I'm working on a C++ application with a vast amount of DLLs. Now I am trying to Unit test them with the Microsoft Visual Studio C++ Test Framework. I need to unit test the internal logic, as the DLL is rather big and only the most necessary functions are exported. So i followed this tutorial: https://learn.microsoft.com/en-us/visualstudio/test/how-to-write-unit-tests-for-cpp-dlls?view=vs-2019#sameProject and executing the tests works pretty fine but when starting the application for the next time, I figured out that the DLL did not get loaded anymore. The reason was that the DLL-Layout has been modified by the Unit Test.
Before adding the test:
After adding the test:
It's pretty clear why these methods appear, but is there
any possibility to move them to the bottom end of the dll?
any other possibility to add tests to a DLL that are able to test not exported functions without converting the .dll into a .lib?
Thanks in advance!
Related
I am trying to test a dll that was created in C++, specifically to test certain functions. A few search results gave the solution as testing in visual studio by creating a simple unit test and referencing the dll as a project. But the solution is not very clear to me and there is no way to add the dll to the unit test project, as the only options are projects, solution, shared projects. I don't even see the browse button.
Does anyone have a solution or could you explain this solution provided here? I just want to be able to call the dll function, from a C++ class or project to test the input & output.
test dll
It is pretty straight forward actually.
In the DLL project you can create a native Unit test project and write test methods.
Here is the link to clear steps with screenshots - https://learn.microsoft.com/en-us/visualstudio/test/writing-unit-tests-for-c-cpp.
Edit: I am assuming you have access to DLL code.
We had a unit test project (exe, using NUnitLite) that referenced the main application to unit test code within the main application (an exe).
This used to work, but now Xamarin is giving an error that we can't reference an exe project.
Why is this?
What alternatives do people suggest for unit testing application code? It seems wrong to have to move all application code from the exe to an assembly just for the purposes of unit testing.
It looks like the feature was accidentally removed :-( Someone must have overlooked that valid, if uncommon, scenario. Please file a bug report on Xamarin.Studio and request this feature to be *re*enabled.
Until then I see two workarounds:
Build/execute the tests from a script (e.g. a Makefile). You can automate this to require less steps than using the IDE;
Add a pre-build step to your project to make a copy of the .exe and name it .dll. Then reference this copy of the assembly.
I have 63 DLL's with various C++ methods in each. I want to validate the output of some of the methods with fixed input values. I'm wondering if it is possible to do unit testing in the DLL itself during compilation build process.
So, the compilation build of DLL gives the results of the Unit Testing in the Output window of Visual Studio.
I know that I can validate this scenario by creating executable file and calling the methods. But, is it possible without executable file?
As others have said - testing "during compilation" does not make sense, so I'm assuming you mean testing during the build process, which is different and of course possible using post build steps etc.
You don't specify which version of Visual Studio you use, but if you have VS2012, there is an MSDN article that describes exactly how to do what you describe. See the link for the full instructions, I've attached a partial screenshot below
Taking your question verbatim, the answer is "no", because you can't test a DLL when you haven't even finished compiling it. Also, you need some kind of executable to load that DLL, so either you load it with a scripting language (Python with ctypes comes to mind) or you create an executable.
Calling that from a post-compile step in Visual Studio, as suggested by shivakumar is probably the only way to get the results into the output window. I personally prefer running this from an external build script, but I'm also cross-compiling a lot and I can't run things from a post-compile step there. This also makes it easier to debug the unit tests when something fails.
You have to wait compilation to complete so that there are no compilation error in the code.
In the post-build event you can add batch files which will run your unit test modules and validate the binaries generated after compilation.
You are asking for a thing that does not make sense. When you say "compiling" that means a very specific thing: invoking the compiler, before invoking the linker. But C++ code (and C++ unit tests) do not work like that. The compiler must finish compiling both your production code and your tests, and the object files must then be linked into libraries, executables, or both. A test framework must then execute the test code which calls your production code in order to get results. None of these steps are optional in C++.
Instead, you probably intended to ask if you could run the unit tests as part of the build (not compile). And the answer to that is an emphatic "yes!"
I'm guessing that your solution is likely structured into 63 or more individual DLL projects. For each production DLL you are going to test, such as Foo.DLL, I recommend you add a new FooTest project, with the unit test code added to the FooTest project. In FooTest, create a project dependency upon the Foo project, which will force FooTest to build after building Foo. In the FooTest project you would have two kinds of code modules: classes containing your unit tests, and a FooTest.cpp that would house the main() entrypoint of the FooTest.EXE program, invoking the testing framework, and outputting the results to the console.
