refactor: add eslint rules to enforce import order

We want to check for cycle-dependencies to prevent bugs that are not
detected by TypeScript type checks. We want also to tag type-only
profiles with "import type" annotation to gain visibility.

.eslintrc.js

@@ -1,17 +1,42 @@
 module.exports = {
   root: true,
   parser: '@typescript-eslint/parser',
-  plugins: ['@typescript-eslint'],
+  plugins: ['@typescript-eslint', 'import', 'prettier'],
   extends: [
     'eslint:recommended',
     'plugin:@typescript-eslint/recommended',
     'plugin:node/recommended',
-    'prettier',
   ],
   settings: {
     node: {
       tryExtensions: ['.js', '.json', '.ts', '.d.ts'],
     },
+    'import/extensions': ['.js', '.json', '.ts', '.d.ts'],
+    'import/external-module-folders': ['node_modules', 'node_modules/@types'],
+    'import/parsers': {
+      '@typescript-eslint/parser': ['.ts'],
+    },
+    'import/resolver': {
+      node: {
+        extensions: ['.js', '.json', '.ts', '.d.ts'],
+      },
+    },
+  },
+  rules: {
+    '@typescript-eslint/consistent-type-imports': ['error', { prefer: 'type-imports' }],
+    'import/order': [
+      'error',
+      {
+        groups: ['builtin', 'external', 'internal', 'parent', 'sibling', 'index', 'object'],
+        'newlines-between': 'always',
+        alphabetize: {
+          order: 'asc',
+          caseInsensitive: true,
+        },
+      },
+    ],
+    'import/no-cycle': ['error'],
+    'prettier/prettier': 'error',
   },
   overrides: [
     {

package.json

@@ -69,8 +69,8 @@
     "tapable": "^2.0.0"
   },
   "peerDependencies": {
-    "webpack": "^5.11.0",
-    "typescript": ">3.6.0"
+    "typescript": ">3.6.0",
+    "webpack": "^5.11.0"
   },
   "devDependencies": {
     "@commitlint/config-conventional": "^13.1.0",
@@ -89,19 +89,20 @@
     "@types/node": "^16.4.13",
     "@types/rimraf": "^3.0.1",
     "@types/semver": "^7.3.8",
-    "@typescript-eslint/eslint-plugin": "^4.29.0",
-    "@typescript-eslint/parser": "^4.29.0",
+    "@typescript-eslint/eslint-plugin": "^5.1.0",
+    "@typescript-eslint/parser": "^5.1.0",
     "commitlint": "^13.1.0",
     "cross-env": "^7.0.3",
     "eslint": "^7.32.0",
-    "eslint-config-prettier": "^8.3.0",
+    "eslint-plugin-import": "^2.25.2",
     "eslint-plugin-node": "^11.1.0",
-    "eslint-plugin-prettier": "^3.4.0",
+    "eslint-plugin-prettier": "^4.0.0",
     "git-cz": "^4.7.6",
     "husky": "^7.0.0",
     "jest": "^27.0.6",
     "jest-circus": "^27.0.6",
     "jest-environment-node": "^27.0.6",
+    "json-schema": "^0.3.0",
     "karton": "^0.4.1",
     "lint-staged": "^11.1.2",
     "mock-fs": "^5.0.0",

src/ForkTsCheckerWebpackPlugin.ts

@@ -1,24 +1,24 @@
-import webpack from 'webpack';
+import { cosmiconfigSync } from 'cosmiconfig';
+import merge from 'deepmerge';
+import type { JSONSchema7 } from 'json-schema';
 import { validate } from 'schema-utils';
+import type webpack from 'webpack';
 // type only dependency
 // eslint-disable-next-line node/no-extraneous-import
-import type { JSONSchema7 } from 'json-schema';
-import { cosmiconfigSync } from 'cosmiconfig';
-import merge from 'deepmerge';
-import schema from './ForkTsCheckerWebpackPluginOptions.json';
-import { ForkTsCheckerWebpackPluginOptions } from './ForkTsCheckerWebpackPluginOptions';
+
 import { createForkTsCheckerWebpackPluginConfiguration } from './ForkTsCheckerWebpackPluginConfiguration';
+import type { ForkTsCheckerWebpackPluginOptions } from './ForkTsCheckerWebpackPluginOptions';
+import schema from './ForkTsCheckerWebpackPluginOptions.json';
 import { createForkTsCheckerWebpackPluginState } from './ForkTsCheckerWebpackPluginState';
-import { assertTypeScriptSupport } from './typescript-reporter/TypeScriptSupport';
-import { createTypeScriptReporterRpcClient } from './typescript-reporter/reporter/TypeScriptReporterRpcClient';
-import { tapStartToConnectAndRunReporter } from './hooks/tapStartToConnectAndRunReporter';
-import { tapStopToDisconnectReporter } from './hooks/tapStopToDisconnectReporter';
-import { tapAfterCompileToAddDependencies } from './hooks/tapAfterCompileToAddDependencies';
-import { tapErrorToLogMessage } from './hooks/tapErrorToLogMessage';
 import { getForkTsCheckerWebpackPluginHooks } from './hooks/pluginHooks';
+import { dependenciesPool, issuesPool } from './hooks/pluginPools';
+import { tapAfterCompileToAddDependencies } from './hooks/tapAfterCompileToAddDependencies';
 import { tapAfterEnvironmentToPatchWatching } from './hooks/tapAfterEnvironmentToPatchWatching';
-import { createPool, Pool } from './utils/async/pool';
-import os from 'os';
+import { tapErrorToLogMessage } from './hooks/tapErrorToLogMessage';
+import { tapStartToConnectAndRunReporter } from './hooks/tapStartToConnectAndRunReporter';
+import { tapStopToDisconnectReporter } from './hooks/tapStopToDisconnectReporter';
+import { createTypeScriptReporterRpcClient } from './typescript-reporter/reporter/TypeScriptReporterRpcClient';
+import { assertTypeScriptSupport } from './typescript-reporter/TypeScriptSupport';
 
