From 0a9b7cb5c3e75cdc0da3ceb67339b70320bbc8f1 Mon Sep 17 00:00:00 2001
From: deku-nattsu <aymenbeta@gmail.com>
Date: Fri, 21 Nov 2025 14:53:05 +0100
Subject: [PATCH] fix(@schematics/angular): do not set `esModuleInterop` and
 `moduleResolution` when module is `preserve`

---
 .../migrations/use-application-builder/migration.ts | 10 ++++++++--
 .../use-application-builder/migration_spec.ts       | 13 +++++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/packages/schematics/angular/migrations/use-application-builder/migration.ts b/packages/schematics/angular/migrations/use-application-builder/migration.ts
index cc858b59de54..9e8c9204d67f 100644
--- a/packages/schematics/angular/migrations/use-application-builder/migration.ts
+++ b/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');
     }),
   ]);
 }
diff --git a/packages/schematics/angular/migrations/use-application-builder/migration_spec.ts b/packages/schematics/angular/migrations/use-application-builder/migration_spec.ts
index a8d50193958e..fd10352c6eac 100644
--- a/packages/schematics/angular/migrations/use-application-builder/migration_spec.ts
+++ b/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 { JsonObject } 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';
@@ -448,4 +449,16 @@ describe(`Migration to use the application builder`, () => {
 
     expect(devDependencies['postcss']).toBeUndefined();
   });
+
+  it('it should not add esModuleInterop and moduleResolution when module is preserve', async () => {
+    tree.overwrite(
+      'tsconfig.json',
+      JSON.stringify({
+        compilerOptions: { module: 'preserve' },
+      }),
+    );
+    const newTree = await schematicRunner.runSchematic(schematicName, {}, tree);
+    const { compilerOptions } = newTree.readJson('tsconfig.json') as JsonObject;
+    expect(compilerOptions).toEqual({ module: 'preserve' });
+  });
 });