path: root/doc/Money.dox

/*! \page money_example Money, a step by step example

\section Table of contents

  - \ref sec_setting_vc
  - \ref sec_setting_unix
  - \ref sec_running_test
  - \ref sec_adding_testfixture
  - \ref sec_first_tests
  - \ref sec_more_tests
  - \ref sec_credits

  The example explored in this article can be found in \c examples/Money/.



\section sec_setting_vc Setting up your project (VC++)

\subsection sec_install Compiling and installing CppUnit libaries

In the following document, $CPPUNIT is the directory where you unpacked %CppUnit:
~~~~~
$CPPUNIT/:
  include/
  lib/
  src/
    cppunit/
~~~~~

First, you need to compile %CppUnit libraries:
- Open the `$CPPUNIT/src/CppUnitLibrariesXXXX.sln` workspace in VC++.
- In the 'Build' menu, select 'Batch Build...'
- In the batch build dialog, select all projects and press the build button.
- The resulting libraries can be found in the `$CPPUNIT/lib/` directory.

Once it is done, you need to tell VC++ where are the includes and libraries
to use them in other projects. Open the 'Tools/Options...' dialog, and in the
'Directories' tab, select 'include files' in the combo. Add a new entry that
points to `$CPPUNIT/include/`. Change to 'libraries files' in the combo and 
add a new entry for `$CPPUNIT/lib/`. Repeat the process with 'source files' 
and add `$CPPUNIT/src/cppunit/`.

\subsection sec_getting_started Getting started

Creates a new console application ('a simple application' template will do).
Let's link %CppUnit library to our project. In the project settings:
- In tab 'C++', combo 'Code generation', set the combo to 'Multithreaded DLL'
for the release configuration, and 'Debug Multithreaded DLL' for the debug
configure,
- In tab 'C++', combo 'C++ langage', for All Configurations, check 
'enable Run-Time Type Information (RTTI)',
- In tab 'Link', in the 'Object/library modules' field, add cppunitd.lib for
the debug configuration, and cppunit.lib for the release configuration.

We're done !


  
    
      
        
          
\section sec_setting_unix Setting up your project (Unix)
We'll use \c autoconf and \c automake to make it simple to 
create our build environment. Create a directory somewhere to 
hold the code we're going to build. Create \c configure.in and 
\c Makefile.am in that directory to get started.

<tt>configure.ac</tt>
\verbatim
dnl Process this file with autoconf to produce a configure script.
AC_INIT([money],[0.1])
AC_CONFIG_SRCDIR(Makefile.am)
AM_INIT_AUTOMAKE
PKG_CHECK_MODULES([CPPUNIT], [cppunit >= 1.11.6])
AC_PROG_CXX
AC_PROG_CC
AC_PROG_INSTALL
AC_OUTPUT(Makefile)\endverbatim

<tt>Makefile.am</tt>
\verbatim
# Rules for the test code (use `make check` to execute)
TESTS = MoneyApp
check_PROGRAMS = $(TESTS)
MoneyApp_SOURCES = Money.h MoneyTest.h MoneyTest.cpp MoneyApp.cpp
MoneyApp_CXXFLAGS = $(CPPUNIT_CFLAGS)
MoneyApp_LDADD = $(CPPUNIT_LIBS)\endverbatim


  
    
      
        
          
            
\section sec_running_test Running our tests

We have a main that doesn't do anything. Let's start by adding the mechanics
to run our tests (remember, test before you code ;-) ). For this example, 
we will use a TextTestRunner with the CompilerOutputter for post-build 
testing:

<tt>MoneyApp.cpp</tt>
\code
#include <cppunit/CompilerOutputter.h>
#include <cppunit/extensions/TestFactoryRegistry.h>
#include <cppunit/ui/text/TestRunner.h>


int main()
{
  // Get the top level suite from the registry
  CPPUNIT_NS::Test *suite = CPPUNIT_NS::TestFactoryRegistry::getRegistry().makeTest();

  // Adds the test to the list of test to run
  CPPUNIT_NS::TextUi::TestRunner runner;
  runner.addTest( suite );

  // Change the default outputter to a compiler error format outputter
  runner.setOutputter( new CPPUNIT_NS::CompilerOutputter( &runner.result(),
                                                          CPPUNIT_NS::stdCOut() ) );
  // Run the test.
  bool wasSucessful = runner.run();

  // Return error code 1 if the one of test failed.
  return wasSucessful ? 0 : 1;
}\endcode

\b  VC++: Compile and run (Ctrl+F5).

\b  Unix: First build. Since we don't have all the files yet, let's create them
  and build our application for the first time:
\verbatim
touch Money.h MoneyTest.h MoneyTest.cpp
aclocal -I /usr/local/share/aclocal # you may need to use /usr/share/aclocal instead
autoconf
touch NEWS README AUTHORS ChangeLog # To make automake happy
automake -a
./configure
make check\endverbatim

  Our application will report that everything
is fine and no tests were run. So let's add some tests...



\subsection sec_post_build Setting up automated post-build testing (VC++)

What does post-build testing means? It means that each time you compile,
the test are automatically run when the build finish. This is very
useful, if you compile often you can know that you just 'broke' something,
or that everything is still working fine.

