test(@angular-devkit/build-angular): test build-optimizer reduction

Author: filipesilva

packages/angular_devkit/build_angular/test/browser/build-optimizer_spec_large.ts

@@ -6,14 +6,15 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import { runTargetSpec } from '@angular-devkit/architect/testing';
+import { DefaultTimeout, runTargetSpec } from '@angular-devkit/architect/testing';
 import { join, normalize, virtualFs } from '@angular-devkit/core';
-import { tap } from 'rxjs/operators';
+import { concatMap, tap } from 'rxjs/operators';
 import { browserTargetSpec, host } from '../utils';
 
 
 describe('Browser Builder build optimizer', () => {
   const outputPath = normalize('dist');
+  const fileName = join(outputPath, 'main.js');
 
   beforeEach(done => host.initialize().toPromise().then(done, done.fail));
   afterEach(done => host.restore().toPromise().then(done, done.fail));
@@ -23,10 +24,49 @@ describe('Browser Builder build optimizer', () => {
     runTargetSpec(host, browserTargetSpec, overrides).pipe(
       tap((buildEvent) => expect(buildEvent.success).toBe(true)),
       tap(() => {
-        const fileName = join(outputPath, 'main.js');
         const content = virtualFs.fileBufferToString(host.scopedSync().read(normalize(fileName)));
         expect(content).not.toMatch(/\.decorators =/);
       }),
     ).toPromise().then(done, done.fail);
   });
+
+  it('reduces bundle size', (done) => {
+    const noBoOverrides = { aot: true, optimization: true, vendorChunk: false };
+    const boOverrides = { ...noBoOverrides, buildOptimizer: true };
+
+    let noBoSize: number;
+    let boSize: number;
+
+    runTargetSpec(host, browserTargetSpec, noBoOverrides, DefaultTimeout * 3).pipe(
+      tap((buildEvent) => expect(buildEvent.success).toBe(true)),
+      tap(() => {
+        const noBoStats = host.scopedSync().stat(normalize(fileName));
+        if (!noBoStats) {
+          throw new Error('Main file has no stats');
+        }
+        noBoSize = noBoStats.size;
+      }),
+      concatMap(() => runTargetSpec(host, browserTargetSpec, boOverrides, DefaultTimeout * 3)),
+      tap((buildEvent) => expect(buildEvent.success).toBe(true)),
+      tap(() => {
+        const boStats = host.scopedSync().stat(normalize(fileName));
+        if (!boStats) {
+          throw new Error('Main file has no stats');
+        }
+        boSize = boStats.size;
+      }),
+      tap(() => {
+        const sizeDiff = Math.round(((boSize - noBoSize) / noBoSize) * 10000) / 100;
+        if (sizeDiff > -1 && sizeDiff < 0) {
+          throw new Error('Total size difference is too small, '
+            + 'build optimizer does not seem to have made any optimizations.');
+        }
+
+        if (sizeDiff > 1) {
+          throw new Error('Total size difference is positive, '
+            + 'build optimizer made the bundle bigger.');
+        }
+      }),
+    ).toPromise().then(done, done.fail);
+  });
 });