From 9b9e7ad5cf4878909dafcbf955809eaad5aa61aa Mon Sep 17 00:00:00 2001
From: JoostK <joost.koehoorn@gmail.com>
Date: Sat, 10 Apr 2021 21:34:30 +0200
Subject: [PATCH] test(compiler-cli): disable `emitDecoratorMetadata` in the
 compiler test environment (#41557)

The `emitDecoratorMetadata` compiler option does not have to be enabled
as Angular decorators are transformed by the AOT compiler. Having the
option enabled in our tests can hide issues around import preservation,
as with `emitDecoratorMetadata` enabled the TypeScript compiler itself
does not elide imports even if they are only used in type-positions.
This is unlike having `emitDecoratorMetadata` disabled, however; in that
case the Angular compiler has to actively trick TypeScript into
retaining default imports when an identifier in a type-only position has
been reified into a value position for DI purposes.

A subsequent commit addresses a bug in default import preservation
that relies on this flag being `false`.

PR Close #41557
---
 packages/compiler-cli/test/ngtsc/env.ts        | 2 +-
 packages/compiler-cli/test/ngtsc/ngtsc_spec.ts | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/compiler-cli/test/ngtsc/env.ts b/packages/compiler-cli/test/ngtsc/env.ts
index baad8f3286..b456573d72 100644
--- a/packages/compiler-cli/test/ngtsc/env.ts
+++ b/packages/compiler-cli/test/ngtsc/env.ts
@@ -53,7 +53,7 @@ export class NgtscTestEnvironment {
 
     env.write(absoluteFrom('/tsconfig-base.json'), `{
       "compilerOptions": {
-        "emitDecoratorMetadata": true,
+        "emitDecoratorMetadata": false,
         "experimentalDecorators": true,
         "skipLibCheck": true,
         "noImplicitAny": true,
diff --git a/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts b/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts
index ae696115d8..f98377ea0f 100644
--- a/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts
+++ b/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts
@@ -4648,7 +4648,7 @@ function allTests(os: string) {
 
       env.driveMain();
       const jsContents = trim(env.getContents('test.js'));
-      expect(jsContents).toContain(`import { KeyCodes } from './keycodes';`);
+      expect(jsContents).toContain(`import * as i1 from "./keycodes";`);
       expect(jsContents).toMatch(setClassMetadataRegExp('type: i1.KeyCodes'));
     });