This document describes very shortly how to install the [http://sourceforge.net/projects/cppunit/ CppUnit] framework under Unix and how to write and run a very simplistic test case. This should get you started with using CppUnit, so that you can follow and try out the examples given in the [http://cppunit.sourceforge.net/doc/lastest/cppunit_cookbook.html CppUnit CookBook].

Installing

Download the latest version of CppUnit from http://downloads.sourceforge.net/cppunit/cppunit-1.12.1.tar.gz.

Let us install it under /var/tmp/cppunit/install:

$ cd /var/tmp/
$ mv ~/cppunit-1.12.1.tar.gz .
$ tar xzf cppunit-1.12.1.tar.gz
$ ln -s cppunit-1.12.1 cppunit
$ cd cppunit
$ ./configure --prefix=`pwd`/install
$ make
$ make check
$ make install

Writing a simplistic test case

Suppose we write a class Complex for dealing with complex numbers. In the following code, the operator+ intentionally contains a bug:

class Complex { 
  friend bool   operator==(const Complex& a, const Complex& b);
  friend Complex operator+(const Complex& a, const Complex& b);
  double real, imaginary;
public:
  Complex( double r, double i = 0 )  : real(r), imaginary(i) {}
};

bool operator==( const Complex &a, const Complex &b )
{ 
  return a.real == b.real  &&  a.imaginary == b.imaginary; 
}

Complex operator+( const Complex &a, const Complex &b )
{ 
  // BUG! imaginary part should be 'a.imaginary + b.imaginary'
  return Complex(a.real + b.real, a.imaginary + b.real); 
}

Now let us write a CppUnit test case for this class:

#include <cppunit/TestCase.h>

class ComplexNumberTest : public CppUnit::TestCase { 
public: 
  ComplexNumberTest( std::string name ) : CppUnit::TestCase( name ) {}
  
  void runTest() {
    CPPUNIT_ASSERT( Complex (10, 1) == Complex (10, 1) );
    CPPUNIT_ASSERT( !(Complex (1, 1) == Complex (2, 2)) );
    CPPUNIT_ASSERT( Complex (1, 2) + Complex(3, 4) == Complex (4, 6));
  }
};


int main()
{
  ComplexNumberTest myTest("My first CppUnit test");
  
  myTest.runTest();
}

For this, we have to subclass the TestCase class and to override the method runTest(). To check a value, we call CPPUNIT_ASSERT(bool) and pass in an expression that is true if the test succeeds.

Compiling and running

Suppose we put all the above code into one file ComplexNumberTest.cpp. Then the following makefile will do the job for us:

INCLS   = -I/var/tmp/cppunit/install/include/
LIBDIRS = -L/var/tmp/cppunit/install/lib
LIBS    = -lcppunit -ldl # note that CppUnit needs libld.so!

# Implicit rule: How to make an executable from a .cpp-file
%: %.cpp
        ${CC} -o $@ $< ${CXXFLAGS} ${INCLS} ${LIBDIRS} ${LIBS}

runtest: ComplexNumberTest
        export LD_LIBRARY_PATH=/var/tmp/cppunit/install/lib && ./ComplexNumberTest

Note that CppUnit needs the library ld.so in the linking step.

Now we can compile and run the program:

$ make runtest
cc -o ComplexNumberTest ComplexNumberTest.cpp  -I/var/tmp/cppunit/install/include/ -L/var/tmp/cppunit/install/lib -lcppunit -ldl
export LD_LIBRARY_PATH=/var/tmp/cppunit/install/lib && ./ComplexNumberTest
terminate called after throwing an instance of 'CppUnit::Exception'
  what():  assertion failed
- Expression: Complex (1, 2) + Complex(3, 4) == Complex (4, 6)

/bin/sh: line 1:  1457 Aborted                 ./ComplexNumberTest

As you can see, the third assertion failed, which detects the bug in out operator+.

Now go on and read the rest of the [http://cppunit.sourceforge.net/doc/lastest/cppunit_cookbook.html CppUnit CookBook] and try out the examples given there.