fix(@schematics/angular): do not set esModuleInterop and moduleResolution when module is preserve

Author: Deku-nattsu

packages/schematics/angular/migrations/use-application-builder/migration.ts

@@ -362,10 +362,16 @@ export default function (): Rule {
     ),
     // Update main tsconfig
     updateJsonFile('tsconfig.json', (rootJson) => {
-      rootJson.modify(['compilerOptions', 'esModuleInterop'], true);
+      const module = rootJson.get(['compilerOptions', 'module']);
+      const hasPreserveModule = typeof module === 'string' && module.toLowerCase() === 'preserve';
+
+      if (!hasPreserveModule) {
+        rootJson.modify(['compilerOptions', 'esModuleInterop'], true);
+        rootJson.modify(['compilerOptions', 'moduleResolution'], 'bundler');
+      }
+
       rootJson.modify(['compilerOptions', 'downlevelIteration'], undefined);
       rootJson.modify(['compilerOptions', 'allowSyntheticDefaultImports'], undefined);
-      rootJson.modify(['compilerOptions', 'moduleResolution'], 'bundler');
     }),
   ]);
 }

packages/schematics/angular/migrations/use-application-builder/migration_spec.ts

@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.dev/license
  */
 
+import { isJsonObject } from '@angular-devkit/core';
 import { EmptyTree } from '@angular-devkit/schematics';
 import { SchematicTestRunner, UnitTestTree } from '@angular-devkit/schematics/testing';
 import { Builders, ProjectType, WorkspaceSchema } from '../../utility/workspace-models';
@@ -36,7 +37,10 @@ function createWorkSpaceConfig(tree: UnitTestTree) {
   };
 
   tree.create('/angular.json', JSON.stringify(angularConfig, undefined, 2));
-  tree.create('/tsconfig.json', JSON.stringify({}, undefined, 2));
+  tree.create(
+    '/tsconfig.json',
+    JSON.stringify({ compilerOptions: { module: 'preserve' } }, undefined, 2),
+  );
   tree.create('/package.json', JSON.stringify({}, undefined, 2));
 }
 
@@ -49,6 +53,23 @@ function addWorkspaceTarget(tree: UnitTestTree, targetName: string, targetEntry:
   tree.overwrite('/angular.json', JSON.stringify(workspaceContent));
 }
 
+function getCompilerOptionsValue(tree: UnitTestTree, filePath: string): Record<string, unknown> {
+  const json = tree.readJson(filePath);
+  if (isJsonObject(json) && isJsonObject(json.compilerOptions)) {
+    return json.compilerOptions;
+  }
+
+  throw new Error(`Cannot retrieve 'compilerOptions'.`);
+}
+
+function createJsonFile(tree: UnitTestTree, filePath: string, content: {}): void {
+  const stringifiedContent = JSON.stringify(content, undefined, 2);
+  if (tree.exists(filePath)) {
+    tree.overwrite(filePath, stringifiedContent);
+  } else {
+    tree.create(filePath, stringifiedContent);
+  }
+}
 describe(`Migration to use the application builder`, () => {
   const schematicName = 'use-application-builder';
   const schematicRunner = new SchematicTestRunner(
@@ -448,4 +469,14 @@ describe(`Migration to use the application builder`, () => {
 
     expect(devDependencies['postcss']).toBeUndefined();
   });
+
+  it('it should not add esModuleInterop and moduleResolution when module is preserve', async () => {
+    createJsonFile(tree, 'tsconfig.json', {
+      compilerOptions: { module: 'preserve' },
+    });
+    const newTree = await schematicRunner.runSchematic(schematicName, {}, tree);
+
+    const compilerOptions = getCompilerOptionsValue(newTree, 'tsconfig.json');
+    expect(compilerOptions).toEqual({ module: 'preserve' });
+  });
 });