Mocks generated by @GenerateMocks do not implement secondary generic types for typed-mocks

[bertiepinnock]

Hi there,

I think I've noticed an issue with the @GenerateMocks annotation when it comes to applying secondary generic types (i.e. types of a type). For example the following class/mocks:

import 'package:mockito/annotations.dart';

@GenerateMocks([], customMocks: [MockSpec<Foo<Map<String, dynamic>>>()])
void main() {}

class Foo<T> {
  void doNothing(T arg) {}
}

Produces this as generated mock code:

// Mocks generated by Mockito 5.0.7 from annotations
// in project/test/test_mock.dart.
// Do not manually edit this file.

import 'package:mockito/mockito.dart' as _i1;

import 'test_mock.dart' as _i2;

// ignore_for_file: comment_references
// ignore_for_file: unnecessary_parenthesis

// ignore_for_file: prefer_const_constructors

// ignore_for_file: avoid_redundant_argument_values

/// A class which mocks [Foo].
///
/// See the documentation for Mockito's code generation for more information.
class MockFoo extends _i1.Mock implements _i2.Foo<Map> {
  MockFoo() {
    _i1.throwOnMissingStub(this);
  }

  @override
  void doNothing(Map<String, dynamic>? arg) =>
      super.noSuchMethod(Invocation.method(#doNothing, [arg]),
          returnValueForMissingStub: null);
}

This produces a compilation error on the MockFoo override of doNothing that states:
'MockFoo.doNothing' ('void Function(Map<String, dynamic>?)') isn't a valid override of 'Foo.doNothing' ('void Function(Map<dynamic, dynamic>)').dartinvalid_override

As far as I can tell, this is because when the MockFoo class is implementing Foo it is erasing the type parameters of the Map<String, dynamic> to just Map. If I manually change Foo<Map> to Foo<Map<String, dynamic>> it fixes the issue. I ran into this whilst mocking elements of the FlutterFire Firestore package which (in its current version) uses Map<String, dynamic> as a default type, so I can imagine it may cause problems for others too.

I did have a look over the documentation/issues and couldn't see anything open to cover this, but I won't be too surprised if I've just tried using something incorrectly.

Thanks!

[srawlins]

Good catch; on the surface this definitely looks like a bug, but I'm surprised we don't have tests for this...