googletest：sample7分析

目录

googletest：sample1
googletest：sample2
googletest：sample3
googletest：sample4
googletest：sample5
googletest：sample6
googletest：sample7
googletest：sample8
googletest：sample9

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

sample6的测试，类型参数化测试，利用"typed test" "type-parameterized tests" 2种方法复用test，对不同类型的派生类进行测试.

sample7的测试，接口测试，利用"value-parameterized tests" 复用test，测试接口的多个实现的公共属性.

步骤：
1）利用工厂方法CreateOnTheFlyPrimeTable, CreatePreCalculatedPrimeTable创建待测对象；
2）利用夹具类的Setup(),TearDown()负责待测对象的创建、销毁；
3）利用TEST_P()定义test；
4）利用INSTANTIATE_TEST_SUITE_P初始化作为测试参数的值列表.

---

tips: TEST_P(test_suite_name, test_name)定义一个test，test_suite_name必须匹配测试夹具名，test_name是自定义test名称.

---

// This sample shows how to test common properties of multiple
// implementations of an interface (aka interface tests) using
// value-parameterized tests. Each test in the test case has
// a parameter that is an interface pointer to an implementation
// tested.

// The interface and its implementations are in this header.
#include "prime_tables.h"
#include "gtest/gtest.h"
namespace {

using ::testing::TestWithParam;
using ::testing::Values;

// As a general rule, to prevent a test from affecting the tests that come
// after it, you should create and destroy the tested objects for each test
// instead of reusing them.  In this sample we will define a simple factory
// function for PrimeTable objects.  We will instantiate objects in test's
// SetUp() method and delete them in TearDown() method.
typedef PrimeTable* CreatePrimeTableFunc();

PrimeTable* CreateOnTheFlyPrimeTable() { return new OnTheFlyPrimeTable(); }

template <size_t max_precalculated>
PrimeTable* CreatePreCalculatedPrimeTable() {
  return new PreCalculatedPrimeTable(max_precalculated);
}

// Inside the test body, fixture constructor, SetUp(), and TearDown() you
// can refer to the test parameter by GetParam().  In this case, the test
// parameter is a factory function which we call in fixture's SetUp() to
// create and store an instance of PrimeTable.
class PrimeTableTestSmpl7 : public TestWithParam<CreatePrimeTableFunc*> {
 public:
  ~PrimeTableTestSmpl7() override { delete table_; }
  void SetUp() override { table_ = (*GetParam())(); }
  void TearDown() override {
    delete table_;
    table_ = nullptr;
  }

 protected:
  PrimeTable* table_;
};

TEST_P(PrimeTableTestSmpl7, ReturnsFalseForNonPrimes) {
  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(PrimeTableTestSmpl7, 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(PrimeTableTestSmpl7, 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 two PrimeTable object
// factory functions:
INSTANTIATE_TEST_SUITE_P(OnTheFlyAndPreCalculated, PrimeTableTestSmpl7,
                         Values(&CreateOnTheFlyPrimeTable,
                                &CreatePreCalculatedPrimeTable<1000>));

}  // namespace

用宏INSTANTIATE_TEST_SUITE_P + Values 实例化包含一个包含2个PrimeTable对象工厂方法的列表，GTest就会进行value-parameterized tests，为每个参数实例化test；

INSTANTIATE_TEST_SUITE_P(prefix, test_suite_name, ...)实例化一个test suite，"prefix"是test_suite_name的前缀名，"test_suite_name"是组件名，"..."包含了要用作test parameters的值列表.

而在Test, Test Fixture的ctor, Setup(), TearDown()中，可通过GetParam()获取列表中的参数.

小结

3个宏TEST, TEST_F, TEST_P, TYPED_TEST区别：

• TEST

用于创建最简单的test，定义一个测试函数，在其中可定义任何C++代码并用gtest提供的断言进行检查. 不需要继承任何类.

语法：

TEST(test_suite_name, test_name)

其中，test_suite_name 测试组件名，test_name 测试名.

示例：sample1, sample2, sample4

• TEST_F

用于创建需要共享测试对象的test，需要搭配自定义test fixture（测试夹具，继承自testing::Test）类使用，用virtual Setup(), TearDown()管理测试对象执行test前的初始化、执行后的清理工作.

TEST_F(test_fixture, test_name)

其中，test_fixture 测试夹具名，test_name 测试名.

示例：sample3, sample5

• TEST_P

用于参数化test. 允许开发者为同一个test提供多个参数，自动为每个参数生成一个单独的test. 通过INSTANTIATE_TEST_SUITE_P指定数据集，GTest自动为每个数据在运行时生成相应的test并执行.

TEST_P(test_suite_name, test_name)

其中，test_suite_name 测试组件名，需匹配测试夹具名，test_name测试名.

示例：sample7

• TYPED_TEST

用于类型化test，针对多种类型需要复用同一test的情形. 基于C++模板实现.

TYPED_TEST(CaseName, TestName)

其中，CaseName 用例名，需要匹配测试夹具名，TestName 测试名.

示例：sample6

参考

gtest中TEST和TEST_F和TEST_P的区别是什么

【C++ 单元测试】 GTest 指南：剖析 TEST_P 与 TYPED_TEST