[New] no-unused-modules: support dynamic imports

All occurences of `import('...')` are treated as namespace imports
(`import * as X from '...'`)

See #1660, #2212.

Co-authored-by: Max Komarychev <maxkomarychev@gmail.com>
Co-authored-by: Filipp Riabchun <filipp.riabchun@jetbrains.com>
Co-authored-by: 薛定谔的猫 <weiran.zsd@outlook.com>

CHANGELOG.md

@@ -10,6 +10,7 @@ This change log adheres to standards from [Keep a CHANGELOG](http://keepachangel
 - [`no-unresolved`]: add `caseSensitiveStrict` option ([#1262], thanks [@sergei-startsev])
 - [`no-unused-modules`]: add eslint v8 support ([#2194], thanks [@coderaiser])
 - [`no-restricted-paths`]: add/restore glob pattern support ([#2219], thanks [@stropho])
+- [`no-unused-modules`]: support dynamic imports ([#1660], [#2212], thanks [@maxkomarychev], [@aladdin-add], [@Hypnosphi])
 
 ## [2.24.2] - 2021-08-24
 
@@ -906,6 +907,7 @@ for info on changes for earlier releases.
 [`memo-parser`]: ./memo-parser/README.md
 
 [#2219]: https://github.com/import-js/eslint-plugin-import/pull/2219
+[#2212]: https://github.com/import-js/eslint-plugin-import/pull/2212
 [#2196]: https://github.com/import-js/eslint-plugin-import/pull/2196
 [#2194]: https://github.com/import-js/eslint-plugin-import/pull/2194
 [#2184]: https://github.com/import-js/eslint-plugin-import/pull/2184
@@ -983,6 +985,7 @@ for info on changes for earlier releases.
 [#1676]: https://github.com/import-js/eslint-plugin-import/pull/1676
 [#1666]: https://github.com/import-js/eslint-plugin-import/pull/1666
 [#1664]: https://github.com/import-js/eslint-plugin-import/pull/1664
+[#1660]: https://github.com/import-js/eslint-plugin-import/pull/1660
 [#1658]: https://github.com/import-js/eslint-plugin-import/pull/1658
 [#1651]: https://github.com/import-js/eslint-plugin-import/pull/1651
 [#1626]: https://github.com/import-js/eslint-plugin-import/pull/1626
@@ -1487,6 +1490,7 @@ for info on changes for earlier releases.
 [@MatthiasKunnen]: https://github.com/MatthiasKunnen
 [@mattijsbliek]: https://github.com/mattijsbliek
 [@Maxim-Mazurok]: https://github.com/Maxim-Mazurok
+[@maxkomarychev]: https://github.com/maxkomarychev
 [@maxmalov]: https://github.com/maxmalov
 [@MikeyBeLike]: https://github.com/MikeyBeLike
 [@mplewis]: https://github.com/mplewis

docs/rules/no-unused-modules.md

@@ -3,8 +3,8 @@
 Reports:
   - modules without any exports
   - individual exports not being statically `import`ed or `require`ed from other modules in the same project
+  - dynamic imports are supported if argument is a literal string
 
-Note: dynamic imports are currently not supported.
 
 ## Rule Details
 

src/ExportMap.js

@@ -7,6 +7,7 @@ import debug from 'debug';
 import { SourceCode } from 'eslint';
 
 import parse from 'eslint-module-utils/parse';
+import visit from 'eslint-module-utils/visit';
 import resolve from 'eslint-module-utils/resolve';
 import isIgnored, { hasValidExtension } from 'eslint-module-utils/ignore';
 
@@ -354,15 +355,57 @@ ExportMap.parse = function (path, content, context) {
   const isEsModuleInteropTrue = isEsModuleInterop();
 
   let ast;
+  let visitorKeys;
   try {
-    ast = parse(path, content, context);
+    const result = parse(path, content, context);
+    ast = result.ast;
+    visitorKeys = result.visitorKeys;
   } catch (err) {
-    log('parse error:', path, err);
     m.errors.push(err);
     return m; // can't continue
   }
 