 class ForkTsCheckerWebpackPlugin {
   /**
@@ -28,16 +28,13 @@ class ForkTsCheckerWebpackPlugin {
   /**
    * Default pools for the plugin concurrency limit
    */
-  static readonly issuesPool: Pool = createPool(Math.max(1, os.cpus().length));
-  static readonly dependenciesPool: Pool = createPool(Math.max(1, os.cpus().length));
+  static readonly issuesPool = issuesPool;
+  static readonly dependenciesPool = dependenciesPool;
 
   /**
    * @deprecated Use ForkTsCheckerWebpackPlugin.issuesPool instead
    */
-  static get pool(): Pool {
-    // for backward compatibility
-    return ForkTsCheckerWebpackPlugin.issuesPool;
-  }
+  static readonly pool = issuesPool;
 
   private readonly options: ForkTsCheckerWebpackPluginOptions;
 

src/ForkTsCheckerWebpackPluginConfiguration.ts

@@ -1,12 +1,14 @@
-import webpack from 'webpack';
-import { ForkTsCheckerWebpackPluginOptions } from './ForkTsCheckerWebpackPluginOptions';
-import { createIssueConfiguration, IssueConfiguration } from './issue/IssueConfiguration';
-import { createFormatterConfiguration, FormatterConfiguration } from './formatter';
-import {
-  createTypeScriptReporterConfiguration,
-  TypeScriptReporterConfiguration,
-} from './typescript-reporter/TypeScriptReporterConfiguration';
-import { createLoggerConfiguration, LoggerConfiguration } from './logger/LoggerConfiguration';
+import type webpack from 'webpack';
+
+import type { ForkTsCheckerWebpackPluginOptions } from './ForkTsCheckerWebpackPluginOptions';
+import type { FormatterConfiguration } from './formatter';
+import { createFormatterConfiguration } from './formatter';
+import type { IssueConfiguration } from './issue/IssueConfiguration';
+import { createIssueConfiguration } from './issue/IssueConfiguration';
+import type { LoggerConfiguration } from './logger/LoggerConfiguration';
+import { createLoggerConfiguration } from './logger/LoggerConfiguration';
+import type { TypeScriptReporterConfiguration } from './typescript-reporter/TypeScriptReporterConfiguration';
+import { createTypeScriptReporterConfiguration } from './typescript-reporter/TypeScriptReporterConfiguration';
 
 interface ForkTsCheckerWebpackPluginConfiguration {
   async: boolean;

src/ForkTsCheckerWebpackPluginOptions.ts

@@ -1,7 +1,7 @@
-import { TypeScriptReporterOptions } from './typescript-reporter/TypeScriptReporterOptions';
-import { IssueOptions } from './issue/IssueOptions';
-import { FormatterOptions } from './formatter';
-import LoggerOptions from './logger/LoggerOptions';
+import type { FormatterOptions } from './formatter';
+import type { IssueOptions } from './issue/IssueOptions';
+import type LoggerOptions from './logger/LoggerOptions';
+import type { TypeScriptReporterOptions } from './typescript-reporter/TypeScriptReporterOptions';
 
 interface ForkTsCheckerWebpackPluginOptions {
   async?: boolean;

