation(async () => '/some/temp/path');
-    let toolPath = path.normalize('/cache/go/1.12.14/x64');
+    const toolPath = path.normalize('/cache/go/1.12.14/x64');
     extractTarSpy.mockImplementation(async () => '/some/other/temp/path');
     cacheSpy.mockImplementation(async () => toolPath);
 
     await main.run();
 
-    let expPath = path.join(toolPath, 'bin');
+    const expPath = path.join(toolPath, 'bin');
     expect(logSpy).toHaveBeenCalledWith('Setup go version spec 1.12.14');
     expect(findSpy).toHaveBeenCalled();
     expect(logSpy).toHaveBeenCalledWith('Attempting to download 1.12.14...');
@@ -489,7 +489,7 @@ describe('setup-go', () => {
   });
 
   it('reports a failed download', async () => {
-    let errMsg = 'unhandled download message';
+    const errMsg = 'unhandled download message';
     os.platform = 'linux';
     os.arch = 'x64';
 
@@ -510,7 +510,7 @@ describe('setup-go', () => {
     whichSpy.mockImplementation(async () => {
       return '';
     });
-    let added = await main.addBinToPath();
+    const added = await main.addBinToPath();
     expect(added).toBeFalsy();
   });
 
@@ -528,8 +528,8 @@ describe('setup-go', () => {
       return false;
     });
 
-    let added = await main.addBinToPath();
+    const added = await main.addBinToPath();
-    expect(added).toBeTruthy;
+    expect(added).toBeTruthy();
   });
 
   interface Annotation {
@@ -543,9 +543,9 @@ describe('setup-go', () => {
   // problem matcher regex pattern tests
 
   function testMatch(line: string): Annotation {
-    let annotation = <Annotation>{};
+    const annotation = <Annotation>{};
 
-    let match = matcherRegExp.exec(line);
+    const match = matcherRegExp.exec(line);
     if (match) {
       annotation.line = parseInt(match[matcherPattern.line], 10);
       annotation.column = parseInt(match[matcherPattern.column], 10);
@@ -557,8 +557,8 @@ describe('setup-go', () => {
   }
 
   it('matches on relative unix path', async () => {
-    let line = './main.go:13:2: undefined: fmt.Printl';
+    const line = './main.go:13:2: undefined: fmt.Printl';
-    let annotation = testMatch(line);
+    const annotation = testMatch(line);
     expect(annotation).toBeDefined();
     expect(annotation.line).toBe(13);
     expect(annotation.column).toBe(2);
@@ -567,8 +567,8 @@ describe('setup-go', () => {
   });
 
   it('matches on unix path up the tree', async () => {
-    let line = '../main.go:13:2: undefined: fmt.Printl';
+    const line = '../main.go:13:2: undefined: fmt.Printl';
-    let annotation = testMatch(line);
+    const annotation = testMatch(line);
     expect(annotation).toBeDefined();
     expect(annotation.line).toBe(13);
     expect(annotation.column).toBe(2);
@@ -577,8 +577,8 @@ describe('setup-go', () => {
   });
 
   it('matches on unix path down the tree', async () => {
-    let line = 'foo/main.go:13:2: undefined: fmt.Printl';
+    const line = 'foo/main.go:13:2: undefined: fmt.Printl';
-    let annotation = testMatch(line);
+    const annotation = testMatch(line);
     expect(annotation).toBeDefined();
     expect(annotation.line).toBe(13);
     expect(annotation.column).toBe(2);
@@ -587,8 +587,8 @@ describe('setup-go', () => {
   });
 
   it('matches on rooted unix path', async () => {
-    let line = '/assert.go:4:1: missing return at end of function';
+    const line = '/assert.go:4:1: missing return at end of function';
-    let annotation = testMatch(line);
+    const annotation = testMatch(line);
     expect(annotation).toBeDefined();
     expect(annotation.line).toBe(4);
     expect(annotation.column).toBe(1);
@@ -597,8 +597,8 @@ describe('setup-go', () => {
   });
 
