text: // Copyright 2008 Google Inc.
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  // notice, this list of conditions and the following disclaimer.
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  // in the documentation and/or other materials provided with the
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  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  //
  // 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 "gtest/gtest.h"
  #include "prime_tables.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
  