Let's adds that to our project, In the project settings, in the 
'post-build step' tab:
- Select 'All configurations' (upper left combo)
- In the 'Post-build description', enter 'Unit testing...'
- In 'post-build command(s)', add a new line: <tt>\$(TargetPath)</tt>

<tt>\$(TargetPath)</tt> expands into the name of your application:
Debug\\MoneyApp.exe in debug configuration and Release\\MoneyApp.exe in release
configuration.

What we are doing is say to VC++ to run our application for each build. 
Notices the last line of \c main(), it returns a different error code, 
depending on weither or not a test failed. If the code returned by
an application is not 0 in post-build step, it tell VC++ that the build
step failed.

Compile. Notice that the application's output is now in the build window.
How convenient!

  (Unix: tips to integrate make check into various IDE?)


  
    
      
        
          
\section sec_adding_testfixture Adding the TestFixture

For this example, we are going to write a simple money class. Money
has an amount and a currency. Let's begin by creating a fixture where
we can put our tests, and add single test to test Money constructor:

<tt>MoneyTest.h:</tt>
\code
#ifndef MONEYTEST_H
#define MONEYTEST_H

#include <cppunit/extensions/HelperMacros.h>

class MoneyTest : public CPPUNIT_NS::TestFixture
{
  CPPUNIT_TEST_SUITE( MoneyTest );
  CPPUNIT_TEST( testConstructor );
  CPPUNIT_TEST_SUITE_END();

public:
  void setUp();
  void tearDown();

  void testConstructor();
};

#endif  // MONEYTEST_H\endcode

- CPPUNIT_TEST_SUITE declares that our Fixture's test suite.
- CPPUNIT_TEST adds a test to our test suite. The test is implemented 
by a method named testConstructor().
- setUp() and tearDown() are use to setUp/tearDown some fixtures. We are
not using any for now.

<tt>MoneyTest.cpp</tt>
\code
#include "MoneyTest.h"
#include "Money.h"

// Registers the fixture into the 'registry'
CPPUNIT_TEST_SUITE_REGISTRATION( MoneyTest );


void 
MoneyTest::setUp()
{
}


void 
MoneyTest::tearDown()
{
}


void 
MoneyTest::testConstructor()
{
  CPPUNIT_FAIL( "not implemented" );
}
\endcode

Compile. As expected, it reports that a test failed. Press the \c F4 key
(Go to next Error). VC++ jump right to our failed assertion CPPUNIT_FAIL.
We can not ask better in term of integration!
\verbatim
Compiling...
MoneyTest.cpp
Linking...
Unit testing...
.F
G:\prg\vc\Lib\cppunit\examples\money\MoneyTest.cpp(26):Assertion
Test name: MoneyTest.testConstructor
not implemented
Failures !!!
Run: 1   Failure total: 1   Failures: 1   Errors: 0
Error executing d:\winnt\system32\cmd.exe.

moneyappd.exe - 1 error(s), 0 warning(s)
\endverbatim

Well, we have everything set up, let's start doing some real testing.


  
    
      

  
\section sec_first_tests Our first tests

Let's write our first real test. A test is usually decomposed in three parts:
- setting up datas used by the test
- doing some processing based on those datas
- checking the result of the processing

\code
void 
MoneyTest::testConstructor()
{
  // Set up
  const std::string currencyFF( "FF" );
  const double longNumber = 12345678.90123;

  // Process
  Money money( longNumber, currencyFF );

  // Check
  CPPUNIT_ASSERT_EQUAL( longNumber, money.getAmount() );
  CPPUNIT_ASSERT_EQUAL( currencyFF, money.getCurrency() );
}\endcode

Well, we finally have a good start of what our Money class will
look like. Let's start implementing...

<tt>Money.h</tt>
\code
#ifndef MONEY_H
#define MONEY_H

#include <string>

class Money
{
public:
  Money( double amount, std::string currency )
    : m_amount( amount )
    , m_currency( m_currency )
  {
  }

  double getAmount() const
  {
    return m_amount;
  }

  std::string getCurrency() const
  {
    return m_currency;
  }

private:
  double m_amount;
  std::string m_currency;
};

#endif\endcode

Include <tt>Money.h</tt> in MoneyTest.cpp and compile.

Hum, an assertion failed! Press F4, and we jump to the assertion
that checks the currency of the constructed money object. The report
indicates that string is not equal to expected value. There is only
two ways for this to happen: the member was badly initialized or we
returned the wrong value. After a quick check, we find out it is the former.
Let's fix that:

<tt>Money.h</tt>
\code
  Money( double amount, std::string currency )
    : m_amount( amount )
    , m_currency( currency )
  {
  }\endcode

Compile. Our test finally pass!
Let's add some functionnality to our Money class.