   it('matches on unix path with spaces', async () => {
-    let line = '   ./assert.go:5:2: missing return at end of function   ';
+    const line = '   ./assert.go:5:2: missing return at end of function   ';
-    let annotation = testMatch(line);
+    const annotation = testMatch(line);
     expect(annotation).toBeDefined();
     expect(annotation.line).toBe(5);
     expect(annotation.column).toBe(2);
@@ -607,8 +607,8 @@ describe('setup-go', () => {
   });
 
   it('matches on unix path with tabs', async () => {
-    let line = '\t./assert.go:5:2: missing return at end of function   ';
+    const line = '\t./assert.go:5:2: missing return at end of function   ';
-    let annotation = testMatch(line);
+    const annotation = testMatch(line);
     expect(annotation).toBeDefined();
     expect(annotation.line).toBe(5);
     expect(annotation.column).toBe(2);
@@ -617,8 +617,8 @@ describe('setup-go', () => {
   });
 
   it('matches on relative windows path', async () => {
-    let line = '.\\main.go:13:2: undefined: fmt.Printl';
+    const line = '.\\main.go:13:2: undefined: fmt.Printl';
-    let annotation = testMatch(line);
+    const annotation = testMatch(line);
     expect(annotation).toBeDefined();
     expect(annotation.line).toBe(13);
     expect(annotation.column).toBe(2);
@@ -627,8 +627,8 @@ describe('setup-go', () => {
   });
 
   it('matches on windows path up the tree', async () => {
-    let line = '..\\main.go:13:2: undefined: fmt.Printl';
+    const line = '..\\main.go:13:2: undefined: fmt.Printl';
-    let annotation = testMatch(line);
+    const annotation = testMatch(line);
     expect(annotation).toBeDefined();
     expect(annotation.line).toBe(13);
     expect(annotation.column).toBe(2);
@@ -730,7 +730,7 @@ describe('setup-go', () => {
       os.platform = 'linux';
       os.arch = 'x64';
 
-      let versionSpec = '1.13';
+      const versionSpec = '1.13';
 
       inputs['go-version'] = versionSpec;
       inputs['check-latest'] = true;
@@ -741,13 +741,13 @@ describe('setup-go', () => {
       findSpy.mockImplementation(() => '');
 
       dlSpy.mockImplementation(async () => '/some/temp/path');
-      let toolPath = path.normalize('/cache/go/1.13.7/x64');
+      const toolPath = path.normalize('/cache/go/1.13.7/x64');
       extractTarSpy.mockImplementation(async () => '/some/other/temp/path');
       cacheSpy.mockImplementation(async () => toolPath);
 
       await main.run();
 
-      let expPath = path.join(toolPath, 'bin');
+      const expPath = path.join(toolPath, 'bin');
 
       expect(dlSpy).toHaveBeenCalled();
       expect(extractTarSpy).toHaveBeenCalled();
@@ -767,7 +767,7 @@ describe('setup-go', () => {
       os.platform = 'linux';
       os.arch = 'x64';
 
-      let versionSpec = '1.13';
+      const versionSpec = '1.13';
 
       process.env['GITHUB_PATH'] = '';
 
@@ -784,13 +784,13 @@ describe('setup-go', () => {
       getAllVersionsSpy.mockImplementationOnce(() => undefined);
 
       dlSpy.mockImplementation(async () => '/some/temp/path');
-      let toolPath = path.normalize('/cache/go/1.13.7/x64');
+      const toolPath = path.normalize('/cache/go/1.13.7/x64');
       extractTarSpy.mockImplementation(async () => '/some/other/temp/path');
       cacheSpy.mockImplementation(async () => toolPath);
 
       await main.run();
 
-      let expPath = path.join(toolPath, 'bin');
+      const expPath = path.join(toolPath, 'bin');
 
       expect(logSpy).toHaveBeenCalledWith(
         `Failed to resolve version ${versionSpec} from manifest`
@@ -910,7 +910,7 @@ use .
         inputs['go-version'] = version;
         inputs['architecture'] = arch;
 
