fix: correct replacement of useExisting providers

libs/ng-mocks/src/lib/mock/clone-providers.ts

@@ -49,7 +49,7 @@ const processTokens = (mockType: AnyType<any>, provider: any) => {
 const processOwnUseExisting = (sourceType: AnyType<any>, mockType: AnyType<any>, provider: any) => {
   const provide = funcGetProvider(provider);
   if (provider !== provide && provider.useExisting === sourceType) {
-    return toExistingProvider(provider, mockType);
+    return toExistingProvider(provide, mockType);
   }
   if (
     provider !== provide &&

tests/ng-mocks-render/use-existing.spec.ts

@@ -0,0 +1,72 @@
+import { CommonModule } from '@angular/common';
+import {
+  Component,
+  ContentChild,
+  Directive,
+  Input,
+  NgModule,
+  TemplateRef,
+} from '@angular/core';
+import { MockBuilder, MockRender, ngMocks } from 'ng-mocks';
+
+@Directive({
+  selector: '[tpl]',
+})
+class TplDirective {
+  @Input('tpl') public readonly name: string | null = null;
+
+  public constructor(public readonly tpl: TemplateRef<any>) {}
+}
+
+@Directive({
+  providers: [
+    {
+      provide: TplDirective,
+      useExisting: MockDirective,
+    },
+  ],
+  selector: '[mock]',
+})
+class MockDirective {
+  public constructor(public readonly tpl: TemplateRef<any>) {}
+}
+
+@Component({
+  selector: 'target',
+  template: `
+    <component>
+      <ng-template mock>rendered-mock</ng-template>
+    </component>
+  `,
+})
+class TargetComponent {}
+
+@Component({
+  selector: 'component',
+  template: ``,
+})
+class MockComponent {
+  @ContentChild(TplDirective, {} as any)
+  public readonly directive?: TplDirective;
+}
+
+@NgModule({
+  declarations: [
+    TargetComponent,
+    MockComponent,
+    MockDirective,
+    TplDirective,
+  ],
+  imports: [CommonModule],
+})
+class TargetModule {}
+
+describe('ng-mocks-render:use-existing', () => {
+  beforeEach(() => MockBuilder(TargetComponent, TargetModule));
+
+  it('substitutes in mocks correctly', () => {
+    MockRender(TargetComponent);
+    const component = ngMocks.findInstance(MockComponent);
+    expect(component.directive).toEqual(jasmine.any(MockDirective));
+  });
+});