MissingStubError when mocking DateTime: 'hashCode' / '==' / 'toString'

[boldt]

We're trying to migrate our mockito-tests to null-safety. We followed the null-safety guide.
Now we see the following issues, when we are "working" with the stubs (like expect or indexOf in an array):

1) MissingStubError: 'hashCode'

MissingStubError: 'hashCode'
No stub was found which matches the arguments of this method call:
hashCode

2) MissingStubError: '=='

MissingStubError: '=='
No stub was found which matches the arguments of this method call:
==(MockDeviceModel)

3) MissingStubError: 'toString'

MissingStubError: 'toString'
No stub was found which matches the arguments of this method call:
toString()

Our use case

Our codes works on lists. Thereore, our tests use a list of mocks and thus, tried to compare them, which fails finally.

Our setup

• dart: 2.13.0
• flutter: 2.2.0
• mockito: 5.0.8

Issue

Mocks do not handle hashCode / == / 'toString'

[boldt]

MWE for MissingStubError: 'toString'

@GenerateMocks([
  DateTime,
])
void main() {
  test("MissingStubError: 'toString'", () {
    var mockDateTime = MockDateTime();
    expect(mockDateTime, mockDateTime);
  });
}

Issue:

MissingStubError: 'toString'
No stub was found which matches the arguments of this method call:
toString()

Expected

expect should return true, when a mock is used.

[boldt]

MissingStubError: 'hashCode'

  test("MissingStubError: 'hashCode'", () {
    var mockDateTime0 = MockDateTime();
    var mockDateTime1 = MockDateTime();
    var arr0 = [mockDateTime0, mockDateTime1];
    var arr1 = [mockDateTime0, mockDateTime1];
    expect(arr0, arr1);
  });

Issue

MissingStubError: 'hashCode'
No stub was found which matches the arguments of this method call:
hashCode

[srawlins]

I think this might happen for any class which overrides toString, hashCode, or operator==, but it would be surprising that we haven't seen this error yet.

In any case, we do have bugs for classes which override these methods and add optional parameters, so we should fix the two in one go.

[srawlins]

This should be fixed in mockito 5.0.10.

[boldt]

I can confirm, that my borken tests succeed now.