-        let expectedUrl =
+        const expectedUrl =
           platform === 'win32'
             ? `https://github.com/actions/go-versions/releases/download/${version}/go-${version}-${platform}-${arch}.${fileExtension}`
             : `https://storage.googleapis.com/golang/go${version}.${osSpec}-${arch}.${fileExtension}`;
@@ -919,7 +919,7 @@ use .
         findSpy.mockImplementation(() => '');
 
         dlSpy.mockImplementation(async () => '/some/temp/path');
-        let toolPath = path.normalize(`/cache/go/${version}/${arch}`);
+        const toolPath = path.normalize(`/cache/go/${version}/${arch}`);
         cacheSpy.mockImplementation(async () => toolPath);
 
         await main.run();
@@ -944,7 +944,7 @@ use .
         findSpy.mockImplementation(() => '');
 
         dlSpy.mockImplementation(async () => '/some/temp/path');
-        let toolPath = path.normalize(`/cache/go/${alias}/${arch}`);
+        const toolPath = path.normalize(`/cache/go/${alias}/${arch}`);
         cacheSpy.mockImplementation(async () => toolPath);
 
         await main.run();

dist/cache-save/index.js

@@ -60457,7 +60457,7 @@ const getPackageManagerInfo = (packageManager) => __awaiter(void 0, void 0, void
 });
 exports.getPackageManagerInfo = getPackageManagerInfo;
 const getCacheDirectoryPath = (packageManagerInfo) => __awaiter(void 0, void 0, void 0, function* () {
-    const pathList = yield Promise.all(packageManagerInfo.cacheFolderCommandList.map(command => exports.getCommandOutput(command)));
+    const pathList = yield Promise.all(packageManagerInfo.cacheFolderCommandList.map((command) => __awaiter(void 0, void 0, void 0, function* () { return exports.getCommandOutput(command); })));
     const cachePaths = pathList.filter(item => item);
     if (!cachePaths.length) {
         throw new Error(`Could not get cache folder paths.`);

