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      1 // Copyright 2008 Google Inc.
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     28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29 //
     30 // Author: vladl (at) google.com (Vlad Losev)
     31 
     32 // This sample shows how to test code relying on some global flag variables.
     33 // Combine() helps with generating all possible combinations of such flags,
     34 // and each test is given one combination as a parameter.
     35 
     36 // Use class definitions to test from this header.
     37 #include "prime_tables.h"
     38 
     39 #include <gtest/gtest.h>
     40 
     41 #if GTEST_HAS_COMBINE
     42 
     43 // Suppose we want to introduce a new, improved implementation of PrimeTable
     44 // which combines speed of PrecalcPrimeTable and versatility of
     45 // OnTheFlyPrimeTable (see prime_tables.h). Inside it instantiates both
     46 // PrecalcPrimeTable and OnTheFlyPrimeTable and uses the one that is more
     47 // appropriate under the circumstances. But in low memory conditions, it can be
     48 // told to instantiate without PrecalcPrimeTable instance at all and use only
     49 // OnTheFlyPrimeTable.
     50 class HybridPrimeTable : public PrimeTable {
     51  public:
     52   HybridPrimeTable(bool force_on_the_fly, int max_precalculated)
     53       : on_the_fly_impl_(new OnTheFlyPrimeTable),
     54         precalc_impl_(force_on_the_fly ? NULL :
     55                           new PreCalculatedPrimeTable(max_precalculated)),
     56         max_precalculated_(max_precalculated) {}
     57   virtual ~HybridPrimeTable() {
     58     delete on_the_fly_impl_;
     59     delete precalc_impl_;
     60   }
     61 
     62   virtual bool IsPrime(int n) const {
     63     if (precalc_impl_ != NULL && n < max_precalculated_)
     64       return precalc_impl_->IsPrime(n);
     65     else
     66       return on_the_fly_impl_->IsPrime(n);
     67   }
     68 
     69   virtual int GetNextPrime(int p) const {
     70     int next_prime = -1;
     71     if (precalc_impl_ != NULL && p < max_precalculated_)
     72       next_prime = precalc_impl_->GetNextPrime(p);
     73 
     74     return next_prime != -1 ? next_prime : on_the_fly_impl_->GetNextPrime(p);
     75   }
     76 
     77  private:
     78   OnTheFlyPrimeTable* on_the_fly_impl_;
     79   PreCalculatedPrimeTable* precalc_impl_;
     80   int max_precalculated_;
     81 };
     82 
     83 using ::testing::TestWithParam;
     84 using ::testing::Bool;
     85 using ::testing::Values;
     86 using ::testing::Combine;
     87 
     88 // To test all code paths for HybridPrimeTable we must test it with numbers
     89 // both within and outside PreCalculatedPrimeTable's capacity and also with
     90 // PreCalculatedPrimeTable disabled. We do this by defining fixture which will
     91 // accept different combinations of parameters for instantiating a
     92 // HybridPrimeTable instance.
     93 class PrimeTableTest : public TestWithParam< ::std::tr1::tuple<bool, int> > {
     94  protected:
     95   virtual void SetUp() {
     96     // This can be written as
     97     //
     98     // bool force_on_the_fly;
     99     // int max_precalculated;
    100     // tie(force_on_the_fly, max_precalculated) = GetParam();
    101     //
    102     // once the Google C++ Style Guide allows use of ::std::tr1::tie.
    103     //
    104     bool force_on_the_fly = ::std::tr1::get<0>(GetParam());
    105     int max_precalculated = ::std::tr1::get<1>(GetParam());
    106     table_ = new HybridPrimeTable(force_on_the_fly, max_precalculated);
    107   }
    108   virtual void TearDown() {
    109     delete table_;
    110     table_ = NULL;
    111   }
    112   HybridPrimeTable* table_;
    113 };
    114 
    115 TEST_P(PrimeTableTest, ReturnsFalseForNonPrimes) {
    116   // Inside the test body, you can refer to the test parameter by GetParam().
    117   // In this case, the test parameter is a PrimeTable interface pointer which
    118   // we can use directly.
    119   // Please note that you can also save it in the fixture's SetUp() method
    120   // or constructor and use saved copy in the tests.
    121 
    122   EXPECT_FALSE(table_->IsPrime(-5));
    123   EXPECT_FALSE(table_->IsPrime(0));
    124   EXPECT_FALSE(table_->IsPrime(1));
    125   EXPECT_FALSE(table_->IsPrime(4));
    126   EXPECT_FALSE(table_->IsPrime(6));
    127   EXPECT_FALSE(table_->IsPrime(100));
    128 }
    129 
    130 TEST_P(PrimeTableTest, ReturnsTrueForPrimes) {
    131   EXPECT_TRUE(table_->IsPrime(2));
    132   EXPECT_TRUE(table_->IsPrime(3));
    133   EXPECT_TRUE(table_->IsPrime(5));
    134   EXPECT_TRUE(table_->IsPrime(7));
    135   EXPECT_TRUE(table_->IsPrime(11));
    136   EXPECT_TRUE(table_->IsPrime(131));
    137 }
    138 
    139 TEST_P(PrimeTableTest, CanGetNextPrime) {
    140   EXPECT_EQ(2, table_->GetNextPrime(0));
    141   EXPECT_EQ(3, table_->GetNextPrime(2));
    142   EXPECT_EQ(5, table_->GetNextPrime(3));
    143   EXPECT_EQ(7, table_->GetNextPrime(5));
    144   EXPECT_EQ(11, table_->GetNextPrime(7));
    145   EXPECT_EQ(131, table_->GetNextPrime(128));
    146 }
    147 
    148 // In order to run value-parameterized tests, you need to instantiate them,
    149 // or bind them to a list of values which will be used as test parameters.
    150 // You can instantiate them in a different translation module, or even
    151 // instantiate them several times.
    152 //
    153 // Here, we instantiate our tests with a list of parameters. We must combine
    154 // all variations of the boolean flag suppressing PrecalcPrimeTable and some
    155 // meaningful values for tests. We choose a small value (1), and a value that
    156 // will put some of the tested numbers beyond the capability of the
    157 // PrecalcPrimeTable instance and some inside it (10). Combine will produce all
    158 // possible combinations.
    159 INSTANTIATE_TEST_CASE_P(MeaningfulTestParameters,
    160                         PrimeTableTest,
    161                         Combine(Bool(), Values(1, 10)));
    162 
    163 #else
    164 
    165 // Google Test doesn't support Combine() on some platforms and compilers,
    166 // such as MSVC 7.1. If we use conditional compilation to compile out
    167 // all code referring to the gtest_main library, MSVC linker will not
    168 // link that library at all and consequently complain about missing entry
    169 // point defined in that library (fatal error LNK1561: entry point must
    170 // be defined). This dummy test keeps gtest_main linked in.
    171 TEST(DummyTest, CombineIsNotSupportedOnThisPlatform) {}
    172 
    173 #endif  // GTEST_HAS_COMBINE
    174