refactor(ivy): ngcc - fake core and tslib should be typings files (#25445)

Previously these fake files were full TypeScript source
files (`.ts`) but this is not necessary as we only need the
typings not the implementation.

PR Close #25445

packages/compiler-cli/ngcc/test/helpers/utils.ts

@@ -64,49 +64,38 @@ export function makeTestProgram(
 // TODO: unify this with the //packages/compiler-cli/test/ngtsc/fake_core package
 export function getFakeCore() {
   return {
-    name: 'node_modules/@angular/core/index.ts',
+    name: 'node_modules/@angular/core/index.d.ts',
     contents: `
       type FnWithArg<T> = (arg?: any) => T;
 
-      function callableClassDecorator(): FnWithArg<(clazz: any) => any> {
+      export declare const Component: FnWithArg<(clazz: any) => any>;
-        return null !;
+      export declare const Directive: FnWithArg<(clazz: any) => any>;
+      export declare const Injectable: FnWithArg<(clazz: any) => any>;
+      export declare const NgModule: FnWithArg<(clazz: any) => any>;
+
+      export declare const Input: any;
+
+      export declare const Inject: FnWithArg<(a: any, b: any, c: any) => void>;
+      export declare const Self: FnWithArg<(a: any, b: any, c: any) => void>;
+      export declare const SkipSelf: FnWithArg<(a: any, b: any, c: any) => void>;
+      export declare const Optional: FnWithArg<(a: any, b: any, c: any) => void>;
+
+      export declare class InjectionToken {
+        constructor(name: string);
       }
 
-      function callableParamDecorator(): FnWithArg<(a: any, b: any, c: any) => void> {
+      export declare interface ModuleWithProviders<T = any> {}
-        return null !;
-      }
-
-      function makePropDecorator(): any {
-      }
-
-      export const Component = callableClassDecorator();
-      export const Directive = callableClassDecorator();
-      export const Injectable = callableClassDecorator();
-      export const NgModule = callableClassDecorator();
-
-      export const Input = makePropDecorator();
-
-      export const Inject = callableParamDecorator();
-      export const Self = callableParamDecorator();
-      export const SkipSelf = callableParamDecorator();
-      export const Optional = callableParamDecorator();
-
-      export class InjectionToken {
-        constructor(name: string) {}
-      }
-
-      export interface ModuleWithProviders<T = any> {}
     `
   };
 }
 
 export function getFakeTslib() {
   return {
-    name: 'node_modules/tslib/index.ts',
+    name: 'node_modules/tslib/index.d.ts',
     contents: `
-    export function __decorate(decorators: any[], target: any, key?: string | symbol, desc?: any) {}
+    export declare function __decorate(decorators: any[], target: any, key?: string | symbol, desc?: any);
-    export function __param(paramIndex: number, decorator: any) {}
+    export declare function __param(paramIndex: number, decorator: any);
-    export function __metadata(metadataKey: any, metadataValue: any) {}
+    export declare function __metadata(metadataKey: any, metadataValue: any);
     `
   };
 }

packages/compiler-cli/ngcc/test/host/esm2015_host_import_helper_spec.ts

@@ -346,7 +346,7 @@ describe('Fesm2015ReflectionHost [import helper style]', () => {
               null;
 
           const expectedDeclarationNode = getDeclaration(
-              program, 'node_modules/@angular/core/index.ts', 'Directive',
+              program, 'node_modules/@angular/core/index.d.ts', 'Directive',
               isNamedVariableDeclaration);
           const actualDeclaration = host.getDeclarationOfIdentifier(identifierOfDirective !);
           expect(actualDeclaration).not.toBe(null);

packages/compiler-cli/ngcc/test/host/esm2015_host_spec.ts

@@ -1359,7 +1359,8 @@ describe('Esm2015ReflectionHost', () => {
                                         .initializer as ts.Identifier;
 
       const expectedDeclarationNode = getDeclaration(
-          program, 'node_modules/@angular/core/index.ts', 'Directive', isNamedVariableDeclaration);
+          program, 'node_modules/@angular/core/index.d.ts', 'Directive',
+          isNamedVariableDeclaration);
       const actualDeclaration = host.getDeclarationOfIdentifier(identifierOfDirective);
       expect(actualDeclaration).not.toBe(null);
       expect(actualDeclaration !.node).toBe(expectedDeclarationNode);
@@ -1419,9 +1420,7 @@ describe('Esm2015ReflectionHost', () => {
       const values = Array.from(exportDeclarations !.values())
                          .map(declaration => [declaration.node.getText(), declaration.viaModule]);
       expect(values).toEqual([
-        // TODO clarify what is expected here...
+        [`Directive: FnWithArg<(clazz: any) => any>`, null],
-        // [`Directive = callableClassDecorator()`, '@angular/core'],
-        [`Directive = callableClassDecorator()`, null],
         [`a = 'a'`, null],
         [`b = a`, null],
         [`c = foo`, null],

packages/compiler-cli/ngcc/test/host/esm5_host_import_helper_spec.ts

@@ -365,7 +365,7 @@ describe('Esm5ReflectionHost [import helper style]', () => {
               null;
 
           const expectedDeclarationNode = getDeclaration(
-              program, 'node_modules/@angular/core/index.ts', 'Directive',
+              program, 'node_modules/@angular/core/index.d.ts', 'Directive',
               isNamedVariableDeclaration);
           const actualDeclaration = host.getDeclarationOfIdentifier(identifierOfDirective !);
           expect(actualDeclaration).not.toBe(null);

packages/compiler-cli/ngcc/test/host/esm5_host_spec.ts

@@ -1514,7 +1514,8 @@ describe('Esm5ReflectionHost', () => {
                                         .initializer as ts.Identifier;
 
       const expectedDeclarationNode = getDeclaration(
-          program, 'node_modules/@angular/core/index.ts', 'Directive', isNamedVariableDeclaration);
+          program, 'node_modules/@angular/core/index.d.ts', 'Directive',
+          isNamedVariableDeclaration);
       const actualDeclaration = host.getDeclarationOfIdentifier(identifierOfDirective);
       expect(actualDeclaration).not.toBe(null);
       expect(actualDeclaration !.node).toBe(expectedDeclarationNode);
@@ -1590,9 +1591,7 @@ describe('Esm5ReflectionHost', () => {
       const values = Array.from(exportDeclarations !.values())
                          .map(declaration => [declaration.node.getText(), declaration.viaModule]);
       expect(values).toEqual([
-        // TODO: clarify what is expected here...
+        [`Directive: FnWithArg<(clazz: any) => any>`, null],
-        //[`Directive = callableClassDecorator()`, '@angular/core'],
-        [`Directive = callableClassDecorator()`, null],
         [`a = 'a'`, null],
         [`b = a`, null],
         [`c = foo`, null],