I created a basic interceptor that removes a specific field from a response:
import {
CallHandler,
ExecutionContext,
Injectable,
NestInterceptor,
} from '@nestjs/common';
import { Observable } from 'rxjs';
import { map } from 'rxjs/operators';
export interface Response<T> {
data: T;
}
@Injectable()
export class Transform<T> implements NestInterceptor<T, Response<T>> {
intercept(
context: ExecutionContext,
next: CallHandler,
): Observable<Response<T>> {
return next.handle().pipe(
map((response) => {
delete response?.value?.name;
return response;
}),
);
}
}
I am trying to figure out how to write a test case for this interceptor. Specifically, I want to verify if the 'name' property is removed from the response. However, when I tried the following test case, the response came back as undefined:
it('should delete `name` from response if present', async () => {
transformInterceptor = new TransformRepoResponse();
const context = {
switchToHttp: () => ({
getRequest: () => jest.fn(),
}),
};
const next = {
handle: jest.fn().mockReturnValue({
pipe: jest.fn(),
}),
};
requestMock.method = 'GET';
const response = await transformInterceptor.intercept(context, next);
expect(response.value.name).toBe(undefined);
});