fix(migrations): preserve type when using inject decorator (angular#57389)

Updates the migration so that it passes the type as a generic in the case of `@Inject(SOME_TOKEN) foo: SomeType`. This is done for two reasons: 1. It's a fairly common pattern and it ensures that the code can still be compiled. 2. It avoids leaving behind unused imports. PR Close angular#57389

Author: crisbeto

packages/core/schematics/ng-generate/inject-migration/migration.ts

@@ -526,6 +526,18 @@ function migrateInjectDecorator(
  injectedType = arrowFn.body.getText();
  }
  }
+ } else if (
+ // Pass the type for cases like `@Inject(FOO_TOKEN) foo: Foo`, because:
+ // 1. It guarantees that the type stays the same as before.
+ // 2. Avoids leaving unused imports behind.
+ // We only do this for type references since the `@Inject` pattern above is fairly common and
+ // apps don't necessarily type their injection tokens correctly, whereas doing it for literal
+ // types will add a lot of noise to the generated code.
+ type &&
+ (ts.isTypeReferenceNode(type) ||
+ (ts.isUnionTypeNode(type) && type.types.some(ts.isTypeReferenceNode)))
+ ) {
+ typeArguments = [type];
  }
 
  return {injectedType, typeArguments};

packages/core/schematics/test/inject_migration_spec.ts

@@ -114,7 +114,7 @@ describe('inject migration', () => {
  ``,
  `@Directive()`,
  `class MyDir {`,
- ` private foo = inject(FOO_TOKEN);`,
+ ` private foo = inject<Foo>(FOO_TOKEN);`,
  `}`,
  ]);
  });
@@ -271,7 +271,7 @@ describe('inject migration', () => {
  ` ]`,
  `})`,
  `class MyDir {`,
- ` private foo = inject(FOO_TOKEN, { optional: true });`,
+ ` private foo = inject<Foo>(FOO_TOKEN, { optional: true });`,
  `}`,
  ]);
  });
@@ -1431,7 +1431,7 @@ describe('inject migration', () => {
  `@Directive()`,
  `class MyDir {`,
  ` private foo = inject(Foo);`,
- ` readonly bar = inject(BAR_TOKEN);`,
+ ` readonly bar = inject<Bar>(BAR_TOKEN);`,
  ``,
  ` private value: number = this.foo.getValue();`,
  ` private otherValue: string = this.bar.getOtherValue();`,
@@ -1470,7 +1470,7 @@ describe('inject migration', () => {
  `@Directive()`,
  `class MyDir {`,
  ` private foo = inject(Foo);`,
- ` readonly bar = inject(BAR_TOKEN);`,
+ ` readonly bar = inject<Bar>(BAR_TOKEN);`,
  ``,
  ` private value: number = this.foo.getValue();`,
  ` private otherValue: string;`,
@@ -1599,7 +1599,7 @@ describe('inject migration', () => {
  `@Directive()`,
  `class MyDir {`,
  ` private foo = inject(Foo);`,
- ` readonly bar = inject(BAR_TOKEN);`,
+ ` readonly bar = inject<Bar>(BAR_TOKEN);`,
  ``,
  ` private 'my-value': number = this.foo.getValue();`,
  ` private 'my-other-value': string = this.bar.getOtherValue();`,