UnitTests with mocked local objects

[ChiliPalmer]

Hi everyone,

for our UnitTests we use QTest and additionally Google Mock, but I struggle to decide how to write tests for methods which use local objects.

Say I have this method:

void foo::bar() {
  SomeObject object;
  object.load(member1);
  object.doSomething(member2, member3);
  useObject(object);
}

void foo::bar() {
  SomeObject object;
  object.load(member1);
  object.doSomething(member2, member3);
  useObject(object);
}

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Now, to be able to test certain things I would like to use a MockSomeObject instead of SomeObject. One way to do that would look something like this:

void foo::bar() {
  QScopedPointer<SomeObject> object(SomeObjectFactory::singletonPtr()->instance(member1));
  object->doSomething(member2, member3);
  useObject(object);
}

void foo::bar() {
  QScopedPointer<SomeObject> object(SomeObjectFactory::singletonPtr()->instance(member1));
  object->doSomething(member2, member3);
  useObject(object);
}

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In my test I would just replace SomeObjectFactory with MockSomeObjectFactory, which would create MockSomeObject.

Another way would look like this:

void foo::bar() {
  SomeObject object;
  object.load(member1);
  bar(object);
}
 
void foo::bar(SomeObject& object) {
  object.doSomething(member2, member3);
  useObject(object);
}

void foo::bar() {
  SomeObject object;
  object.load(member1);
  bar(object);
}

void foo::bar(SomeObject& object) {
  object.doSomething(member2, member3);
  useObject(object);
}

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I discussed this with a colleague, and we would really appreciate other opinions or other possibilities.