fix(@angular/build): remove every output of a deleted asset in watch mode

The previous asset state was keyed by source file, so an asset copied to several destinations
(two asset entries with the same input, or one copy per locale with `localize`) kept only the last
destination. Deleting the source during `ng build --watch` then removed only that copy and left
the others in the output directory.

Author: MeAkib

packages/angular/build/src/builders/application/build-action.ts

@@ -314,11 +314,11 @@ function* emitOutputResults(
   }
 
   // Initially assume all previous assets files have been removed
-  const removedAssetFiles = new Map(previousAssetsInfo);
+  const removedAssetFiles = new Set(previousAssetsInfo);
   for (const { source, destination } of assetFiles) {
-    removedAssetFiles.delete(source);
+    removedAssetFiles.delete(destination);
 
-    if (!previousAssetsInfo.has(source)) {
+    if (!previousAssetsInfo.has(destination)) {
       incrementalResult.added.push(destination);
       incrementalResult.background = false;
     } else if (changes.modified.has(source)) {
@@ -353,7 +353,7 @@ function* emitOutputResults(
       path,
       type,
     })),
-    ...Array.from(removedAssetFiles.values(), (path) => ({
+    ...Array.from(removedAssetFiles, (path) => ({
       path,
       type: BuildOutputFileType.Browser,
     })),

packages/angular/build/src/builders/application/tests/behavior/rebuild-assets_spec.ts

@@ -76,5 +76,39 @@ describeBuilder(buildApplication, APPLICATION_BUILDER_INFO, (harness) => {
         },
       ]);
     });
+
+    it('remove all outputs of a deleted asset copied to multiple destinations', async () => {
+      harness.useTarget('build', {
+        ...BASE_OPTIONS,
+        assets: [
+          {
+            glob: '**/*',
+            input: 'public',
+          },
+          {
+            glob: '**/*',
+            input: 'public',
+            output: 'static',
+          },
+        ],
+        watch: true,
+      });
+
+      await harness.executeWithCases([
+        async ({ result }) => {
+          expect(result?.success).toBeTrue();
+          harness.expectFile('dist/browser/asset.txt').toExist();
+          harness.expectFile('dist/browser/static/asset.txt').toExist();
+
+          await harness.removeFile('public/asset.txt');
+        },
+
+        ({ result }) => {
+          expect(result?.success).toBeTrue();
+          harness.expectFile('dist/browser/asset.txt').toNotExist();
+          harness.expectFile('dist/browser/static/asset.txt').toNotExist();
+        },
+      ]);
+    });
   });
 });

packages/angular/build/src/tools/esbuild/bundler-execution-result.ts

@@ -31,7 +31,7 @@ export interface RebuildState {
     string,
     { hash: string; type: BuildOutputFileType; path: string }
   >;
-  previousAssetsInfo: ReadonlyMap<string, string>;
+  previousAssetsInfo: ReadonlySet<string>;
   templateUpdates?: Map<string, string>;
 }
 
@@ -176,9 +176,8 @@ export class ExecutionResult {
       previousOutputInfo: new Map(
         this.outputFiles.map(({ path, hash, type }) => [`${type}:${path}`, { hash, type, path }]),
       ),
-      previousAssetsInfo: new Map(
-        this.assetFiles.map(({ source, destination }) => [source, destination]),
-      ),
+      // Tracked by destination since one source can be copied to several outputs (e.g. per locale).
+      previousAssetsInfo: new Set(this.assetFiles.map(({ destination }) => destination)),
       templateUpdates: this.templateUpdates,
     };
   }