Create your FooTest.cpp so that it's a console program. If you format your test executable's output so that it matches the output of the Visual Studio compiler, as in "filename.cpp(lineNo) : error: description of failure", Visual Studio will automatically navigate to the file and line if you click on it. Unit test frameworks such as CppUnit may already have a "CompilerOutputter" class that will properly format the output to match your compiler's errors.
In your FooTest project, you also need to set the input to the FooTest linker so that it can link in the production code you are trying to test. In the properties of the FooTest project, go to the Linker/Input tab and add the path to your Foo project's OBJ files to the Additional Dependencies. The line I use looks like this: $(SolutionDir)Foo\Debug\obj*.obj
In the Build Events properties of the FooTest project, invoke your new FooTest.EXE as a post-build step. Then, every time you click build, your code will be built and your unit tests will be executed. The project dependency will ensure that if you change your Foo code, you will compile, link, and execute the FooTest tests. And the console output ensures that your test results will appear as clickable output in your IDE.
You could create 63 separate unit test executables, or you could create one all-encompassing unit test executable. That's entirely your choice. If you are looking to make the builds and links happen quicker, you will probably want to have the separate executables; even though it's a bit more individual configuration work, you do it only once, and after that you retain the benefits of quick builds for small changes.
Now you're ready to do some serious coding.
I am tasked with managing a large code base written in vc++ 6.0, I need to start building unit test for portions of the code. I have set up CPPUnit and it works with my projects DLL's the problem I am facing is as follows. The legacy application is made up of 10 static libraries and one huge executable MFC application that contains 99% of the code. My unit test framework is running in another project within the same workspace and will test the 10 libraries no problem all include and references are ok, when I try to do the same for the large MFC application I get a linker error as I do not have a dll for the application. Is there any way to unit test the application without putting the test code directly inside the application.
You should carry on as you are:
You have one test application that references libraries.
You have one main application that also references those libraries.
Either move code from the main application into the existing libraries, or, preferably, move code into new libraries. Then your test application can access more code without ever referring to the application.
You know when you are done when the source for the application consists of one module which defines main() and everything else in in libraries which are tested by the test application.
My experience with unit testing is usually the opposite. Create a project for your test then import code from your other projects.
You can't link to the MFC application probably because your functions aren't exported. They exist, but have no mean to communicate with other applications unlike DLLs.
I know of no way to link against an executable file. Refactoring the code by moving the business logic to a DLL and leaving the application as a "Front-end" would be the most obvious solution. However, since it is legacy code it is likely more appropriate to simply duplicate the code for purposes of unit testing. This is not ideal, and since it is an MFC applicaiton may not be trivially easy.
To test your main application you can set up a test project which includes the source files you want to test - not sure how easy it is to achieve with VC6, do not have it at hand, but in VS2005 and later this is quite straightforward.
So in your solution you end up with a structure like this:
MyLegacySystem.sln
MyApplication.proj
Main.cpp
BusinessRules.cpp
MyApplicationUnitTests.proj
UnitTestsMain.cpp
BusinessRules.cpp
BusinessRulesTests.cpp
If for whatever reason you cannot include your source files in 2 projects, you can pull the sources into your test project by invoking the preprocessor magic:
BusinessRulesStub.cpp:
#include "..\src\BusinessRules.cpp"
However, this is essentially a temporary fix. As already suggested, in the end most of the code should be extracted into separate libraries.
If you can't refactor your project to move the business logic into a new static library, try linking your test project against your project's intermediate object files, which you can probably find in BigProject\debug or BigProject\debug\obj . You can't link to the .EXE as you've discovered.
This achieves the same results as the copy process that Chad suggested while avoiding the actual duplication of source code, which would be a really bad thing.
I recently received as a new task to maintain and improve existing code written in C++ with MS Visual Studio. The code builds into an exe file (not a dll). I would like to add unit tests for the code and the problem I encountered is how to organize my testing projects. Basically I want to have 2 projects, one would be the original project I received and the second the testing project.
I saw on the Internet that usually when the subject being tested is built into a dll it's quite easy you have to statically link in your testing project the lib built from the main project and you have access to the function being tested. But how can this be done when the subject under test is an exe file?
Surely you can arrange the solution into projects that share code, where one project outputs to exe and the other(s) to DLL?
Whatever the project deliverable is, unit testing is testing the smallest units: the functions. A unit test typically follows the tripe A pattern: Arrange (create the environment for the test), Act (invoke the method under test), Assert (verify the method behaved as expected).
There are several possible project[s] structures: modify the project so that it compiles into a DLL, a production executable and a unit test program. The executable source has to be as small as possible, possibly just the main() function that create an Application object. It is also possible to have three projects, one for the DLL, one for the application and the third one for the tests.
An alternative is to embed the unit tests inside the executable and to have a mean to invoke them, e.g. with a special --unit-test parameter.