Google Testing Blog: TotT: Keep Your Fakes Simple

TotT: Keep Your Fakes Simple

Thursday, January 22, 2009

TEST_F(BabyCondorTest, EatsCarrion) {
  FakeCondor mother;
  scoped_ptr carrion;
  BabyCondor* pchick = &chick_;
  mother.Imprint(vector(&pchick, &pchick + 1)); // just one chick
  while(!chick_.HasFood()) {
    mother.Eat(); // disposes of any food the mother kept for herself
    mother.Scavenge(carrion.reset(new FakeCarrion)); // finds new food
    mother.RandomlyDistributeFoodAmongYoungAndSelf(); // feeds baby or mom
  }
  chick_.Eat();
  EXPECT_TRUE(carrion->WasEaten());
}a lot of setup!replicates too much functionalityextracting a role interface class CondorMotherhoodRoleInterface {
public:
  virtual Carrion* GiveFood() = 0;
  virtual SomeReturnTypes* OtherMomBehaviors() = 0;
};single-use fakeonly behaviors we need for this particular test class CondorFeedingPuppet: public CondorMotherhoodRoleInterface {
public:
  virtual Carrion* GiveFood() { return test_carrion_; }
  virtual SomeReturnTypes* OtherMomBehaviors() { return NULL; }
  Carrion* test_carrion_; // public var is tolerable in a one-off object
};

TEST_F(BabyCondorTest, EatsCarrion) {
  CondorFeedingPuppet mother; FakeCarrion test_carrion;
  mother.test_carrion_ = &test_carrion;
  chick_.ReceiveFood(&mother);
  chick_.Eat();
  EXPECT_TRUE(test_carrion.WasEaten());
}highly-focused fakeeasy and quick to writesimplermore readablethis episode