feat(language-service): add code fix for unused standalone imports (a…

…ngular#57605)

Adds an automatic code fix to the language service that will remove unused standalone imports.

PR Close angular#57605

packages/language-service/src/codefixes/all_codefixes_metas.ts

@@ -9,10 +9,12 @@
 import {fixInvalidBananaInBoxMeta} from './fix_invalid_banana_in_box';
 import {missingImportMeta} from './fix_missing_import';
 import {missingMemberMeta} from './fix_missing_member';
+import {fixUnusedStandaloneImportsMeta} from './fix_unused_standalone_imports';
 import {CodeActionMeta} from './utils';
 
 export const ALL_CODE_FIXES_METAS: CodeActionMeta[] = [
   missingMemberMeta,
   fixInvalidBananaInBoxMeta,
   missingImportMeta,
+  fixUnusedStandaloneImportsMeta,
 ];

packages/language-service/src/codefixes/fix_unused_standalone_imports.ts

@@ -0,0 +1,76 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {ErrorCode, ngErrorCode} from '@angular/compiler-cli/src/ngtsc/diagnostics';
+import tss from 'typescript';
+
+import {CodeActionMeta, FixIdForCodeFixesAll} from './utils';
+import {findFirstMatchingNode} from '../utils/ts_utils';
+
+/**
+ * Fix for [unused standalone imports](https://angular.io/extended-diagnostics/NG8113)
+ */
+export const fixUnusedStandaloneImportsMeta: CodeActionMeta = {
+  errorCodes: [ngErrorCode(ErrorCode.UNUSED_STANDALONE_IMPORTS)],
+  getCodeActions: () => [],
+  fixIds: [FixIdForCodeFixesAll.FIX_UNUSED_STANDALONE_IMPORTS],
+  getAllCodeActions: ({diagnostics}) => {
+    const changes: tss.FileTextChanges[] = [];
+
+    for (const diag of diagnostics) {
+      const {start, length, file, relatedInformation} = diag;
+      if (file === undefined || start === undefined || length == undefined) {
+        continue;
+      }
+
+      const node = findFirstMatchingNode(file, {
+        filter: (current): current is tss.ArrayLiteralExpression =>
+          current.getStart() === start &&
+          current.getWidth() === length &&
+          tss.isArrayLiteralExpression(current),
+      });
+
+      if (node === null) {
+        continue;
+      }
+
+      let newText: string;
+
+      // If `relatedInformation` is empty, it means that all the imports are unused.
+      // Replace the array with an empty array.
+      if (relatedInformation === undefined || relatedInformation.length === 0) {
+        newText = '[]';
+      } else {
+        // Otherwise each `relatedInformation` entry points to an unused import that should be
+        // filtered out. We make a set of ranges corresponding to nodes which will be deleted and
+        // remove all nodes that belong to the set.
+        const excludeRanges = new Set(
+          relatedInformation.map((info) => `${info.start}-${info.length}`),
+        );
+        const newArray = tss.factory.updateArrayLiteralExpression(
+          node,
+          node.elements.filter((el) => !excludeRanges.has(`${el.getStart()}-${el.getWidth()}`)),
+        );
+
+        newText = tss.createPrinter().printNode(tss.EmitHint.Unspecified, newArray, file);
+      }
+
+      changes.push({
+        fileName: file.fileName,
+        textChanges: [
+          {
+            span: {start, length},
+            newText,
+          },
+        ],
+      });
+    }
+
+    return {changes};
+  },
+};

packages/language-service/src/codefixes/utils.ts

@@ -137,4 +137,5 @@ export enum FixIdForCodeFixesAll {
   FIX_MISSING_MEMBER = 'fixMissingMember',
   FIX_INVALID_BANANA_IN_BOX = 'fixInvalidBananaInBox',
   FIX_MISSING_IMPORT = 'fixMissingImport',
+  FIX_UNUSED_STANDALONE_IMPORTS = 'fixUnusedStandaloneImports',
 }

packages/language-service/test/code_fixes_spec.ts

@@ -570,6 +570,98 @@ describe('code fixes', () => {
       ]);
     });
   });
+
+  describe('unused standalone imports', () => {
+    it('should fix imports array where some imports are not used', () => {
+      const files = {
+        'app.ts': `
+         import {Component, Directive, Pipe} from '@angular/core';
+
+         @Directive({selector: '[used]', standalone: true})
+         export class UsedDirective {}
+
+         @Directive({selector: '[unused]', standalone: true})
+         export class UnusedDirective {}
+
+         @Pipe({name: 'unused', standalone: true})
+         export class UnusedPipe {}
+
+         @Component({
+          selector: 'used-cmp',
+          standalone: true,
+          template: '',
+         })
+         export class UsedComponent {}
+
+         @Component({
+           template: \`
+            <section>
+              <div></div>
+              <span used></span>
+              <div>
+                <used-cmp/>
+              </div>
+            </section>
+           \`,
+           standalone: true,
+           imports: [UnusedDirective, UsedDirective, UnusedPipe, UsedComponent],
+         })
+         export class AppComponent {}
+       `,
+      };
+
+      const project = createModuleAndProjectWithDeclarations(env, 'test', files);
+      const appFile = project.openFile('app.ts');
+
+      const fixesAllActions = project.getCombinedCodeFix(
+        'app.ts',
+        FixIdForCodeFixesAll.FIX_UNUSED_STANDALONE_IMPORTS,
+      );
+      expectIncludeReplacementTextForFileTextChange({
+        fileTextChanges: fixesAllActions.changes,
+        content: appFile.contents,
+        text: '[UnusedDirective, UsedDirective, UnusedPipe, UsedComponent]',
+        newText: '[UsedDirective, UsedComponent]',
+        fileName: 'app.ts',
+      });
+    });
+
+    it('should fix imports array where all imports are not used', () => {
+      const files = {
+        'app.ts': `
+         import {Component, Directive, Pipe} from '@angular/core';
+
+         @Directive({selector: '[unused]', standalone: true})
+         export class UnusedDirective {}
+
+         @Pipe({name: 'unused', standalone: true})
+         export class UnusedPipe {}
+
+         @Component({
+           template: '',
+           standalone: true,
+           imports: [UnusedDirective, UnusedPipe],
+         })
+         export class AppComponent {}
+       `,
+      };
+
+      const project = createModuleAndProjectWithDeclarations(env, 'test', files);
+      const appFile = project.openFile('app.ts');
+
+      const fixesAllActions = project.getCombinedCodeFix(
+        'app.ts',
+        FixIdForCodeFixesAll.FIX_UNUSED_STANDALONE_IMPORTS,
+      );
+      expectIncludeReplacementTextForFileTextChange({
+        fileTextChanges: fixesAllActions.changes,
+        content: appFile.contents,
+        text: '[UnusedDirective, UnusedPipe]',
+        newText: '[]',
+        fileName: 'app.ts',
+      });
+    });
+  });
 });
 
 type ActionChanges = {