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引言

前文我们已经讲解了gmock的基本语法，但是gmock只能mock虚函数，如果要mock非虚成员函数、静态成员函数、全局函数、重载函数、模板函数以及其他依赖库的函数时，gmock就很难实现。而cppmockfree可以支持这些函数的mock。

快速入门

1. mock样例

1.1 全局函数

// gloabal function
int g_func(int a, int b)
{return a + b;
}

#include "gtest/gtest.h"
#include "gmock/gmock.h"
#include "cpp_free_mock.h"
#include <string>using namespace ::testing;
using namespace ::CppFreeMock;namespace {
TEST(TestCppMockFree, CaseGlobalFunction) 
{auto mock = MOCKER(g_func);EXPECT_CALL(*mock, MOCK_FUNCTION(_, _)).WillOnce(Return(1)).WillRepeatedly(Return(2));EXPECT_EQ(1, g_func(1, 2));EXPECT_EQ(2, g_func(12, 2));mock->RestoreToReal();EXPECT_EQ(14, g_func(12, 2));
}

1.2 成员函数

class Adder {
public:int add(int a, int b) const{return a + b;}
};

TEST(TestCppMockFree, CaseStaticMemberFunction) 
{auto mock = MOCKER(&Adder::add);// 针对类的成员函数，要注意占位符会多出一个，即第一个为this指针// 而全局函数或者静态成员函数占位符个数等于实际参数个数EXPECT_CALL(*mock, MOCK_FUNCTION(_, _, _)).WillRepeatedly(Return(2));Adder adder;EXPECT_EQ(2, adder.add(1, 2));EXPECT_EQ(2, adder.add(12, 2));mock->RestoreToReal();EXPECT_EQ(14, g_func(12, 2));
}

1.3 静态成员函数

// static member function
class Printer {
public:static std::string print(const std::string& str){return str;}
};

TEST(TestCppMockFree, CaseStaticMemberFunction) 
{auto mock = MOCKER(Printer::print);EXPECT_CALL(*mock, MOCK_FUNCTION(_)).WillRepeatedly(Return(std::string("mocker")));EXPECT_STREQ("mocker", Printer::print("hello").c_str());mock->RestoreToReal();EXPECT_STREQ("hello", Printer::print("hello").c_str());
}

1.4 函数重载

// overload function
class OverloadFunc {
public:int foo() { return 0; }int foo(int a) { return a;}
};

TEST(TestCppMockFree, CaseOverloadFunction) 
{OverloadFunc overload_func;typedef int (OverloadFunc::*FuncType0)();typedef int (OverloadFunc::*FuncType1)(int);auto mock0 = MOCKER((FuncType0)&OverloadFunc::foo);EXPECT_CALL(*mock0, MOCK_FUNCTION(_)).WillRepeatedly(Return(2));EXPECT_EQ(2, overload_func.foo());auto mock1 = MOCKER((FuncType1)&OverloadFunc::foo);EXPECT_CALL(*mock1, MOCK_FUNCTION(_,  _)).WillRepeatedly(Return(2));EXPECT_EQ(2, overload_func.foo(1));mock0->RestoreToReal();mock1->RestoreToReal();EXPECT_EQ(2, overload_func.foo(1));mock0->RestoreToReal();mock1->RestoreToReal();EXPECT_EQ(0, overload_func.foo());EXPECT_EQ(1, overload_func.foo(1));
}

1.5 模板类成员函数

// template class
template <class T>
class AdderT {
public:T add(T a, T b) { return a + b; }T add(T a, T b, T c) { return a + b + c; }T adder(T a) { return a; }
};

TEST(TestCppMockFree, CaseTemplateFunction) 
{AdderT<int> adder;// overload functiontypedef int (AdderT<int>::*FuncType0)(int, int);auto mock0 = MOCKER((FuncType0)&AdderT<int>::add);EXPECT_CALL(*mock0, MOCK_FUNCTION(_, _, _)).WillRepeatedly(Return(1));EXPECT_EQ(1, adder.add(1, 2));auto mock1 = MOCKER((FuncType1)&AdderT<int>::add);EXPECT_CALL(*mock1, MOCK_FUNCTION(_, _, _, _)).WillRepeatedly(Return(1));EXPECT_EQ(1, adder.add(1, 2));auto mock1 = MOCKER((FuncType1)&AdderT<int>::add);EXPECT_CALL(*mock1, MOCK_FUNCTION(_, _, _, _)).WillRepeatedly(Return(1));EXPECT_EQ(1, adder.add(1, 2, 3));mock0->RestoreToReal();mock1->RestoreToReal();EXPECT_EQ(3, adder.add(1, 2));EXPECT_EQ(6, adder.add(1, 2, 3));// normal functionauto mock2 = MOCKER(&AdderT<int>::adder);EXPECT_CALL(*mock2, MOCK_FUNCTION(_, _)).WillRepeatedly(Return(1));EXPECT_EQ(1, adder.adder(2));mock2->RestoreToReal();EXPECT_EQ(2, adder.adder(2));
}

1.6 外部库函数

TEST(TestCppMockFree, CaseOtherLibrary)
{auto mock = MOCKER(std::atoi);EXPECT_CALL(*mock, MOCK_FUNCTION(_)).WillRepeatedly(Return(22867));EXPECT_EQ(22867, std::atoi("123"));mock->RestoreToReal();EXPECT_EQ(123, std::atoi("123"));
} 

2. 引入cppmockfree

git clone https://github.com/gzc9047/CppFreeMock.git

注意在引入cppmockfree之前请务必引入gtest和gmock。如何引入，在我之前的文章中均有提及。

3. makefile

CXX = g++
CXXFLAGS = -Wall
LIBES = -lgtest -lgtest_main -lpthread
LPATH = -L/tools/googletest/1.11.0/build/lib  # 替换成自己lib路径
HPATH = -I/tools/googletest/1.11.0/googletest/include/ # 替换成自己的include路径
HPATH += -I/xxx/cpp_freemock/ #替换成自己的include路径UTEST_OBJD = hello_unit_testhello_unit_test:hello_unit_test.cpp${CXX} -o $@ $+ -I ../ ${HPATH} ${CXXFLAGS} ${LIBES} ${LPATH}clean:rm -rf *_unit_test

总结

• CPPMockFree能够支持几乎所有场景下的接口mock
• EXPECT_CALL的使用和gmock基本一致，更多的接口如：SaveArg、SetArgReferee等请参考gmock文档