src/ForkTsCheckerWebpackPluginState.ts

@@ -1,6 +1,7 @@
-import { FullTap } from 'tapable';
-import { FilesMatch, Report } from './reporter';
-import { Issue } from './issue';
+import type { FullTap } from 'tapable';
+
+import type { Issue } from './issue';
+import type { FilesMatch, Report } from './reporter';
 
 interface ForkTsCheckerWebpackPluginState {
   issuesReportPromise: Promise<Report | undefined>;

src/formatter/BasicFormatter.ts

@@ -1,5 +1,6 @@
 import chalk from 'chalk';
-import { Formatter } from './Formatter';
+
+import type { Formatter } from './Formatter';
 
 function createBasicFormatter(): Formatter {
   return function basicFormatter(issue) {

src/formatter/CodeFrameFormatter.ts

@@ -1,8 +1,10 @@
 import os from 'os';
-import fs from 'fs-extra';
+
 import { codeFrameColumns } from '@babel/code-frame';
-import { Formatter } from './Formatter';
+import fs from 'fs-extra';
+
 import { createBasicFormatter } from './BasicFormatter';
+import type { Formatter } from './Formatter';
 import { BabelCodeFrameOptions } from './types/babel__code-frame';
 
 function createCodeFrameFormatter(options?: BabelCodeFrameOptions): Formatter {

src/formatter/Formatter.ts

@@ -1,4 +1,4 @@
-import { Issue } from '../issue';
+import type { Issue } from '../issue';
 
 type Formatter = (issue: Issue) => string;
 

src/formatter/FormatterConfiguration.ts

@@ -1,7 +1,7 @@
-import { CodeframeFormatterOptions, FormatterOptions } from './FormatterOptions';
-import { Formatter } from './Formatter';
 import { createBasicFormatter } from './BasicFormatter';
 import { createCodeFrameFormatter } from './CodeFrameFormatter';
+import type { Formatter } from './Formatter';
+import type { CodeframeFormatterOptions, FormatterOptions } from './FormatterOptions';
 
 type FormatterConfiguration = Formatter;
 

src/formatter/FormatterOptions.ts

@@ -1,5 +1,5 @@
-import { Formatter } from './Formatter';
-import { BabelCodeFrameOptions } from './types/babel__code-frame';
+import type { Formatter } from './Formatter';
+import type { BabelCodeFrameOptions } from './types/babel__code-frame';
 
 type FormatterType = 'basic' | 'codeframe';
 

src/formatter/WebpackFormatter.ts

@@ -1,9 +1,12 @@
 import os from 'os';
+
 import chalk from 'chalk';
-import { Formatter } from './Formatter';
+
 import { formatIssueLocation } from '../issue';
 import { relativeToContext } from '../utils/path/relativeToContext';
 
+import type { Formatter } from './Formatter';
+
 function createWebpackFormatter(formatter: Formatter): Formatter {
   // mimics webpack error formatter
   return function webpackFormatter(issue) {

src/hooks/interceptDoneToGetWebpackDevServerTap.ts

@@ -1,6 +1,7 @@
-import webpack from 'webpack';
-import { ForkTsCheckerWebpackPluginConfiguration } from '../ForkTsCheckerWebpackPluginConfiguration';
-import { ForkTsCheckerWebpackPluginState } from '../ForkTsCheckerWebpackPluginState';
+import type webpack from 'webpack';
+
+import type { ForkTsCheckerWebpackPluginConfiguration } from '../ForkTsCheckerWebpackPluginConfiguration';
+import type { ForkTsCheckerWebpackPluginState } from '../ForkTsCheckerWebpackPluginState';
 
 function interceptDoneToGetWebpackDevServerTap(
   compiler: webpack.Compiler,

src/hooks/pluginHooks.ts

@@ -1,7 +1,8 @@
-import * as webpack from 'webpack';
 import { SyncHook, SyncWaterfallHook, AsyncSeriesWaterfallHook } from 'tapable';
-import { FilesChange } from '../reporter';
-import { Issue } from '../issue';
+import type * as webpack from 'webpack';
+
+import type { Issue } from '../issue';
+import type { FilesChange } from '../reporter';
 
 const compilerHookMap = new WeakMap<
   webpack.Compiler | webpack.MultiCompiler,

src/hooks/pluginPools.ts

@@ -0,0 +1,9 @@
+import * as os from 'os';
+
+import type { Pool } from '../utils/async/pool';
+import { createPool } from '../utils/async/pool';
+
+const issuesPool: Pool = createPool(Math.max(1, os.cpus().length));
+const dependenciesPool: Pool = createPool(Math.max(1, os.cpus().length));
+
+export { issuesPool, dependenciesPool };

