refactor(common): change missing NgSwitch provider error message (#41704)

change error message of invalid NgSwitch use and add corner cases tests

PR Close #41704

packages/common/src/directives/ng_switch.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {Directive, DoCheck, Host, Input, TemplateRef, ViewContainerRef} from '@angular/core';
+import {Directive, DoCheck, Host, Input, Optional, TemplateRef, ViewContainerRef, ɵRuntimeError as RuntimeError, ɵRuntimeErrorCode as RuntimeErrorCode} from '@angular/core';
 
 export class SwitchView {
   private _created = false;
@@ -197,7 +197,11 @@ export class NgSwitchCase implements DoCheck {
 
   constructor(
       viewContainer: ViewContainerRef, templateRef: TemplateRef<Object>,
-      @Host() private ngSwitch: NgSwitch) {
+      @Optional() @Host() private ngSwitch: NgSwitch) {
+    if ((typeof ngDevMode === 'undefined' || ngDevMode) && !ngSwitch) {
+      throwNgSwitchProviderNotFoundError('ngSwitchCase', 'NgSwitchCase');
+    }
+
     ngSwitch._addCase();
     this._view = new SwitchView(viewContainer, templateRef);
   }
@@ -228,7 +232,20 @@ export class NgSwitchCase implements DoCheck {
 export class NgSwitchDefault {
   constructor(
       viewContainer: ViewContainerRef, templateRef: TemplateRef<Object>,
-      @Host() ngSwitch: NgSwitch) {
+      @Optional() @Host() ngSwitch: NgSwitch) {
+    if ((typeof ngDevMode === 'undefined' || ngDevMode) && !ngSwitch) {
+      throwNgSwitchProviderNotFoundError('ngSwitchDefault', 'NgSwitchDefault');
+    }
+
     ngSwitch._addDefault(new SwitchView(viewContainer, templateRef));
   }
 }
+
+function throwNgSwitchProviderNotFoundError(attrName: string, directiveName: string): never {
+  throw new RuntimeError(
+      RuntimeErrorCode.TEMPLATE_STRUCTURE_ERROR,
+      `An element with the "${attrName}" attribute ` +
+          `(matching the "${
+              directiveName}" directive) must be located inside an element with the "ngSwitch" attribute ` +
+          `(matching "NgSwitch" directive)`);
+}

packages/common/test/directives/ng_switch_spec.ts

@@ -7,8 +7,8 @@
  */
 
 import {CommonModule} from '@angular/common';
-import {Attribute, Component, Directive, TemplateRef, ViewChild} from '@angular/core';
+import {Attribute, Component, Directive, TemplateRef, ViewChild,} from '@angular/core';
-import {ComponentFixture, TestBed} from '@angular/core/testing';
+import {ComponentFixture, TestBed, waitForAsync} from '@angular/core/testing';
 import {expect} from '@angular/platform-browser/testing/src/matchers';
 
 {
@@ -176,6 +176,24 @@ import {expect} from '@angular/platform-browser/testing/src/matchers';
         detectChangesAndExpectText('when b1;when b2;');
       });
 
+      it('should throw error when ngSwitchCase is used outside of ngSwitch', waitForAsync(() => {
+           const template = '<div [ngSwitch]="switchValue"></div>' +
+               '<div *ngSwitchCase="\'a\'"></div>';
+
+           expect(() => createTestComponent(template))
+               .toThrowError(
+                   'NG0305: An element with the "ngSwitchCase" attribute (matching the "NgSwitchCase" directive) must be located inside an element with the "ngSwitch" attribute (matching "NgSwitch" directive)');
+         }));
+
+      it('should throw error when ngSwitchDefault is used outside of ngSwitch', waitForAsync(() => {
+           const template = '<div [ngSwitch]="switchValue"></div>' +
+               '<div *ngSwitchDefault></div>';
+
+           expect(() => createTestComponent(template))
+               .toThrowError(
+                   'NG0305: An element with the "ngSwitchDefault" attribute (matching the "NgSwitchDefault" directive) must be located inside an element with the "ngSwitch" attribute (matching "NgSwitch" directive)');
+         }));
+
       it('should support nested NgSwitch on ng-container with ngTemplateOutlet', () => {
         fixture = TestBed.createComponent(ComplexComponent);
         detectChangesAndExpectText('Foo');

packages/core/src/core_private_export.ts

@@ -24,6 +24,7 @@ export {CodegenComponentFactoryResolver as ɵCodegenComponentFactoryResolver} fr
 export {clearResolutionOfComponentResourcesQueue as ɵclearResolutionOfComponentResourcesQueue, resolveComponentResources as ɵresolveComponentResources} from './metadata/resource_loading';
 export {ReflectionCapabilities as ɵReflectionCapabilities} from './reflection/reflection_capabilities';
 export {GetterFn as ɵGetterFn, MethodFn as ɵMethodFn, SetterFn as ɵSetterFn} from './reflection/types';
+export {RuntimeError as ɵRuntimeError, RuntimeErrorCode as ɵRuntimeErrorCode} from './render3/error_code';
 export {allowSanitizationBypassAndThrow as ɵallowSanitizationBypassAndThrow, BypassType as ɵBypassType, getSanitizationBypassType as ɵgetSanitizationBypassType, SafeHtml as ɵSafeHtml, SafeResourceUrl as ɵSafeResourceUrl, SafeScript as ɵSafeScript, SafeStyle as ɵSafeStyle, SafeUrl as ɵSafeUrl, SafeValue as ɵSafeValue, unwrapSafeValue as ɵunwrapSafeValue} from './sanitization/bypass';
 export {_sanitizeHtml as ɵ_sanitizeHtml} from './sanitization/html_sanitizer';
 export {_sanitizeUrl as ɵ_sanitizeUrl} from './sanitization/url_sanitizer';

packages/core/src/render3/error_code.ts

@@ -27,6 +27,7 @@ export const enum RuntimeErrorCode {
   PIPE_NOT_FOUND = '302',
   UNKNOWN_BINDING = '303',
   UNKNOWN_ELEMENT = '304',
+  TEMPLATE_STRUCTURE_ERROR = '305'
 
   // Styling Errors