dist/setup/index.js

@@ -63058,7 +63058,7 @@ const restoreCache = (versionSpec, packageManager, cacheDependencyPath) => __awa
 });
 exports.restoreCache = restoreCache;
 const findDependencyFile = (packageManager) => {
-    let dependencyFile = packageManager.dependencyFilePattern;
+    const dependencyFile = packageManager.dependencyFilePattern;
     const workspace = process.env.GITHUB_WORKSPACE;
     const rootContent = fs_1.default.readdirSync(workspace);
     const goSumFileExists = rootContent.includes(dependencyFile);
@@ -63130,7 +63130,7 @@ const getPackageManagerInfo = (packageManager) => __awaiter(void 0, void 0, void
 });
 exports.getPackageManagerInfo = getPackageManagerInfo;
 const getCacheDirectoryPath = (packageManagerInfo) => __awaiter(void 0, void 0, void 0, function* () {
-    const pathList = yield Promise.all(packageManagerInfo.cacheFolderCommandList.map(command => exports.getCommandOutput(command)));
+    const pathList = yield Promise.all(packageManagerInfo.cacheFolderCommandList.map((command) => __awaiter(void 0, void 0, void 0, function* () { return exports.getCommandOutput(command); })));
     const cachePaths = pathList.filter(item => item);
     if (!cachePaths.length) {
         throw new Error(`Could not get cache folder paths.`);
@@ -63229,7 +63229,7 @@ const utils_1 = __nccwpck_require__(1314);
 function getGo(versionSpec, checkLatest, auth, arch = os_1.default.arch()) {
     return __awaiter(this, void 0, void 0, function* () {
         let manifest;
-        let osPlat = os_1.default.platform();
+        const osPlat = os_1.default.platform();
         if (versionSpec === utils_1.StableReleaseAlias.Stable ||
             versionSpec === utils_1.StableReleaseAlias.OldStable) {
             manifest = yield getManifest(auth);
@@ -63255,8 +63255,7 @@ function getGo(versionSpec, checkLatest, auth, arch = os_1.default.arch()) {
             }
         }
         // check cache
-        let toolPath;
+        const toolPath = tc.find('go', versionSpec, arch);
-        toolPath = tc.find('go', versionSpec, arch);
         // If not found in cache, download
         if (toolPath) {
             core.info(`Found in cache @ ${toolPath}`);
@@ -63382,12 +63381,11 @@ function getInfoFromManifest(versionSpec, stable, auth, arch = os_1.default.arch
 exports.getInfoFromManifest = getInfoFromManifest;
 function getInfoFromDist(versionSpec, arch) {
     return __awaiter(this, void 0, void 0, function* () {
-        let version;
+        const version = yield findMatch(versionSpec, arch);
-        version = yield findMatch(versionSpec, arch);
         if (!version) {
             return null;
         }
-        let downloadUrl = `https://storage.googleapis.com/golang/${version.files[0].filename}`;
+        const downloadUrl = `https://storage.googleapis.com/golang/${version.files[0].filename}`;
         return {
             type: 'dist',
             downloadUrl: downloadUrl,
@@ -63409,8 +63407,8 @@ function findMatch(versionSpec, arch = os_1.default.arch()) {
         }
         let goFile;
         for (let i = 0; i < candidates.length; i++) {
-            let candidate = candidates[i];
+            const candidate = candidates[i];
-            let version = makeSemver(candidate.version);
+            const version = makeSemver(candidate.version);
             core.debug(`check ${version} satisfies ${versionSpec}`);
             if (semver.satisfies(version, versionSpec)) {
                 goFile = candidate.files.find(file => {
@@ -63454,8 +63452,8 @@ function makeSemver(version) {
     var _a;
     version = version.replace('go', '');
     version = version.replace('beta', '-beta.').replace('rc', '-rc.');
-    let parts = version.split('-');
+    const parts = version.split('-');
-    let semVersion = (_a = semver.coerce(parts[0])) === null || _a === void 0 ? void 0 : _a.version;
+    const semVersion = (_a = semver.coerce(parts[0])) === null || _a === void 0 ? void 0 : _a.version;
     if (!semVersion) {
         throw new Error(`The version: ${version} can't be changed to SemVer notation`);
     }
@@ -63481,8 +63479,8 @@ function parseGoVersionFile(versionFilePath) {
 exports.parseGoVersionFile = parseGoVersionFile;
 function resolveStableVersionDist(versionSpec, arch) {
     return __awaiter(this, void 0, void 0, function* () {
-        let archFilter = sys.getArch(arch);
+        const archFilter = sys.getArch(arch);
-        let platFilter = sys.getPlatform();
+        const platFilter = sys.getPlatform();
         const dlUrl = 'https://golang.org/dl/?mode=json&include=all';
         const candidates = yield module.exports.getVersionsDist(dlUrl);
         if (!candidates) {
@@ -63585,8 +63583,8 @@ function run() {
                 arch = os_1.default.arch();
             }
             if (versionSpec) {
-                let token = core.getInput('token');
+                const token = core.getInput('token');
-                let auth = !token ? undefined : `token ${token}`;
+                const auth = !token ? undefined : `token ${token}`;
                 const checkLatest = core.getBooleanInput('check-latest');
                 const installDir = yield installer.getGo(versionSpec, checkLatest, auth, arch);
                 const installDirVersion = path_1.default.basename(path_1.default.dirname(installDir));
@@ -63598,12 +63596,12 @@ function run() {
                     core.info('Setting GOROOT for Go version < 1.9');
                     core.exportVariable('GOROOT', installDir);
                 }
-                let added = yield addBinToPath();
+                const added = yield addBinToPath();
                 core.debug(`add bin ${added}`);
                 core.info(`Successfully set up Go version ${versionSpec}`);
             }
-            let goPath = yield io.which('go');
+            const goPath = yield io.which('go');
-            let goVersion = (child_process_1.default.execSync(`${goPath} version`) || '').toString();
+            const goVersion = (child_process_1.default.execSync(`${goPath} version`) || '').toString();
             if (cache && cache_utils_1.isCacheFeatureAvailable()) {
                 const packageManager = 'default';
                 const cacheDependencyPath = core.getInput('cache-dependency-path');
@@ -63616,7 +63614,7 @@ function run() {
             core.info(goVersion);
             core.setOutput('go-version', parseGoVersion(goVersion));
             core.startGroup('go env');
-            let goEnv = (child_process_1.default.execSync(`${goPath} env`) || '').toString();
+            const goEnv = (child_process_1.default.execSync(`${goPath} env`) || '').toString();
             core.info(goEnv);
             core.endGroup();
         }
@@ -63629,22 +63627,22 @@ exports.run = run;
 function addBinToPath() {
     return __awaiter(this, void 0, void 0, function* () {
         let added = false;
-        let g = yield io.which('go');
+        const g = yield io.which('go');
         core.debug(`which go :${g}:`);
         if (!g) {
             core.debug('go not in the path');
             return added;
         }
-        let buf = child_process_1.default.execSync('go env GOPATH');
+        const buf = child_process_1.default.execSync('go env GOPATH');
         if (buf.length > 1) {
-            let gp = buf.toString().trim();
+            const gp = buf.toString().trim();
             core.debug(`go env GOPATH :${gp}:`);
             if (!fs_1.default.existsSync(gp)) {
                 // some of the hosted images have go install but not profile dir
                 core.debug(`creating ${gp}`);
                 yield io.mkdirP(gp);
             }
-            let bp = path_1.default.join(gp, 'bin');
+            const bp = path_1.default.join(gp, 'bin');
             if (!fs_1.default.existsSync(bp)) {
                 core.debug(`creating ${bp}`);
                 yield io.mkdirP(bp);
@@ -63703,18 +63701,21 @@ exports.supportedPackageManagers = {
 /***/ }),
 
