Mocktail error: No method stub was called from within `when()` - dart

Question

I'm using mocktail 0.3.0 package to test the request() method from HttpAdapter class. This method should call post() method of the Client class of the http package.
class HttpAdapter {
static const headers = {
HttpHeaders.contentTypeHeader: 'application/json',
HttpHeaders.acceptHeader: 'application/json',
};
final Client client;
HttpAdapter(this.client);
Future<void> request({
required String url,
required String method,
HttpClientBody? body,
}) async {
await client.post(Uri.parse(url), headers: HttpAdapter.headers);
}
}
class ClientSpy extends Mock implements Client {
void mockPost(String url) {
when(() => post(
Uri.parse(url),
headers: any(named: 'headers'),
)).thenAnswer(
(_) async => Response('{}', HttpStatus.ok),
);
}
}
When I test using the code below, everything goes well:
void main() {
test('Should call post() with correct parameters', () async {
// Arrange
final client = ClientSpy();
final sut = HttpAdapter(client);
when(() => client.post(
Uri.parse(url),
headers: HttpAdapter.headers,
)).thenAnswer(
(_) async => Response('{}', HttpStatus.ok),
);
// Act
await sut.request(url: url, method: method);
// Assert
verify(() => client.post(
Uri.parse(url),
headers: HttpAdapter.headers,
));
});
}
But if I replace the when() instruction by mockPost() method I get the error: Bad state: No method stub was called from within 'when()'. Was a real method called, or perhaps an extension method?
void main() {
test('Should call post() with correct parameters', () async {
// Arrange
final client = ClientSpy();
final sut = HttpAdapter(client);
client.mockPost();
// Act
await sut.request(url: url, method: method);
// Assert
verify(() => client.post(
Uri.parse(url),
headers: HttpAdapter.headers,
));
});
}
What am I doing wrong?

Answer 1

I think I figured out the problem.
The ClientSpy class implements the Client class from http package.
The Client class has a method called post(), witch is the one I want to call.
However, http package has a post() function also (I did't know that). So, I was calling the post() function instead Client.post() method.
The code below is working fine now:
class ClientSpy extends Mock implements Client {
void mockPost(String url) {
when(() => this.post(
Uri.parse(url),
headers: any(named: 'headers'),
)).thenAnswer(
(_) async => Response('{}', HttpStatus.ok),
);
}
}
or
import 'package:http/http.dart' as http;
class ClientSpy extends Mock implements http.Client {
void mockPost(String url) {
when(() => post(
Uri.parse(url),
headers: any(named: 'headers'),
)).thenAnswer(
(_) async => Response('{}', HttpStatus.ok),
);
}
}