目录
- 待测文件
- 测试文件
待测文件
同sample6，都是prime_tables.h文件
PrimeTable类声明了素数表的一系列接口，包括
1）IsPrime：判断当前输入数n是否为素数；
2）GetNextPrime：找比输入数n大的下一个素数.
文件内容略.
测试文件
如果我们想引进一种新的、改进的PrimeTable实现，结合了PrecalcPrimeTable的速度和OnTheFlyPrimeTable的多功能特性，用于判断一个数是否素数、获取下一个素数. 在内部，实例化了PrecalcPrimeTable, OnTheFlyPrimeTable，在特定情况下只使用更适合的一个. 但在内存不足时，可以在不实例化PreCalculatedPrimeTable的情况下实例化HybridPrimeTable，并且只使用OnTheFlyPrimeTable.
sample8_unittest.cc
// 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? nullptr: new PreCalculatedPrimeTable(max_precalculated)),max_precalculated_(max_precalculated) {}~HybridPrimeTable() override {delete on_the_fly_impl_;delete precalc_impl_;}bool IsPrime(int n) const override {if (precalc_impl_ != nullptr && n < max_precalculated_)return precalc_impl_->IsPrime(n);elsereturn on_the_fly_impl_->IsPrime(n);}int GetNextPrime(int p) const override {int next_prime = -1;if (precalc_impl_ != nullptr && 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::Bool;
using ::testing::Combine;
using ::testing::TestWithParam;
using ::testing::Values;// 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< ::std::tuple<bool, int> > {protected:void SetUp() override {bool force_on_the_fly;int max_precalculated;std::tie(force_on_the_fly, max_precalculated) = GetParam();table_ = new HybridPrimeTable(force_on_the_fly, max_precalculated);}void TearDown() override {delete table_;table_ = nullptr;}HybridPrimeTable* table_;
};
通过testing::TestWithParam<>的模板参数，将是否需要强制使用OnTheFlyPrimeTable (bool)和PreCalculatedPrimeTable (int)表中最大数 传递给PrimeTableTest，进而决定如何实例化HybridPrimeTable.
如何设计test？
跟普通的TEST类似依然可以用HybridPrimeTable提供接口进行测试.
当然，还能在test body中，通过GetParam()获取由INSTANTIATE_TEST_SUITE_P实例化的test parameter.
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));
}
设计完test，还需要用宏INSTANTIATE_TEST_SUITE_P来实例化"value-parameterized tests"，GoogleTest才会针对每个实例进行test.
// 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_SUITE_P(MeaningfulTestParameters, PrimeTableTest,Combine(Bool(), Values(1, 10)));
注意：这里INSTANTIATE_TEST_SUITE_P第三个参数Combine(Bool(), Values(1, 10))对应的是TestWithParam< ::std::tuple<bool, int> >的模板参数，而sample7对应传的参数是Values(&CreateOnTheFlyPrimeTable, &CreatePreCalculatedPrimeTable<1000>)，即工厂方法的函数地址. 而我们用GetParam()获取的，就是这里的第三个参数.