 /***/ 4300:
-/***/ ((__unused_webpack_module, exports, __nccwpck_require__) => {
+/***/ (function(__unused_webpack_module, exports, __nccwpck_require__) {
 
 "use strict";
 
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
 Object.defineProperty(exports, "__esModule", ({ value: true }));
 exports.getArch = exports.getPlatform = void 0;
-const os = __nccwpck_require__(2037);
+const os_1 = __importDefault(__nccwpck_require__(2037));
 function getPlatform() {
     // darwin and linux match already
     // freebsd not supported yet but future proofed.
     // 'aix', 'darwin', 'freebsd', 'linux', 'openbsd', 'sunos', and 'win32'
-    let plat = os.platform();
+    let plat = os_1.default.platform();
     // wants 'darwin', 'freebsd', 'linux', 'windows'
     if (plat === 'win32') {
         plat = 'windows';

docs/contributors.md

@@ -52,7 +52,7 @@ Pull requests are the easiest way to contribute changes to git repos at GitHub.
 
 - Please check that no one else has already created a pull request with these changes
 - Use a "feature branch" for your changes. That separates the changes in the pull request from your other changes and makes it easy to edit/amend commits in the pull request
--  **Run `pre-checkin` script to format, build and test changes**
+-  **Run `pre-checkin` script to format, lint, build and test changes**
 - Make sure your changes are well formatted and that all tests are passing
 - If your pull request is connected to an open issue, please, leave a link to this issue in the `Related issue:` section
 - If you later need to add new commits to the pull request, you can simply commit the changes to the local branch and then push them. The pull request gets automatically updated
@@ -61,6 +61,7 @@ Pull requests are the easiest way to contribute changes to git repos at GitHub.
 
 - To implement new features or fix bugs, you need to make changes to the `.ts` files, which are located in the `src` folder
 - To comply with the code style, **you need to run the `format` script**
+- To lint the code, **you need to run the `lint:fix` script**
 - To transpile source code to `javascript` we use [NCC](https://github.com/vercel/ncc). **It is very important to run the `build` script after making changes**, otherwise your changes will not get into the final `javascript` build
 - You can also start formatting, building code, and testing with a single `pre-checkin` command
 

