test: verify that link in outputpath is not deleted at source

Closes: #15183

Author: alan-agius4

packages/angular_devkit/build_angular/test/browser/output-path_spec_large.ts

@@ -8,6 +8,7 @@
 
 import { Architect } from '@angular-devkit/architect';
 import { getSystemPath, join, virtualFs } from '@angular-devkit/core';
+import * as fs from 'fs';
 import { browserBuild, createArchitect, host } from '../utils';
 
 
@@ -39,13 +40,42 @@ describe('Browser Builder output path', () => {
     await run.stop();
   });
 
+  it('deletes output path and unlink symbolic link', async () => {
+    // Write a file to the output path to later verify it was deleted.
+    host.writeMultipleFiles({
+      'src-link/dummy.txt': '',
+      'dist/file.txt': virtualFs.stringToFileBuffer('file'),
+    });
+
+    const distLinked = join(host.root(), 'dist', 'linked');
+
+    // create symbolic link
+    fs.symlinkSync(
+      getSystemPath(join(host.root(), 'src-link')),
+      getSystemPath(distLinked),
+      'junction',
+    );
+
+    expect(await host.exists(distLinked).toPromise()).toBe(true);
+
+    // Delete an app file to force a failed compilation.
+    // Failed compilations still delete files, but don't output any.
+    await host.delete(join(host.root(), 'src', 'app', 'app.component.ts')).toPromise();
+    const run = await architect.scheduleTarget(target);
+    const output = await run.result;
+    expect(output.success).toBe(false);
+
+    expect(await host.exists(join(host.root(), 'dist')).toPromise()).toBe(false);
+    expect(await host.exists(join(host.root(), 'src-link')).toPromise()).toBe(true);
+  });
+
   it('does not allow output path to be project root', async () => {
     const overrides = { outputPath: './' };
     const run = await architect.scheduleTarget(target, overrides);
     try {
       await run.result;
       expect('THE ABOVE LINE SHOULD THROW').toBe('');
-    } catch {}
+    } catch { }
     await run.stop();
   });