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// Author: vladl@google.com (Vlad Losev)

// This sample shows how to test code relying on some global flag variables.

// Combine() helps with generating all possible combinations of such flags,

// and each test is given one combination as a parameter.

// Use class definitions to test from this header.

#include "prime_tables.h"

#include "gtest/gtest.h"

#if GTEST_HAS_COMBINE

// Suppose we want to introduce a new, improved implementation of PrimeTable

// which combines speed of PrecalcPrimeTable and versatility of

// OnTheFlyPrimeTable (see prime_tables.h). Inside it instantiates both

// PrecalcPrimeTable and OnTheFlyPrimeTable and uses the one that is more

// appropriate under the circumstances. But in low memory conditions, it can be

// told to instantiate without PrecalcPrimeTable instance at all and use only

// OnTheFlyPrimeTable.

class HybridPrimeTable : public PrimeTable {

 public:

  HybridPrimeTable(bool force_on_the_fly, int max_precalculated)

      : on_the_fly_impl_(new OnTheFlyPrimeTable),

        precalc_impl_(force_on_the_fly ? NULL :

                          new PreCalculatedPrimeTable(max_precalculated)),

        max_precalculated_(max_precalculated) {}

  virtual ~HybridPrimeTable() {

    delete on_the_fly_impl_;

    delete precalc_impl_;

  }

  virtual bool IsPrime(int n) const {

    if (precalc_impl_ != NULL && n < max_precalculated_)

      return precalc_impl_->IsPrime(n);

    else

      return on_the_fly_impl_->IsPrime(n);

  }

  virtual int GetNextPrime(int p) const {

    int next_prime = -1;

    if (precalc_impl_ != NULL && p < max_precalculated_)

      next_prime = precalc_impl_->GetNextPrime(p);

    return next_prime != -1 ? next_prime : on_the_fly_impl_->GetNextPrime(p);

  }

 private:

  OnTheFlyPrimeTable* on_the_fly_impl_;

  PreCalculatedPrimeTable* precalc_impl_;

  int max_precalculated_;

};

using ::testing::TestWithParam;

using ::testing::Bool;

using ::testing::Values;

using ::testing::Combine;

// To test all code paths for HybridPrimeTable we must test it with numbers

// both within and outside PreCalculatedPrimeTable's capacity and also with

// PreCalculatedPrimeTable disabled. We do this by defining fixture which will

// accept different combinations of parameters for instantiating a

// HybridPrimeTable instance.

class PrimeTableTest : public TestWithParam< ::testing::tuple<bool, int> > {

 protected:

  virtual void SetUp() {

    // This can be written as

    //

    // bool force_on_the_fly;

    // int max_precalculated;

    // tie(force_on_the_fly, max_precalculated) = GetParam();

    //

    // once the Google C++ Style Guide allows use of ::std::tr1::tie.

    //

    bool force_on_the_fly = ::testing::get<0>(GetParam());

    int max_precalculated = ::testing::get<1>(GetParam());

    table_ = new HybridPrimeTable(force_on_the_fly, max_precalculated);

  }

  virtual void TearDown() {

    delete table_;

    table_ = NULL;

  }

  HybridPrimeTable* table_;

};

TEST_P(PrimeTableTest, ReturnsFalseForNonPrimes) {

  // Inside the test body, you can refer to the test parameter by GetParam().

  // In this case, the test parameter is a PrimeTable interface pointer which

  // we can use directly.

  // Please note that you can also save it in the fixture's SetUp() method

  // or constructor and use saved copy in the tests.

  EXPECT_FALSE(table_->IsPrime(-5));

  EXPECT_FALSE(table_->IsPrime(0));

  EXPECT_FALSE(table_->IsPrime(1));

  EXPECT_FALSE(table_->IsPrime(4));

  EXPECT_FALSE(table_->IsPrime(6));

  EXPECT_FALSE(table_->IsPrime(100));

}

TEST_P(PrimeTableTest, ReturnsTrueForPrimes) {

  EXPECT_TRUE(table_->IsPrime(2));

  EXPECT_TRUE(table_->IsPrime(3));

  EXPECT_TRUE(table_->IsPrime(5));

  EXPECT_TRUE(table_->IsPrime(7));

  EXPECT_TRUE(table_->IsPrime(11));

  EXPECT_TRUE(table_->IsPrime(131));

}

TEST_P(PrimeTableTest, CanGetNextPrime) {

  EXPECT_EQ(2, table_->GetNextPrime(0));

  EXPECT_EQ(3, table_->GetNextPrime(2));

  EXPECT_EQ(5, table_->GetNextPrime(3));

  EXPECT_EQ(7, table_->GetNextPrime(5));

  EXPECT_EQ(11, table_->GetNextPrime(7));

  EXPECT_EQ(131, table_->GetNextPrime(128));

}

// In order to run value-parameterized tests, you need to instantiate them,

// or bind them to a list of values which will be used as test parameters.

// You can instantiate them in a different translation module, or even

// instantiate them several times.

//

// Here, we instantiate our tests with a list of parameters. We must combine

// all variations of the boolean flag suppressing PrecalcPrimeTable and some

// meaningful values for tests. We choose a small value (1), and a value that

// will put some of the tested numbers beyond the capability of the

// PrecalcPrimeTable instance and some inside it (10). Combine will produce all

// possible combinations.

INSTANTIATE_TEST_CASE_P(MeaningfulTestParameters,

                        PrimeTableTest,

                        Combine(Bool(), Values(1, 10)));

#else

// Google Test may not support Combine() with some compilers. If we

// use conditional compilation to compile out all code referring to

// the gtest_main library, MSVC linker will not link that library at

// all and consequently complain about missing entry point defined in

// that library (fatal error LNK1561: entry point must be

// defined). This dummy test keeps gtest_main linked in.

TEST(DummyTest, CombineIsNotSupportedOnThisPlatform) {}

#endif  // GTEST_HAS_COMBINE