fix: lint modules that are cached with webpack's filesystem cache

If webpack is setup with cache type `filesystem`, the `succeedModule`
hook is not called for cached modules and no linting is run for them.
Tap the `stillValidModule` hook to lint cached modules.

Fixes webpack-contrib#130

src/index.js

@@ -7,6 +7,8 @@ const linter = require('./linter');
 const { arrify, parseFiles, parseFoldersToGlobs } = require('./utils');
 
 /** @typedef {import('webpack').Compiler} Compiler */
+/** @typedef {import('webpack').Module} Module */
+/** @typedef {import('webpack').NormalModule} NormalModule */
 /** @typedef {import('./options').Options} Options */
 
 const ESLINT_PLUGIN = 'ESLintWebpackPlugin';
@@ -103,9 +105,16 @@ class ESLintWebpackPlugin {
       /** @type {string[]} */
       const files = [];
 
-      // @ts-ignore
       // Add the file to be linted
-      compilation.hooks.succeedModule.tap(this.key, ({ resource }) => {
+      compilation.hooks.succeedModule.tap(this.key, addFile);
+      compilation.hooks.stillValidModule.tap(this.key, addFile);
+
+      /**
+       * @param {Module} module
+       */
+      function addFile(module) {
+        const { resource } = /** @type {NormalModule} */ (module);
+
         if (resource) {
           const [file, query] = resource.split('?');
 
@@ -123,7 +132,7 @@ class ESLintWebpackPlugin {
             }
           }
         }
-      });
+      }
 
       // Lint all files added
       compilation.hooks.finishModules.tap(this.key, () => {

test/cached.test.js

@@ -0,0 +1,49 @@
+import { join } from 'path';
+
+import { removeSync } from 'fs-extra';
+
+import webpack from 'webpack';
+
+import conf from './utils/conf';
+
+describe('error (cached module)', () => {
+  const cacheLocation = join(__dirname, 'cache');
+
+  beforeEach(() => {
+    removeSync(cacheLocation);
+  });
+
+  afterAll(() => {
+    removeSync(cacheLocation);
+  });
+
+  it('should return error even if module is cached', (done) => {
+    const config = conf('error');
+    config.cache = {
+      type: 'filesystem',
+      idleTimeout: 0,
+      idleTimeoutAfterLargeChanges: 0,
+      idleTimeoutForInitialStore: 0,
+      cacheLocation,
+    };
+
+    const c1 = webpack(config);
+
+    c1.run((err1, stats1) => {
+      expect(err1).toBeNull();
+      expect(stats1.hasWarnings()).toBe(false);
+      expect(stats1.hasErrors()).toBe(true);
+
+      c1.close(() => {
+        const c2 = webpack(config);
+        c2.run((err2, stats2) => {
+          expect(err2).toBeNull();
+          expect(stats2.hasWarnings()).toBe(false);
+          expect(stats2.hasErrors()).toBe(true);
+
+          done();
+        });
+      });
+    });
+  });
+});

types/index.d.ts

@@ -33,7 +33,9 @@ declare class ESLintWebpackPlugin {
   getContext(compiler: Compiler): string;
 }
 declare namespace ESLintWebpackPlugin {
-  export { Compiler, Options };
+  export { Compiler, Module, NormalModule, Options };
 }
 type Compiler = import('webpack').Compiler;
 type Options = import('./options').Options;
+type Module = import('webpack').Module;
+type NormalModule = import('webpack').NormalModule;