fix(@angular/build): avoid internal karma request cache for assets

The internal karma common middleware that handles requests converts
the to be cached data into a string when stored. This can lead to invalid data
when the cached string is then sent in a followup request if the original content
was not intended to be a string. To avoid this  problem, asset files are now
explicitly not cached by karma's middleware.
Ref: https://github.com/karma-runner/karma/blob/84f85e7016efc2266fa6b3465f494a3fa151c85c/lib/middleware/common.js#L72

Author: clydin

packages/angular/build/src/builders/karma/application_builder.ts

@@ -86,7 +86,7 @@ class AngularAssetsMiddleware {
 
     switch (file.origin) {
       case 'disk':
-        this.serveFile(file.inputPath, undefined, res);
+        this.serveFile(file.inputPath, undefined, res, undefined, undefined, /* doNotCache */ true);
         break;
       case 'memory':
         // Include pathname to help with Content-Type headers.

packages/angular/build/src/builders/karma/tests/behavior/rebuilds_spec.ts

@@ -68,5 +68,74 @@ describeKarmaBuilder(execute, KARMA_BUILDER_INFO, (harness, setupTarget) => {
 
       expect(buildCount).toBe(expectedSequence.length);
     });
+
+    it('correctly serves binary assets on rebuilds', async () => {
+      /**
+       * Compiled and base64 encoded WASM file for the following WAT:
+       * ```
+       *  (module
+       *    (export "multiply" (func $multiply))
+       *    (func $multiply (param i32 i32) (result i32)
+       *      local.get 0
+       *      local.get 1
+       *      i32.mul
+       *    )
+       *  )
+       * ```
+       */
+      const exportWasmBase64 =
+        'AGFzbQEAAAABBwFgAn9/AX8DAgEABwwBCG11bHRpcGx5AAAKCQEHACAAIAFsCwAXBG5hbWUBCwEACG11bHRpcGx5AgMBAAA=';
+      await harness.writeFiles({
+        './src/multiply.wasm': Buffer.from(exportWasmBase64, 'base64'),
+        './src/app/app.component.spec.ts': `
+            describe('AppComponent', () => {
+              it('should fetch WASM file with correct size', async () => {
+                const resp = await fetch('/multiply.wasm');
+                const data = await resp.arrayBuffer();
+                expect(data.byteLength).toBe(71);
+              });
+            });`,
+      });
+
+      harness.useTarget('test', {
+        ...BASE_OPTIONS,
+        watch: true,
+        assets: ['src/multiply.wasm'],
+      });
+
+      interface OutputCheck {
+        (result: BuilderOutput | undefined): Promise<void>;
+      }
+
+      const expectedSequence: OutputCheck[] = [
+        async (result) => {
+          // Karma run should succeed.
+          expect(result?.success).withContext('Initial test run should succeed').toBeTrue();
+          // Modify test file to trigger a rebuild
+          await harness.appendToFile(
+            'src/app/app.component.spec.ts',
+            `\n;console.log('modified');`,
+          );
+        },
+        async (result) => {
+          expect(result?.success).withContext('Test should succeed again').toBeTrue();
+        },
+      ];
+
+      const buildCount = await harness
+        .execute({ outputLogsOnFailure: true })
+        .pipe(
+          timeout(60000),
+          debounceTime(500),
+          concatMap(async ({ result }, index) => {
+            await expectedSequence[index](result);
+          }),
+          take(expectedSequence.length),
+          count(),
+        )
+        .toPromise();
+
+      expect(buildCount).toBe(expectedSequence.length);
+    });
   });
 });