package.json

@@ -6,11 +6,12 @@
   "main": "lib/setup-go.js",
   "scripts": {
     "build": "tsc && ncc build -o dist/setup src/setup-go.ts && ncc build -o dist/cache-save src/cache-save.ts",
-    "format": "prettier --write **/*.ts",
+    "format": "prettier --no-error-on-unmatched-pattern --config ./.prettierrc.js --write **/*.{ts,yml,yaml}",
-    "format-check": "prettier --check **/*.ts",
+    "format-check": "prettier --no-error-on-unmatched-pattern --config ./.prettierrc.js --check **/*.{ts,yml,yaml}",
-    "lint": "echo \"Fake command that does nothing. It is used in reusable workflows\"",
+    "lint": "eslint --config ./.eslintrc.js **/*.ts",
+    "lint:fix": "eslint --config ./.eslintrc.js **/*.ts --fix",
     "test": "jest --coverage",
-    "pre-checkin": "npm run format && npm run build && npm test"
+    "pre-checkin": "npm run format && npm run lint:fix && npm run build && npm test"
   },
   "repository": {
     "type": "git",
@@ -37,11 +38,16 @@
     "@types/jest": "^27.0.2",
     "@types/node": "^16.11.25",
     "@types/semver": "^6.0.0",
+    "@typescript-eslint/eslint-plugin": "^5.54.0",
+    "@typescript-eslint/parser": "^5.54.0",
     "@vercel/ncc": "^0.33.4",
+    "eslint": "^8.35.0",
+    "eslint-config-prettier": "^8.6.0",
+    "eslint-plugin-jest": "^27.2.1",
     "jest": "^27.2.5",
     "jest-circus": "^27.2.5",
     "nock": "^10.0.6",
-    "prettier": "^1.17.1",
+    "prettier": "^2.8.4",
     "ts-jest": "^27.0.5",
     "typescript": "^4.3.3"
   }

src/cache-restore.ts

@@ -48,7 +48,7 @@ export const restoreCache = async (
 };
 
 const findDependencyFile = (packageManager: PackageManagerInfo) => {
-  let dependencyFile = packageManager.dependencyFilePattern;
+  const dependencyFile = packageManager.dependencyFilePattern;
   const workspace = process.env.GITHUB_WORKSPACE!;
   const rootContent = fs.readdirSync(workspace);
 

src/cache-utils.ts

@@ -35,7 +35,7 @@ export const getCacheDirectoryPath = async (
   packageManagerInfo: PackageManagerInfo
 ) => {
   const pathList = await Promise.all(
-    packageManagerInfo.cacheFolderCommandList.map(command =>
+    packageManagerInfo.cacheFolderCommandList.map(async command =>
       getCommandOutput(command)
     )
   );

src/installer.ts

@@ -37,7 +37,7 @@ export async function getGo(
   arch = os.arch()
 ) {
   let manifest: tc.IToolRelease[] | undefined;
-  let osPlat: string = os.platform();
+  const osPlat: string = os.platform();
 
   if (
     versionSpec === StableReleaseAlias.Stable ||
@@ -83,8 +83,7 @@ export async function getGo(
   }
 
   // check cache
-  let toolPath: string;
+  const toolPath = tc.find('go', versionSpec, arch);
-  toolPath = tc.find('go', versionSpec, arch);
   // If not found in cache, download
   if (toolPath) {
     core.info(`Found in cache @ ${toolPath}`);
@@ -246,13 +245,12 @@ async function getInfoFromDist(
   versionSpec: string,
   arch: string
 ): Promise<IGoVersionInfo | null> {
-  let version: IGoVersion | undefined;
+  const version: IGoVersion | undefined = await findMatch(versionSpec, arch);
-  version = await findMatch(versionSpec, arch);
   if (!version) {
     return null;
   }
 
-  let downloadUrl: string = `https://storage.googleapis.com/golang/${version.files[0].filename}`;
+  const downloadUrl = `https://storage.googleapis.com/golang/${version.files[0].filename}`;
 
   return <IGoVersionInfo>{
     type: 'dist',
@@ -282,8 +280,8 @@ export async function findMatch(
 
   let goFile: IGoVersionFile | undefined;
   for (let i = 0; i < candidates.length; i++) {
-    let candidate: IGoVersion = candidates[i];
+    const candidate: IGoVersion = candidates[i];
-    let version = makeSemver(candidate.version);
+    const version = makeSemver(candidate.version);
 
     core.debug(`check ${version} satisfies ${versionSpec}`);
     if (semver.satisfies(version, versionSpec)) {
@@ -331,9 +329,9 @@ export async function getVersionsDist(
 export function makeSemver(version: string): string {
   version = version.replace('go', '');
   version = version.replace('beta', '-beta.').replace('rc', '-rc.');
-  let parts = version.split('-');
+  const parts = version.split('-');
 