src/hooks/tapAfterCompileToAddDependencies.ts

@@ -1,6 +1,7 @@
-import webpack from 'webpack';
-import { ForkTsCheckerWebpackPluginConfiguration } from '../ForkTsCheckerWebpackPluginConfiguration';
-import { ForkTsCheckerWebpackPluginState } from '../ForkTsCheckerWebpackPluginState';
+import type webpack from 'webpack';
+
+import type { ForkTsCheckerWebpackPluginConfiguration } from '../ForkTsCheckerWebpackPluginConfiguration';
+import type { ForkTsCheckerWebpackPluginState } from '../ForkTsCheckerWebpackPluginState';
 
 function tapAfterCompileToAddDependencies(
   compiler: webpack.Compiler,

src/hooks/tapAfterCompileToGetIssues.ts

@@ -1,9 +1,11 @@
-import webpack from 'webpack';
-import { ForkTsCheckerWebpackPluginConfiguration } from '../ForkTsCheckerWebpackPluginConfiguration';
-import { ForkTsCheckerWebpackPluginState } from '../ForkTsCheckerWebpackPluginState';
-import { getForkTsCheckerWebpackPluginHooks } from './pluginHooks';
+import type webpack from 'webpack';
+
+import type { ForkTsCheckerWebpackPluginConfiguration } from '../ForkTsCheckerWebpackPluginConfiguration';
+import type { ForkTsCheckerWebpackPluginState } from '../ForkTsCheckerWebpackPluginState';
+import type { Issue } from '../issue';
 import { IssueWebpackError } from '../issue/IssueWebpackError';
-import { Issue } from '../issue';
+
+import { getForkTsCheckerWebpackPluginHooks } from './pluginHooks';
 
 function tapAfterCompileToGetIssues(
   compiler: webpack.Compiler,

src/hooks/tapAfterEnvironmentToPatchWatching.ts

@@ -1,7 +1,8 @@
-import webpack from 'webpack';
-import { ForkTsCheckerWebpackPluginState } from '../ForkTsCheckerWebpackPluginState';
+import type webpack from 'webpack';
+
+import type { ForkTsCheckerWebpackPluginState } from '../ForkTsCheckerWebpackPluginState';
 import { InclusiveNodeWatchFileSystem } from '../watch/InclusiveNodeWatchFileSystem';
-import { WatchFileSystem } from '../watch/WatchFileSystem';
+import type { WatchFileSystem } from '../watch/WatchFileSystem';
 
 function tapAfterEnvironmentToPatchWatching(
   compiler: webpack.Compiler,

src/hooks/tapDoneToAsyncGetIssues.ts

@@ -1,14 +1,16 @@
-import webpack from 'webpack';
 import chalk from 'chalk';
-import { ForkTsCheckerWebpackPluginConfiguration } from '../ForkTsCheckerWebpackPluginConfiguration';
-import { ForkTsCheckerWebpackPluginState } from '../ForkTsCheckerWebpackPluginState';
-import { getForkTsCheckerWebpackPluginHooks } from './pluginHooks';
+import type webpack from 'webpack';
+
+import type { ForkTsCheckerWebpackPluginConfiguration } from '../ForkTsCheckerWebpackPluginConfiguration';
+import type { ForkTsCheckerWebpackPluginState } from '../ForkTsCheckerWebpackPluginState';
 import { createWebpackFormatter } from '../formatter/WebpackFormatter';
-import { Issue } from '../issue';
+import type { Issue } from '../issue';
 import { IssueWebpackError } from '../issue/IssueWebpackError';
 import isPending from '../utils/async/isPending';
 import wait from '../utils/async/wait';
 
+import { getForkTsCheckerWebpackPluginHooks } from './pluginHooks';
+
 function tapDoneToAsyncGetIssues(
   compiler: webpack.Compiler,
   configuration: ForkTsCheckerWebpackPluginConfiguration,

src/hooks/tapErrorToLogMessage.ts

@@ -1,8 +1,10 @@
-import webpack from 'webpack';
-import { ForkTsCheckerWebpackPluginConfiguration } from '../ForkTsCheckerWebpackPluginConfiguration';
-import { getForkTsCheckerWebpackPluginHooks } from './pluginHooks';
-import { RpcIpcMessagePortClosedError } from '../rpc/rpc-ipc/error/RpcIpcMessagePortClosedError';
 import chalk from 'chalk';
+import type webpack from 'webpack';
+
+import type { ForkTsCheckerWebpackPluginConfiguration } from '../ForkTsCheckerWebpackPluginConfiguration';
+import { RpcIpcMessagePortClosedError } from '../rpc/rpc-ipc/error/RpcIpcMessagePortClosedError';
+
+import { getForkTsCheckerWebpackPluginHooks } from './pluginHooks';
 
 function tapErrorToLogMessage(
   compiler: webpack.Compiler,