public async Task AddAssignment_WithValidationMessages_ReturnsValidationMessages() { var input = _fixture.Create <AddAssignmentRequest>(); var expectedValidationMessages = _fixture.CreateMany <ValidationMessage>(); _assignmentValidator .Setup(x => x.ValidateRules(input)) .Returns(expectedValidationMessages); AddAssignmentResult result = await _sut.AddAssignmentAsync(input); result.Should().NotBeNull(); result.ValidationMessages.Should().BeEquivalentTo(expectedValidationMessages); }