[Fix] no-unused-modules: fix usage of import/extensions settings

CHANGELOG.md

@@ -5,6 +5,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This change log adheres to standards from [Keep a CHANGELOG](http://keepachangelog.com).
 
 ## [Unreleased]
+- [`no-unused-modules`]: fix usage of `import/extensions` settings ([#1560], thanks [@stekycz])
 
 ## [2.19.1] - 2019-12-08
 ### Fixed
@@ -619,6 +620,7 @@ for info on changes for earlier releases.
 
 [`memo-parser`]: ./memo-parser/README.md
 
+[#1560]: https://github.com/benmosher/eslint-plugin-import/pull/1560
 [#1551]: https://github.com/benmosher/eslint-plugin-import/pull/1551
 [#1542]: https://github.com/benmosher/eslint-plugin-import/pull/1542
 [#1521]: https://github.com/benmosher/eslint-plugin-import/pull/1521
@@ -1037,3 +1039,4 @@ for info on changes for earlier releases.
 [@christophercurrie]: https://github.com/christophercurrie
 [@randallreedjr]: https://github.com/randallreedjr
 [@Pessimistress]: https://github.com/Pessimistress
+[@stekycz]: https://github.com/stekycz

src/rules/no-unused-modules.js

@@ -5,6 +5,7 @@
  */
 
 import Exports from '../ExportMap'
+import { getFileExtensions } from 'eslint-module-utils/ignore'
 import resolve from 'eslint-module-utils/resolve'
 import docsUrl from '../docsUrl'
 import { dirname, join } from 'path'
@@ -17,18 +18,27 @@ import includes from 'array-includes'
 let listFilesToProcess
 try {
   var FileEnumerator = require('eslint/lib/cli-engine/file-enumerator').FileEnumerator
-  listFilesToProcess = function (src) {
-    var e = new FileEnumerator()
+  listFilesToProcess = function (src, extensions) {
+    var e = new FileEnumerator({
+      extensions: extensions,
+    })
     return Array.from(e.iterateFiles(src), ({ filePath, ignored }) => ({
       ignored,
       filename: filePath,
     }))
   }
 } catch (e1) {
+  let originalListFilesToProcess
   try {
-    listFilesToProcess = require('eslint/lib/util/glob-utils').listFilesToProcess
+    originalListFilesToProcess = require('eslint/lib/util/glob-utils').listFilesToProcess
   } catch (e2) {
-    listFilesToProcess = require('eslint/lib/util/glob-util').listFilesToProcess
+    originalListFilesToProcess = require('eslint/lib/util/glob-util').listFilesToProcess
+  }
+  // Prevent passing invalid options (extensions array) to old versions of the function.
+  // https://github.com/eslint/eslint/blob/v5.16.0/lib/util/glob-utils.js#L178-L280
+  // https://github.com/eslint/eslint/blob/v5.2.0/lib/util/glob-util.js#L174-L269
+  listFilesToProcess = function (src) {
+    return originalListFilesToProcess(src)
   }
 }
 
@@ -59,12 +69,14 @@ const isNodeModule = path => {
  *
  * return all files matching src pattern, which are not matching the ignoreExports pattern
  */
-const resolveFiles = (src, ignoreExports) => {
+const resolveFiles = (src, ignoreExports, context) => {
+  const extensions = Array.from(getFileExtensions(context.settings))
+
   const srcFiles = new Set()
-  const srcFileList = listFilesToProcess(src)
+  const srcFileList = listFilesToProcess(src, extensions)
 
   // prepare list of ignored files
-  const ignoredFilesList =  listFilesToProcess(ignoreExports)
+  const ignoredFilesList =  listFilesToProcess(ignoreExports, extensions)
   ignoredFilesList.forEach(({ filename }) => ignoredFiles.add(filename))
 
   // prepare list of source files, don't consider files from node_modules
@@ -201,7 +213,7 @@ const getSrc = src => {
  */
 let srcFiles
 const doPreparation = (src, ignoreExports, context) => {
-  srcFiles = resolveFiles(getSrc(src), ignoreExports)
+  srcFiles = resolveFiles(getSrc(src), ignoreExports, context)
   prepareImportsAndExports(srcFiles, context)
   determineUsage()
   preparationDone = true
@@ -389,7 +401,7 @@ module.exports = {
 
       // make sure file to be linted is included in source files
       if (!srcFiles.has(file)) {
-        srcFiles = resolveFiles(getSrc(src), ignoreExports)
+        srcFiles = resolveFiles(getSrc(src), ignoreExports, context)
         if (!srcFiles.has(file)) {
           filesOutsideSrc.add(file)
           return

tests/files/no-unused-modules/typescript/file-ts-a.ts

@@ -0,0 +1,3 @@
+import {b} from './file-ts-b';
+
+export const a = b + 1;

tests/files/no-unused-modules/typescript/file-ts-b.ts

@@ -0,0 +1 @@
+export const b = 2;

tests/src/rules/no-unused-modules.typescript.js

@@ -0,0 +1,42 @@
+import { test, testFilePath } from '../utils'
+import typescriptConfig from '../../../config/typescript'
+
+import { RuleTester } from 'eslint'
+
+// We need to clear the cache to reinitialize the rule for Typescript only
+delete require.cache[require.resolve('rules/no-unused-modules')]
+
+const ruleTester = new RuleTester(typescriptConfig)
+    , rule = require('rules/no-unused-modules')
+
+const error = message => ({ ruleId: 'no-unused-modules', message })
+
+const unusedExportsTypescriptOptions = [{
+  unusedExports: true,
+  src: [testFilePath('./no-unused-modules/typescript')],
+  ignoreExports: undefined,
+}]
+
+describe('correctly work with Typescript only files', () => {
+  ruleTester.run('no-unused-modules', rule, {
+    valid: [
+      test({
+        options: unusedExportsTypescriptOptions,
+        code: 'import a from "file-a";',
+        parser: require.resolve('@typescript-eslint/parser'),
+        filename: testFilePath('./no-unused-modules/typescript/file-ts-a.ts'),
+      }),
+    ],
+    invalid: [
+      test({
+        options: unusedExportsTypescriptOptions,
+        code: `export const b = 2;`,
+        parser: require.resolve('@typescript-eslint/parser'),
+        filename: testFilePath('./no-unused-modules/typescript/file-ts-b.ts'),
+        errors: [
+          error(`exported declaration 'b' not used within other modules`),
+        ],
+      }),
+    ],
+  })
+})