GTEST使用二

接上篇GTEST使用，https://developer.ibm.com/articles/au-googletestingframework/，这个地址介绍的更为简介易懂。

为什么要用GTEST

一些bad内存问题只有在某些运行的时候才会出现。gtest 对此提供了很好的支持。你可以重复很简单的就重复测试100次。当第一次出现的时候，会自动的开启调试调用。只需要命令行中添加这两个选项：–gtest_repeat=1000 --gtest_break_on_failure

gtest内置了assertion

运行case简单，你需要使用使用预定义的宏 RUN_ALL_TESTS。这个是CPPUNIT完全不同的地方，他需要创建一个单独的运行类来进行测试

可以简单的产生一个XML结果，只需要增加 --gtest_output=“xml:”

基础测试

1.一个函数如下：

double square?root (const double);

你可以进行正负数测试

所以有如下case

2.单元测试


#include "gtest/gtest.h"

TEST (SquareRootTest, PositiveNos) { 
    EXPECT_EQ (18.0, square?root (324.0));
    EXPECT_EQ (25.4, square?root (645.16));
    EXPECT_EQ (50.3321, square?root (2533.310224));
}

TEST (SquareRootTest, ZeroAndNegativeNos) { 
    ASSERT_EQ (0.0, square?root (0.0));
    ASSERT_EQ (?1, square?root (?22.0));
}

这个例子创建了一个SquareRootTest的测试，包含了PositiveNos和ZeroAndNegativeNos这两个测试
TEST是gtest.h中预定义的宏。EXPECT_EQ和ASSERT_EQ 同样也是，他俩的区别上篇介绍过，不再赘述。

3.运行 testcase


#include "gtest/gtest.h"

TEST(SquareRootTest, PositiveNos) { 
    EXPECT_EQ (18.0, square?root (324.0));
    EXPECT_EQ (25.4, square?root (645.16));
    EXPECT_EQ (50.3321, square?root (2533.310224));
}

TEST (SquareRootTest, ZeroAndNegativeNos) { 
    ASSERT_EQ (0.0, square?root (0.0));
    ASSERT_EQ (?1, square?root (?22.0));
}

int main(int argc, char ??argv) {
  ::testing::InitGoogleTest(&argc, argv);
  return RUN_ALL_TESTS();
}

::testing::InitGoogleTest 正如名字一样是初始化框架的，必须在RUN_ALL_TESTS前调用
RUN_ALL_TESTS必须只能调用一次，否则会有冲突。RUN_ALL_TESTS会自动的检测所有的TEST的宏。默认情况下，结果打印到标准输出。

4.输出如下：


Running main() from user_main.cpp
[==========] Running 2 tests from 1 test case.
[??????????] Global test environment set?up.
[??????????] 2 tests from SquareRootTest
[ RUN      ] SquareRootTest.PositiveNos
..\user_sqrt.cpp(6862): error: Value of: sqrt (2533.310224)
  Actual: 50.332
Expected: 50.3321
[  FAILED  ] SquareRootTest.PositiveNos (9 ms)
[ RUN      ] SquareRootTest.ZeroAndNegativeNos
[       OK ] SquareRootTest.ZeroAndNegativeNos (0 ms)
[??????????] 2 tests from SquareRootTest (0 ms total)

[??????????] Global test environment tear?down
[==========] 2 tests from 1 test case ran. (10 ms total)
[  PASSED  ] 1 test.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] SquareRootTest.PositiveNos

 1 FAILED TEST

gtest的选项

你可以将输出结果转存到XML中，方式是命令行使用–gtest_output=“xml:report.xml”
函数在某些情况成功某些情况失败，这是内存溢出的典型问题。这种情况在多运行几次的情况下就会出现。 --gtest_repeat=2 --gtest_break_on_failure 如果在命令行中加上这个运行，同样的test会运行2次，并且失败的时候,debugger自动被调用

不是所有的test每次都需要全部运行，如果你执行运行其中的某几个函数，可以使用模糊匹配来做这个。-gtest_filter=* 运行所有的test,–gtest_filter=SquareRoot* 仅运行SquareRootTest 的测试。如果你回想运行SquareRootTest 下的positive的测试，gtest_filter=SquareRootTest.-SquareRootTest.Zero。其中-SquareRootTest.Zero* 表示不运行SquareRootTest下以Zero开头的case

5.一个例子：


[arpan@tintin] ./test_executable ??gtest_output="xml:report.xml" ??gtest_repeat=2 ??
gtest_filter=SquareRootTest.??SquareRootTest.Zero?

Repeating all tests (iteration 1) . . .

Note: Google Test filter = SquareRootTest.??SquareRootTest.Z?
[==========] Running 1 test from 1 test case.
[??????????] Global test environment set?up.
[??????????] 1 test from SquareRootTest
[ RUN      ] SquareRootTest.PositiveNos
..\user_sqrt.cpp (6854): error: Value of: sqrt (2533.310224)
  Actual: 50.332
Expected: 50.3321
[  FAILED  ] SquareRootTest.PositiveNos (2 ms)
[??????????] 1 test from SquareRootTest (2 ms total)

[??????????] Global test environment tear?down
[==========] 1 test from 1 test case ran. (20 ms total)
[  PASSED  ] 0 tests.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] SquareRootTest.PositiveNos
 1 FAILED TEST

Repeating all tests (iteration 2) . . .

