A script for adding test cases to a CppUnit test class

One of the problems with using CppUnit as the unit test framework in C++ is that adding a single test requires updating the code in two files and in total 3 places. A declaration in the header file, a macro in the header file to register the test and the test itself. This makes adding a test too hard, which means the tests themselves become too big because it is easier to add extra asserts to an existing test than to add a new test. Some of the newer C++ frameworks overcome this, but we have been using CppUnit for a long time and have many tests already written, so I do not really want to change frameworks.

To fix this, I created a small Python script to add a new test, so working from the command line, I just need to write:

    newtest TestCase testMyNewTest

Then the declaration and prototype are created. I don't need to even look at the header file, I can just go straight to the definition of the test function and add the test.

The header file for a CppUnit test case looks like this:

class TestCase : public CppUnit::TestFixture
{
    CPPUNIT_TEST_SUITE( TestCase );
    CPPUNIT_TEST( testSomething );
    CPPUNIT_TEST( testNextBit );
    CPPUNIT_TEST_SUITE_END();
 public:
    void    setUp();
    void    tearDown();

    void    testSomething();
    void    testNextBit();
};

And the source file

CPPUNIT_TEST_SUITE_REGISTRATION( TestCase );

void TestCase::testSomething()
{
	// test code here
}

void TestCase::testNextBit()
{
	// test code here
}

The script is very basic, it searches for the last CPPUNIT_TEST macro in the header and adds a macro for the new test case. Searches for the last test function, and adds a test after that. Then it adds a definition at the end of the source file.

The script makes two assumptions

• The name of the class matches the name of the file. So the above test class would be in TestCase.h and TestCase.cpp
• The test class already has at least one test function when the script is run. Since I use a separate script to generate the boilerplate test class with a single test this is always true in my case.

The script is available here in case it is of use to anyone else: newtest.py