fix(core): improve TestBed declarations standalone error message (#45999

)

improve the error message developers get when adding a standalone
component in the TestBed.configureTestingModule's declarations array,
by making more clear the fact that this error originated from the
TestBed call

resolves #45923

PR Close #45999

packages/core/src/render3/jit/module.ts

@@ -202,6 +202,13 @@ export function isStandalone<T>(type: Type<T>) {
   return def !== null ? def.standalone : false;
 }
 
+export function generateStandaloneInDeclarationsError(type: Type<any>, location: string) {
+  const prefix = `Unexpected "${stringifyForError(type)}" found in the "declarations" array of the`;
+  const suffix = `"${stringifyForError(type)}" is marked as standalone and can't be declared ` +
+      'in any NgModule - did you intend to import it instead (by adding it to the "imports" array)?';
+  return `${prefix} ${location}, ${suffix}`;
+}
+
 function verifySemanticsOfNgModuleDef(
     moduleType: NgModuleType, allowDuplicateDeclarationsInRoot: boolean,
     importingModule?: NgModuleType): void {
@@ -280,10 +287,8 @@ function verifySemanticsOfNgModuleDef(
     type = resolveForwardRef(type);
     const def = getComponentDef(type) || getDirectiveDef(type) || getPipeDef(type);
     if (def?.standalone) {
-      errors.push(`Unexpected "${stringifyForError(type)}" declaration in "${
-          stringifyForError(moduleType)}" NgModule. "${
-          stringifyForError(
-              type)}" is marked as standalone and can't be declared in any NgModule - did you intend to import it?`);
+      const location = `"${stringifyForError(moduleType)}" NgModule`;
+      errors.push(generateStandaloneInDeclarationsError(type, location));
     }
   }
 

packages/core/test/acceptance/ng_module_spec.ts

@@ -124,7 +124,7 @@ describe('NgModule', () => {
         TestBed.createComponent(MyComp);
       })
           .toThrowError(
-              `Unexpected "MyComp" declaration in "MyModule" NgModule. "MyComp" is marked as standalone and can't be declared in any NgModule - did you intend to import it?`);
+              `Unexpected "MyComp" found in the "declarations" array of the "MyModule" NgModule, "MyComp" is marked as standalone and can't be declared in any NgModule - did you intend to import it instead (by adding it to the "imports" array)?`);
     });
 
     it('should throw when a standalone directive is added to NgModule declarations', () => {
@@ -154,7 +154,7 @@ describe('NgModule', () => {
         TestBed.createComponent(MyComp);
       })
           .toThrowError(
-              `Unexpected "MyDir" declaration in "MyModule" NgModule. "MyDir" is marked as standalone and can't be declared in any NgModule - did you intend to import it?`);
+              `Unexpected "MyDir" found in the "declarations" array of the "MyModule" NgModule, "MyDir" is marked as standalone and can't be declared in any NgModule - did you intend to import it instead (by adding it to the "imports" array)?`);
     });
 
     it('should throw when a standalone pipe is added to NgModule declarations', () => {
@@ -184,8 +184,25 @@ describe('NgModule', () => {
         TestBed.createComponent(MyComp);
       })
           .toThrowError(
-              `Unexpected "MyPipe" declaration in "MyModule" NgModule. "MyPipe" is marked as standalone and can't be declared in any NgModule - did you intend to import it?`);
+              `Unexpected "MyPipe" found in the "declarations" array of the "MyModule" NgModule, "MyPipe" is marked as standalone and can't be declared in any NgModule - did you intend to import it instead (by adding it to the "imports" array)?`);
     });
+
+    it('should throw a testing specific error when a standalone component is added to the configureTestingModule declarations',
+       () => {
+         @Component({
+           selector: 'my-comp',
+           template: '',
+           standalone: true,
+         })
+         class MyComp {
+         }
+
+         expect(() => {
+           TestBed.configureTestingModule({declarations: [MyComp]});
+         })
+             .toThrowError(
+                 `Unexpected "MyComp" found in the "declarations" array of the "TestBed.configureTestingModule" call, "MyComp" is marked as standalone and can't be declared in any NgModule - did you intend to import it instead (by adding it to the "imports" array)?`);
+       });
   });
 
   describe('destroy', () => {

packages/core/testing/src/r3_test_bed_compiler.ts

@@ -11,6 +11,7 @@ import {ApplicationInitStatus, Compiler, COMPILER_OPTIONS, Component, Directive,
 
 import {clearResolutionOfComponentResourcesQueue, isComponentDefPendingResolution, resolveComponentResources, restoreComponentResolutionQueue} from '../../src/metadata/resource_loading';
 import {ComponentDef, ComponentType} from '../../src/render3';
+import {generateStandaloneInDeclarationsError} from '../../src/render3/jit/module';
 
 import {MetadataOverride} from './metadata_override';
 import {ComponentResolver, DirectiveResolver, NgModuleResolver, PipeResolver, Resolver} from './resolvers';
@@ -26,6 +27,16 @@ function isTestingModuleOverride(value: unknown): value is TestingModuleOverride
       value === TestingModuleOverride.OVERRIDE_TEMPLATE;
 }
 
+function assertNoStandaloneComponents(
+    types: Type<any>[], resolver: Resolver<any>, location: string) {
+  types.forEach(type => {
+    const component = resolver.resolve(type);
+    if (component && component.standalone) {
+      throw new Error(generateStandaloneInDeclarationsError(type, location));
+    }
+  });
+}
+
 // Resolvers for Angular decorators
 type Resolvers = {
   module: Resolver<NgModule>,
@@ -107,6 +118,10 @@ export class R3TestBedCompiler {
   configureTestingModule(moduleDef: TestModuleMetadata): void {
     // Enqueue any compilation tasks for the directly declared component.
     if (moduleDef.declarations !== undefined) {
+      // Verify that there are no standalone components
+      assertNoStandaloneComponents(
+          moduleDef.declarations, this.resolvers.component,
+          '"TestBed.configureTestingModule" call');
       this.queueTypeArray(moduleDef.declarations, TestingModuleOverride.DECLARATION);
       this.declarations.push(...moduleDef.declarations);
     }