Qt: How to organize Unit Test with more than one class?

As per the solution you linked to, the way to accomplish testing two (or more) classes within a single Qt unit test project is to ensure that each class to be tested has a corresponding test class, and that you've created a custom int main that executes each test class.

For example:

class TestClassA : public QObject
{
   Q_OBJECT
public:
   TestClassA();

   ...

private Q_SLOTS:
   void testCase1();
   ...
};

class TestClassB : public QObject
{
   Q_OBJECT
public:
   TestClassB();

   ...

private Q_SLOTS:
   void testCase2();
   ...
};

void TestClassA::testCase1()
{
   // Define test here.
}

void TestClassB::testCase2()
{
   // Define test here.
}

// Additional tests defined here.

// Note: This is equivalent to QTEST_APPLESS_MAIN for multiple test classes.
int main(int argc, char** argv)
{
   int status = 0;
   {
      TestClassA tc;
      status |= QTest::qExec(&tc, argc, argv);
   }
   {
      TestClassB tc;
      status |= QTest::qExec(&tc, argc, argv);
   }
   return status;
}

Obviously, the different test classes can be spread out over multiple translation units, then simply included in the translation unit with your int main. Don't forget to include the appropriate .moc files.

Based in the accepted answer and if you are using C++11 you could be interested in a solution using lambdas. It avoids you write the same code everytime. Although you can replace the lambda with a function, I think a lambda is cleaner.

#include <QtTest>

#include "test1.h"
#include "test2.h"


int main(int argc, char** argv)
{
   int status = 0;
   auto ASSERT_TEST = [&status, argc, argv](QObject* obj) {
     status |= QTest::qExec(obj, argc, argv);
     delete obj;
   };

   ASSERT_TEST(new Test1());
   ASSERT_TEST(new Test2());

   return status;
}

#ifndef TEST1_H
#define TEST1_H

Sample test

#include <QtTest>

class Test1 : public QObject
{
    Q_OBJECT

  private Q_SLOTS:
    void testCase1();
};

Searching for this same answer, I found a very good solution from http://qtcreator.blogspot.de/2009/10/running-multiple-unit-tests.html. He creates a namespace with a container that registers all the tests created (via the DECLARE_TEST macro), and then uses it to run all the tests on the list. I rewrote it to fit my code and I post my version here (My Qt Creator version: 4.1.0):

/* BASED ON
 * http://qtcreator.blogspot.de/2009/10/running-multiple-unit-tests.html
 */    
#ifndef TESTCOLLECTOR_H
#define TESTCOLLECTOR_H

#include <QtTest>
#include <memory>
#include <map>
#include <string>

namespace TestCollector{
typedef std::map<std::string, std::shared_ptr<QObject> > TestList;
inline TestList& GetTestList()
{
   static TestList list;
   return list;
}

inline int RunAllTests(int argc, char **argv) {
    int result = 0;
    for (const auto&i:GetTestList()) {
        result += QTest::qExec(i.second.get(), argc, argv);
    }
    return result;
}

template <class T>
class UnitTestClass {
public:
    UnitTestClass(const std::string& pTestName) {
        auto& testList = TestCollector::GetTestList();
        if (0==testList.count(pTestName)) {
            testList.insert(std::make_pair(pTestName, std::make_shared<T>()));
        }
    }
};
}

#define ADD_TEST(className) static TestCollector::UnitTestClass<className> \
    test(#className);

#endif // TESTCOLLECTOR_H

Then, just add the ADD_TEST(class) line in your test header like this:

#ifndef TESTRANDOMENGINES_H
#define TESTRANDOMENGINES_H

#include <QtTest>
#include "TestCollector.h"

class TestRandomEngines : public QObject
{
    Q_OBJECT

private Q_SLOTS:
    void test1();
};

ADD_TEST(TestRandomEngines)

#endif // TESTRANDOMENGINES_H

And and to run all the tests, just do:

#include "TestCollector.h"
#include <iostream>

int main(int argc, char *argv[]) {
    auto nFailedTests = TestCollector::RunAllTests(argc, argv);
    std::cout << "Total number of failed tests: "
              << nFailedTests << std::endl;
    return nFailedTests;
}