Note: Google Test filter = SquareRootTest.??SquareRootTest.Z?
[==========] Running 1 test from 1 test case.
[??????????] Global test environment set?up.
[??????????] 1 test from SquareRootTest
[ RUN      ] SquareRootTest.PositiveNos
..\user_sqrt.cpp (6854): error: Value of: sqrt (2533.310224)
  Actual: 50.332
Expected: 50.3321
[  FAILED  ] SquareRootTest.PositiveNos (2 ms)
[??????????] 1 test from SquareRootTest (2 ms total)

[??????????] Global test environment tear?down
[==========] 1 test from 1 test case ran. (20 ms total)
[  PASSED  ] 0 tests.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] SquareRootTest.PositiveNos
 1 FAILED TEST

暂时停用某些tests

6.用DISABLE_后缀暂时停用一个case


#include "gtest/gtest.h"

TEST (DISABLED_SquareRootTest, PositiveNos) { 
    EXPECT_EQ (18.0, square?root (324.0));
    EXPECT_EQ (25.4, square?root (645.16));
    EXPECT_EQ (50.3321, square?root (2533.310224));
}

OR

TEST (SquareRootTest, DISABLED_PositiveNos) { 
    EXPECT_EQ (18.0, square?root (324.0));
    EXPECT_EQ (25.4, square?root (645.16));
    EXPECT_EQ (50.3321, square?root (2533.310224));
}

7.包含DISABLE的示例输出如下


1 FAILED TEST
  YOU HAVE 1 DISABLED TEST

用在命令行输入：gtest_also_run_disabled_tests 选项可以执行DISABLE的case，输出如下：

8.输出


[??????????] 1 test from DISABLED_SquareRootTest
[ RUN      ] DISABLED_SquareRootTest.PositiveNos
..\user_sqrt.cpp(6854): error: Value of: square?root (2533.310224)
  Actual: 50.332
Expected: 50.3321
[  FAILED  ] DISABLED_SquareRootTest.PositiveNos (2 ms)
[??????????] 1 test from DISABLED_SquareRootTest (2 ms total)

[  FAILED  ] 1 tests, listed below:
[  FAILED  ] SquareRootTest. PositiveNos

浮点型数据比较

9.用于比较浮点数的宏


ASSERT_FLOAT_EQ (expected, actual)
ASSERT_DOUBLE_EQ (expected, actual) 
ASSERT_NEAR (expected, actual, absolute_range)

EXPECT_FLOAT_EQ (expected, actual)
EXPECT_DOUBLE_EQ (expected, actual) 
EXPECT_NEAR (expected, actual, absolute_range)

通常由于浮点数的在各不同CPU下和操作系统下，一个简单的的相等无法生效。比如ASSERT_FLOAT_EQ (2.00001, 2.000011) 可以通过。如果想要高精度的，需要ASSERT_NEAR (2.00001, 2.000011, 0.0000001) ，输出如下：

ASSERT_NEAR的输出


Math.cc(68): error: The difference between 2.00001 and 2.000011 is 1e?006, which exceeds
0.0000001, where
2.00001 evaluates to 2.00001,
2.000011 evaluates to 2.00001, and
0.0000001 evaluates to 1e?007.

death test

ASSERT_DEATH, ASSERT_EXIT等等

10.death test示例


#include "gtest/gtest.h"

double square?root (double num) { 
    if (num < 0.0) { 
        std::cerr << "Error: Negative Input\n";
        exit(?1);
    }
    // Code for 0 and +ve numbers follow

}

TEST (SquareRootTest, ZeroAndNegativeNos) { 
    ASSERT_EQ (0.0, square?root (0.0));
    ASSERT_EXIT (square?root (?22.0), ::testing::ExitedWithCode(?1), "Error: 
Negative Input");
}

int main(int argc, char ??argv) {
  ::testing::InitGoogleTest(&argc, argv);
  return RUN_ALL_TESTS();
}

12.death test的原型


ASSERT_DEATH(statement, expected_message)
ASSERT_EXIT(statement, predicate, expected_message)

test fixtures

13.一个fixture示例

典型场景，在单元测试前，做一些个性化的初始化。比如你做一些时间和内存的占用测试，你就需要一些特定的代码来做这些测试


class myTestFixture1: public ::testing::Test { 
public: 
   myTestFixture1( ) { 
       // initialization code here
   } 

   void SetUp( ) { 
       // code here will execute just before the test ensues 
   }

   void TearDown( ) { 
       // code here will be called just after the test completes
       // ok to through exceptions from here if need be
   }

   ~myTestFixture1( )  { 
       // cleanup any pending stuff, but no exceptions allowed
   }

   // put in any custom data members that you need 
};

text fixture的场景要使用TEST_F代替TEST，下面是一个简单的例子

14.一个简单的fixture用例


TEST_F (myTestFixture1, UnitTest1) { 
   
.
}

TEST_F (myTestFixture1, UnitTest2) { 
   
.
}

下面有几点需要注意：

初始化可以放在构造，也可以放在SetUp，取决于用户。
析构资源放在析构函数，还是TearDown也都可以。但是如果释放资源的的时候，需要处理异常的情况，你必须放在TearDwon，因为析构中throw Exception是未定义行为
assertion的宏也可能会throw 异常，所以为了更好的维护性，assertion的宏也可以放在TearDwon中
通安一个的test fixture不会在多个case中使用，每一次测试会创建一个新的test fixture。比如14中的测试，SetUp会被调用两次，因为myFixture1 对象会被创建两次