-  if (!unambiguous.isModule(ast)) return null;
+  m.visitorKeys = visitorKeys;
+
+  let hasDynamicImports = false;
+
+  function processDynamicImport(source) {
+    hasDynamicImports = true;
+    if (source.type !== 'Literal') {
+      return null;
+    }
+    const p = remotePath(source.value);
+    if (p == null) {
+      return null;
+    }
+    const importedSpecifiers = new Set();
+    importedSpecifiers.add('ImportNamespaceSpecifier');
+    const getter = thunkFor(p, context);
+    m.imports.set(p, {
+      getter,
+      declarations: new Set([{
+        source: {
+        // capturing actual node reference holds full AST in memory!
+          value: source.value,
+          loc: source.loc,
+        },
+        importedSpecifiers,
+      }]),
+    });
+  }
+
+  visit(ast, visitorKeys, {
+    ImportExpression(node) {
+      processDynamicImport(node.source);
+    },
+    CallExpression(node) {
+      if (node.callee.type === 'Import') {
+        processDynamicImport(node.arguments[0]);
+      }
+    },
+  });
+
+  if (!unambiguous.isModule(ast) && !hasDynamicImports) return null;
 
   const docstyle = (context.settings && context.settings['import/docstyle']) || ['jsdoc'];
   const docStyleParsers = {};

src/rules/no-unused-modules.js

@@ -7,6 +7,7 @@
 import Exports, { recursivePatternCapture } from '../ExportMap';
 import { getFileExtensions } from 'eslint-module-utils/ignore';
 import resolve from 'eslint-module-utils/resolve';
+import visit from 'eslint-module-utils/visit';
 import docsUrl from '../docsUrl';
 import { dirname, join } from 'path';
 import readPkgUp from 'read-pkg-up';
@@ -154,6 +155,8 @@ const importList = new Map();
  */
 const exportList = new Map();
 
+const visitorKeyMap = new Map();
+
 const ignoredFiles = new Set();
 const filesOutsideSrc = new Set();
 
@@ -193,8 +196,15 @@ const prepareImportsAndExports = (srcFiles, context) => {
     const imports = new Map();
     const currentExports = Exports.get(file, context);
     if (currentExports) {
-      const { dependencies, reexports, imports: localImportList, namespace  } = currentExports;
-
+      const {
+        dependencies,
+        reexports,
+        imports: localImportList,
+        namespace,
+        visitorKeys,
+      } = currentExports;
+
+      visitorKeyMap.set(file, visitorKeys);
       // dependencies === export * from
       const currentExportAll = new Set();
       dependencies.forEach(getDependency => {
@@ -675,6 +685,28 @@ module.exports = {
         });
       });
 
+      function processDynamicImport(source) {
+        if (source.type !== 'Literal') {
+          return null;
+        }
+        const p = resolve(source.value, context);
+        if (p == null) {
+          return null;
+        }
+        newNamespaceImports.add(p);
+      }
+
+      visit(node, visitorKeyMap.get(file), {
+        ImportExpression(child) {
+          processDynamicImport(child.source);
+        },
+        CallExpression(child) {
+          if (child.callee.type === 'Import') {
+            processDynamicImport(child.arguments[0]);
+          }
+        },
+      });
+
       node.body.forEach(astNode => {
         let resolvedPath;
 

tests/files/no-unused-modules/dynamic-import-js-2.js

@@ -0,0 +1,13 @@
+const importPath = './exports-for-dynamic-js';
+class A {
+    method() {
+        const c = import(importPath)
+    }
+}
+
+
+class B {
+    method() {
+        const c = import('i-do-not-exist')
+    }
+}

tests/files/no-unused-modules/dynamic-import-js.js

@@ -0,0 +1,5 @@
+class A {
+    method() {
+        const c = import('./exports-for-dynamic-js')
+    }
+}

tests/files/no-unused-modules/exports-for-dynamic-js-2.js

@@ -0,0 +1,5 @@
+export const a = 10;
+export const b = 20;
+export const c = 30;
+const d = 40;
+export default d;

tests/files/no-unused-modules/exports-for-dynamic-js.js

@@ -0,0 +1,5 @@
+export const a = 10
+export const b = 20
+export const c = 30
+const d = 40
+export default d

tests/files/no-unused-modules/typescript/dynamic-import-ts.ts

@@ -0,0 +1,6 @@
+class A {
+    method() {
+        const c = import('./exports-for-dynamic-ts')
+    }
+}
+

tests/files/no-unused-modules/typescript/exports-for-dynamic-ts.ts

@@ -0,0 +1,5 @@
+export const ts_a = 10
+export const ts_b = 20
+export const ts_c = 30
+const ts_d = 40
+export default ts_d