-  let semVersion = semver.coerce(parts[0])?.version;
+  const semVersion = semver.coerce(parts[0])?.version;
   if (!semVersion) {
     throw new Error(
       `The version: ${version} can't be changed to SemVer notation`
@@ -369,9 +367,9 @@ export function parseGoVersionFile(versionFilePath: string): string {
 }
 
 async function resolveStableVersionDist(versionSpec: string, arch: string) {
-  let archFilter = sys.getArch(arch);
+  const archFilter = sys.getArch(arch);
-  let platFilter = sys.getPlatform();
+  const platFilter = sys.getPlatform();
-  const dlUrl: string = 'https://golang.org/dl/?mode=json&include=all';
+  const dlUrl = 'https://golang.org/dl/?mode=json&include=all';
   const candidates: IGoVersion[] | null = await module.exports.getVersionsDist(
     dlUrl
   );

src/main.ts

@@ -27,8 +27,8 @@ export async function run() {
     }
 
     if (versionSpec) {
-      let token = core.getInput('token');
+      const token = core.getInput('token');
-      let auth = !token ? undefined : `token ${token}`;
+      const auth = !token ? undefined : `token ${token}`;
 
       const checkLatest = core.getBooleanInput('check-latest');
 
@@ -51,13 +51,13 @@ export async function run() {
         core.exportVariable('GOROOT', installDir);
       }
 
-      let added = await addBinToPath();
+      const added = await addBinToPath();
       core.debug(`add bin ${added}`);
       core.info(`Successfully set up Go version ${versionSpec}`);
     }
 
-    let goPath = await io.which('go');
+    const goPath = await io.which('go');
-    let goVersion = (cp.execSync(`${goPath} version`) || '').toString();
+    const goVersion = (cp.execSync(`${goPath} version`) || '').toString();
 
     if (cache && isCacheFeatureAvailable()) {
       const packageManager = 'default';
@@ -79,7 +79,7 @@ export async function run() {
     core.setOutput('go-version', parseGoVersion(goVersion));
 
     core.startGroup('go env');
-    let goEnv = (cp.execSync(`${goPath} env`) || '').toString();
+    const goEnv = (cp.execSync(`${goPath} env`) || '').toString();
     core.info(goEnv);
     core.endGroup();
   } catch (error) {
@@ -89,16 +89,16 @@ export async function run() {
 
 export async function addBinToPath(): Promise<boolean> {
   let added = false;
-  let g = await io.which('go');
+  const g = await io.which('go');
   core.debug(`which go :${g}:`);
   if (!g) {
     core.debug('go not in the path');
     return added;
   }
 
-  let buf = cp.execSync('go env GOPATH');
+  const buf = cp.execSync('go env GOPATH');
   if (buf.length > 1) {
-    let gp = buf.toString().trim();
+    const gp = buf.toString().trim();
     core.debug(`go env GOPATH :${gp}:`);
     if (!fs.existsSync(gp)) {
       // some of the hosted images have go install but not profile dir
@@ -106,7 +106,7 @@ export async function addBinToPath(): Promise<boolean> {
       await io.mkdirP(gp);
     }
 
-    let bp = path.join(gp, 'bin');
+    const bp = path.join(gp, 'bin');
     if (!fs.existsSync(bp)) {
       core.debug(`creating ${bp}`);
       await io.mkdirP(bp);

src/system.ts

@@ -1,4 +1,4 @@
-const os = require('os');
+import os from 'os';
 
 export function getPlatform(): string {
   // darwin and linux match already

tsconfig.json

@@ -46,6 +46,7 @@
     // "types": [],                           /* Type declaration files to be included in compilation. */
     // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
     "esModuleInterop": true,                  /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
+    "resolveJsonModule": true,                /* Allows importing modules with a '.json' extension, which is a common practice in node projects. */
     "sourceMap": true,
     // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
     // "allowUmdGlobalAccess": true,          /* Allow accessing UMD globals from modules. */