public void AssertCustom_ShouldInvokeOnParamMock() { // Arrange MockMockMethodWithParam <string> mockMockMethodWithParam = new MockMockMethodWithParam <string> .Builder().AssertCustom().Build(); MockMockMethodWithResponse <bool> mockMockMethodWithResponse = new MockMockMethodWithResponse <bool> .Builder().Build(); MockMethodWithParamAndResponse <string, bool> subject = new ReflectionObject <MockMethodWithParamAndResponse <string, bool> >("methodName", mockMockMethodWithParam, mockMockMethodWithResponse).Object(); // Act subject.AssertCustom(o => o.Should().Be("expected")); // Assert mockMockMethodWithParam.AssertAssertCustomInvoked(); }