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

@@ -112,41 +112,49 @@ ruleTester.run('no-unused-modules', rule, {
       options: unusedExportsOptions,
       code: 'import { o2 } from "./file-o";export default () => 12',
       filename: testFilePath('./no-unused-modules/file-a.js'),
+      parser: require.resolve('babel-eslint'),
     }),
     test({
       options: unusedExportsOptions,
       code: 'export const b = 2',
       filename: testFilePath('./no-unused-modules/file-b.js'),
+      parser: require.resolve('babel-eslint'),
     }),
     test({
       options: unusedExportsOptions,
       code: 'const c1 = 3; function c2() { return 3 }; export { c1, c2 }',
       filename: testFilePath('./no-unused-modules/file-c.js'),
+      parser: require.resolve('babel-eslint'),
     }),
     test({
       options: unusedExportsOptions,
       code: 'export function d() { return 4 }',
       filename: testFilePath('./no-unused-modules/file-d.js'),
+      parser: require.resolve('babel-eslint'),
     }),
     test({
       options: unusedExportsOptions,
       code: 'export class q { q0() {} }',
       filename: testFilePath('./no-unused-modules/file-q.js'),
+      parser: require.resolve('babel-eslint'),
     }),
     test({
       options: unusedExportsOptions,
       code: 'const e0 = 5; export { e0 as e }',
       filename: testFilePath('./no-unused-modules/file-e.js'),
+      parser: require.resolve('babel-eslint'),
     }),
     test({
       options: unusedExportsOptions,
       code: 'const l0 = 5; const l = 10; export { l0 as l1, l }; export default () => {}',
       filename: testFilePath('./no-unused-modules/file-l.js'),
+      parser: require.resolve('babel-eslint'),
     }),
     test({
       options: unusedExportsOptions,
       code: 'const o0 = 0; const o1 = 1; export { o0, o1 as o2 }; export default () => {}',
       filename: testFilePath('./no-unused-modules/file-o.js'),
+      parser: require.resolve('babel-eslint'),
     }),
   ],
   invalid: [
@@ -234,7 +242,72 @@ ruleTester.run('no-unused-modules', rule, {
   ],
 });
 
-// test for export from
+
+describe('dynamic imports', () => {
+  if (semver.satisfies(eslintPkg.version, '< 6')) {
+    beforeEach(function () {
+      this.skip();
+    });
+    return;
+  }
+
+  // test for unused exports with `import()`
+  ruleTester.run('no-unused-modules', rule, {
+    valid: [
+      test({
+        options: unusedExportsOptions,
+        code: `
+            export const a = 10
+            export const b = 20
+            export const c = 30
+            const d = 40
+            export default d
+            `,
+        parser: require.resolve('babel-eslint'),
+        filename: testFilePath('./no-unused-modules/exports-for-dynamic-js.js'),
+      }),
+    ],
+    invalid: [
+      test({
+        options: unusedExportsOptions,
+        code: `
+        export const a = 10
+        export const b = 20
+        export const c = 30
+        const d = 40
+        export default d
+        `,
+        parser: require.resolve('babel-eslint'),
+        filename: testFilePath('./no-unused-modules/exports-for-dynamic-js-2.js'),
+        errors: [
+          error(`exported declaration 'a' not used within other modules`),
+          error(`exported declaration 'b' not used within other modules`),
+          error(`exported declaration 'c' not used within other modules`),
+          error(`exported declaration 'default' not used within other modules`),
+        ] }),
+    ],
+  });
+  typescriptRuleTester.run('no-unused-modules', rule, {
+    valid: [
+      test({
+        options: unusedExportsTypescriptOptions,
+        code: `
+            export const ts_a = 10
+            export const ts_b = 20
+            export const ts_c = 30
+            const ts_d = 40
+            export default ts_d
+            `,
+        parser: require.resolve('@typescript-eslint/parser'),
+        filename: testFilePath('./no-unused-modules/typescript/exports-for-dynamic-ts.ts'),
+      }),
+    ],
+    invalid: [
+    ],
+  });
+});
+
+// // test for export from
 ruleTester.run('no-unused-modules', rule, {
   valid: [
     test({