[Cppunit-devel] Re: Possible error in CppUnit documentation

[Baptiste L. <bl...@us...>]

Tina wrote:
> Hello,
>
> I'm a newbie of CppUnit, and I followed your "Money,a step by step
> example" in the "CppUnit Documentation Version 1.10.2".
>
> The steps of "Setting up your project(VC++)", "Running our tests",
> "Adding the TestFixture" and "Our first tests" went well. But in
> "Adding more tests", when I added the test "testAdd", there were some
> problems. In the documents, you wrote:
>
> MoneyTest.cpp
> 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_EQUAL( expectedMoney == money.getAmount() ); // +=
> works CPPUNIT_ASSERT( &money == &(money += money12FF) ); // +=
> returns ref. on 'this'.
>
> }
>
> It failed to compile. Because the CPPUNIT_ASSERT_EQUAL must have two
> parameters, like CPPUNIT_ASSERT_EQUAL(expected,actual). Then I changed
> it into CPPUNIT_ASSERT( expectedMoney.getAmount() == money.getAmount()
> ), and it passed.

Thanks, I reported the correction in the doc.

> I want to know whether I could use
> CPPUNIT_ASSERT_EQUAL(expected,actual) to finish my "testAdd"? And
> how? Maybe I didn't really understand the meaning of
> "CPPUNIT_ASSERT_EQUAL( expectedMoney == money.getAmount() )" you
> wrote in your codes, so I hope you can help me:)

No, the usage of CPPUNIT_ASSERT_EQUAL in the tutorial  was a "bug".

The following requirement applied to a type used in CPPUNIT_ASSERT_EQUAL 
(assuming there is no specialization of the template 
CppUnit::assertion_traits<T> for the type):
- it must be comparable with ==
- it must be serializable in a std::ostream (e.g. the function
"std::ostream &operator <<( std::ostream &os, const MyType &value )"
must be defined).

Since Money already have operator ==, the only thing we need to provide is 
std::ostream support:

In Money.h:

#include <iostream>

// at the end of the file:
inline std::ostream &operator <<( std::ostream &os, const Money &value )
{
    return os << "Money< value =" << value.getAmount() << "; currency = " << 
value.getCurrency() << ">";
}

It is now possible to use the CPPUNIT_ASSERT_EQUAL macro:

  CPPUNIT_ASSERT_EQUAL( expectedMoney, money );           // add works

Baptiste.