Google C++ Testing Framework in Visual Studio 2008

Using Google Test with Visual Studio 2008 Andrea Francia (Galileian Plus) XPUG (14 aprile 2010) http:// www.galileianplus.it / http:// www.andreafrancia.it / http://blog.andreafrancia.it/

SISMA Project

GOCE-Italy

Contents
Basics of C program compilation
How many C++ testing framework are out there?
Introduction to Google C++ Testing Framework (aka gtest)
How to download/compile/link/use gtest (live)
(Maybe) Some usage examples

Hello World Example // file: hello.c #include <stdio.h> int main( int argc, char * argv[]) { printf( "Hello World " ); }

Steps in C compilation C Preprocessor C Compiler Linker a.out (.exe) hello.c stdio.h hello.i hello.o (.obj) libc.a (.lib) where printf is declared where printf is defined (from /usr/lib/) (from /usr/include)

Which testing framework?
According to Wikipedia [1] we have 42 framework for C++ !!
For comparison:
# of choices for C++: 42
# of choices for Java: 23
# of choices for .Net: 21
# of choices for Objective-C: 5
# of choices for C: 32
[1] http://en.wikipedia.org/wiki/List_of_unit_testing_frameworks#C.2B.2B

Narrowing selection
The test frameworks chosen:
CppUnit
CppUnitLite
Google C++ Testing Framework

CppUnit
Features:
 Created by Michael Feathers [1]
 Opensource
 API similar to JUnit
 The JUnit-like API doesn’t match the C++ features  longer fixtures
 Michael Feathers don’t use it anymore!
[1] The author of “Working Effectively with Legacy Code”

CppUnitLite
Features:
 Also created by Michael Feathers [1]
 Opensource
 Exploits the features of the language(s)
 => More easily write individual tests
 Michael Feathers still use it.
[1] He decided that using CppUnit was too elaborate!

Features:
Written by some guys at Google
 Writing test seems as simple as in CppUnitLite
 Opensource
 Works on many platforms:
Visual Studio
XCode
gcc
  Documentation available online
  Seems to be used by many people (at least on stackoverflow.com)

The Winner is
Google C ++ Testing Framework
(a.k.a. gtest)

What do you need?
Visual Studio 2008
Google Test Package (gtest-1.4.0.zip)
This guide 

How test are defined
// the_compiler.cc
#include <gtest/gtest.h>
TEST( the_compiler , is_able_to_add ) {
ASSERT_EQ(2, 1+1);
}
TEST( the_compiler , knows_when_two_numbers_are_different ) {
ASSERT_NE(1, 2);
}
TEST( the_compiler , knows_who_comes_first ) {
ASSERT_LT(1, 2);
ASSERT_GT(2, 1);
}
Suggested nomeclature: A. The system under test. B. The tested features. Note: Autodiscovery! No need of enumerating tests. 1. Include the library headers 2. Write a TEST() for each features 2.1. Write Assertions

The Output Window

The Optional main() function
Maybe you would insert a main() function which exercise all the test:
int main( int argc, char * argv[]) {
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}
Or you can simply add this lib: gtest_maind.lib

How To Set Up (live) 1/2
Download and unzip gtest-1.4.0.zip
(from http:// code.google.com/p/googletest / )
Build solution gtest-1.4.0/msvc/gtest.sln
Create your testing project
Add this to include path:
gtest 1.4.0/includes
Add these to the library path:
gtest 1.4.0msvcgtestDebuggtest_maind.lib
gtest-1.4.0msvcgtestDebuggtestd.lib

How To Set Up (live) 2/2
Resolve the remaining errors with some magic:
Resolve linking error with:
Use the “Multi-threaded Debug (/MTd)” option
Resolve the manifest error with:
A “clean and build” !
Make FAIL messages clickable with:
Setting
Build Events > Post-Build Event > Command Line
To value:
"$(TargetDir)$(TargetFileName)"

Assertions
Most used assertion:
ASSERT_TRUE( condition );
ASSERT_FALSE( condition );
ASSERT_EQ( expected, actual );
ASSERT_NE( val1, val2 );
ASSERT_STREQ( expected_str , actual_str );

Expectations
Most used expectations:
EXPECT_TRUE( condition );
EXPECT_FALSE( condition );
EXPECT_EQ( expected, actual );
EXPECT_NE( val1, val2 );
EXPECT_STREQ( expected_str , actual_str );
Expectations vs Assertions:
If an assertion fails the TEST execution stops
If an expectation fails the TEST execution continues

References
Feathers, Michael C (2004).
Working Effectively with Legacy Code.
Prentice Hall. ISBN 0-13-117705-2 .
Exploring the C++ Unit Testing Framework Jungle
http://gamesfromwithin.com/exploring-the-c-unit-testing-framework-jungle
Compiler, Assembler, Linker and Loader: a brief story:
http://www.tenouk.com/ModuleW.html (spiega pure il formato ELF!)
http:// code.google.com/p/googletest /
Tutorial Google Test con Visual Studio 2008
http://blog.andreafrancia.it/2010/04/tutorial-google-test_01.html

Grazie dell’ascolto!
(soprattutto alla mia fidanzata ;)

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Google C++ Testing Framework in Visual Studio 2008

by Andrea Francia

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