Introduction
C++ is a powerful, versatile language, but when it comes to unit testing in C++, developers often face a steep learning curve. From dealing with tightly coupled legacy C++ code to mocking static functions and global variables, the challenges of C++ testing can feel overwhelming. Fortunately, Typemock Isolator++ provides innovative solutions that simplify even the most complex testing scenarios.
In this blog, we’ll explore three common pain points in C++ unit testing and how Isolator++ addresses them effectively, helping developers deliver high-quality code with confidence.
Mocking Non-Virtual Methods
The Challenge
Traditional C++ mocking frameworks often require methods to be virtual to create test doubles. This limitation can lead to extensive refactoring or compromises in code design.
The Solution
Typemock Isolator++ overcomes this limitation by allowing the mocking of non-virtual methods without altering the production code.
Example:
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#include "Isolator++/Isolator++.h" class MyClass { public: int NonVirtualMethod() { return 5; } }; void TestNonVirtualMethod() { // Arrange MyClass* fakeInstance = FAKE<MyClass>(); WHEN_CALLED(fakeInstance->NonVirtualMethod()).Return(10); // Act int result = fakeInstance->NonVirtualMethod(); // Assert assert(result == 10); } |
In this example, NonVirtualMethod is mocked to return 10 instead of its original implementation. This demonstrates how mocking non-virtual methods in C++ becomes effortless with Isolator++.
Faking Static Functions
The Challenge
Static functions can be challenging to mock due to their global state and direct nature of invocation.
The Solution
Isolator++ simplifies this by allowing static functions in C++ to be faked seamlessly, offering greater test flexibility.
Example:
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#include "Isolator++/Isolator++.h" class MyClass { public: static int StaticMethod() { return -1; } }; void TestStaticMethod() { // Arrange FAKE_STATICS(MyClass); WHEN_CALLED(MyClass::StaticMethod()).Return(10); // Act int result = MyClass::StaticMethod(); // Assert assert(result == 10); } |
Here, StaticMethod is faked to return 10, demonstrating how Isolator++ handles the complexities of mocking static methods in C++.
Recursive Fakes
The Challenge
Testing complex object hierarchies often requires extensive setup for mocking multiple nested methods.
The Solution
Recursive fakes in Isolator++ automatically mock all methods and properties of a fake object, making it easier to manage nested dependencies in C++ testing.
Example:
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#include "Isolator++/Isolator++.h" class GPSLocation { public: int Latitude() { return 0; } }; class Address { public: GPSLocation* GetLocation() { return new GPSLocation(); } }; class Person { public: Address* GetAddress() { return new Address(); } }; void TestRecursiveFakes() { // Arrange Person* fakePerson = FAKE<Person>(); WHEN_CALLED(fakePerson->GetAddress()->GetLocation()->Latitude()).Return(10); // Act int latitude = fakePerson->GetAddress()->GetLocation()->Latitude(); // Assert assert(latitude == 10); } |
In this scenario, GetAddress and GetLocation methods return recursive fakes, enabling simpler and more efficient testing of C++ object hierarchies without extensive setup.
Making Legacy Code Testable
The Challenge
Legacy C++ codebases often lack modern patterns like dependency injection, making them difficult to test without significant refactoring.
The Solution
Isolator++ eliminates the need for invasive refactoring by allowing you to mock C++ legacy code directly, simplifying testing.
Example
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// Arrange: Fake an instance of a legacy class LegacyClass* fakeInstance = Fake<LegacyClass>(); WHEN_CALLED(fakeInstance->LegacyMethod).Ignore(); // Act: Call the legacy method fakeInstance->LegacyMethod(); // Assert: Ensure no exception or unwanted behavior ASSERT_TRUE(true); // Simplifies testing for void methods |
By making legacy C++ code testable without modifications, Isolator++ ensures developers can improve code quality without fighting technical debt.
Conclusion
C++ developers no longer need to struggle with the complexities of unit testing. Typemock Isolator++ empowers you to overcome the most daunting testing challenges, from mocking non-virtual methods to taming static functions and global variables, all while ensuring legacy codebases remain testable and maintainable.
Whether you’re working on embedded systems, high-performance applications, or enterprise software, Isolator++ is your ultimate ally in creating robust, reliable tests that support your development goals.
By making legacy code testable without modification, Isolator++ ensures you can focus on improving code quality and adding value, rather than fighting technical debt.
Start simplifying your C++ testing today! Learn more about Typemock Isolator++ and how it can transform your testing experience.