  
    
      
        
          
            
\section sec_more_tests Adding more tests

\subsection sec_equal Testing for equality

  We want to check if two Money object are equal. Let's start by adding
a new test to the suite, then add our method:

<tt>MoneyTest.h</tt>
\code
  CPPUNIT_TEST_SUITE( MoneyTest );
  CPPUNIT_TEST( testConstructor );
  CPPUNIT_TEST( testEqual );
  CPPUNIT_TEST_SUITE_END();
public:
  ...
  void testEqual();
\endcode

<tt>MoneyTest.cpp</tt>
\code
void
MoneyTest::testEqual()
{
  // Set up
  const Money money123FF( 123, "FF" );
  const Money money123USD( 123, "USD" );
  const Money money12FF( 12, "FF" );
  const Money money12USD( 12, "USD" );

  // Process & Check
  CPPUNIT_ASSERT( money123FF == money123FF );     // ==
  CPPUNIT_ASSERT( money12FF != money123FF );      // != amount
  CPPUNIT_ASSERT( money123USD != money123FF );    // != currency
  CPPUNIT_ASSERT( money12USD != money123FF );     // != currency and != amount
}\endcode

  Let's implements \c operator \c == and \c operator \c != in Money.h:

<tt>Money.h</tt>
\code
class Money
{
public:
...
  bool operator ==( const Money &other ) const
  {
    return m_amount == other.m_amount  &&  
           m_currency == other.m_currency;
  }

  bool operator !=( const Money &other ) const
  {
    return (*this == other);
  }
};
\endcode

  Compile, run... Ooops... Press F4, it seems we're having trouble 
with \c operator \c !=. Let's fix that:
\code
  bool operator !=( const Money &other ) const
  {
    return !(*this == other);
  }\endcode

Compile, run. Finally got it working!



\subsection sec_opadd Adding moneys

  Let's add our test 'testAdd' to MoneyTest. You know the routine...

<tt>MoneyTest.h</tt>
\code
  ...
  CPPUNIT_TEST( testAdd );
  CPPUNIT_TEST_SUITE_END();
public:
  ...
  void testAdd();
\endcode

<tt>MoneyTest.cpp</tt>
\code
void 
MoneyTest::testAdd()
{
  // Set up
  const Money money12FF( 12, "FF" );
  const Money expectedMoney( 135, "FF" );

  // Process
  Money money( 123, "FF" );
  money += money12FF;

  // Check
  CPPUNIT_ASSERT( expectedMoney == money );           // add works
  CPPUNIT_ASSERT( &money == &(money += money12FF) );  // add returns ref. on 'this'.
}\endcode

  While writing that test case, you ask yourself, what is the result of
adding money of different currencies? Obviously this is an error and it should be
reported, for example, by throwing an exception (e.g. \c IncompatibleMoneyError)
when the currencies are not equal. We will write another test case
for this later. For now let's get our testAdd() case working:

<tt>Money.h</tt>
\code
class Money
{
public:
...
  Money &operator +=( const Money &other )
  {
    m_amount += other.m_amount;
    return *this;
  }
}; \endcode

Compile, run. Miracle, everything is fine! Just to be sure the test is indeed
working, in the above code, change \c m_amount \c += to \c -=. Build and 
check that it fails (always be suspicious of tests that work the first 
time: you may have forgotten to add it to the suite for example)! 
Change the code back so that all tests work.

Let's write the incompatible money test case before we forget about it...
That test case expects an \c IncompatibleMoneyError exception to be thrown. 
You can check that with %CppUnit:

<tt>MoneyTest.h</tt>
\code
...
#include "Money.h"
...
  CPPUNIT_TEST_EXCEPTION( testAddThrow, IncompatibleMoneyError );
  CPPUNIT_TEST_SUITE_END();
public:
  ...
  void testAddThrow();
};\endcode

By convention, you end the name of such tests with \c 'Throw'. That way, you
know the test expects an exception to be thrown. Let's write our test case:

<tt>MoneyTest.cpp</tt>
\code
void 
MoneyTest::testAddThrow()
{
  // Set up
  const Money money123FF( 123, "FF" );

  // Process
  Money money( 123, "USD" );
  money += money123FF;        // should throw an exception
}
\endcode

  Compile... Ooops, forgot to declare the exception class. Let's do that:

<tt>Money.h</tt>
\code
#include <string>
#include <stdexcept>

class IncompatibleMoneyError : public std::runtime_error
{
public:
  IncompatibleMoneyError() : runtime_error( "Incompatible moneys" )
  {
  }
};
\endcode

  Compile. As expected, testAddThrow() fails... Let's fix that:

<tt>Money.h</tt>
\code
  Money &operator +=( const Money &other )
  {
    if ( m_currency != other.m_currency )
      throw IncompatibleMoneyError();

    m_amount += other.m_amount;
    return *this;
  }\endcode

  Compile. Our test finaly passes!

  TODO:
- How to use CPPUNIT_ASSERT_EQUALS with Money
- Copy constructor/Assignment operator
- Introducing fixtures
- ?


  
    
      
        
\section sec_credits Credits
This article was written by Baptiste Lepilleur. Unix configuration & set up 
by Phil Verghese. Inspired from many others (JUnit, Phil's cookbook...), 
and all the newbies around that keep asking me for the 
'Hello world' example ;-)



*/