GoogleTest（三）简单类函数测试

### 文件结构

![](/media/202408/2024-08-07_112050_7470410.33625206777428807.png)

***

### test2.h
```cpp
#pragma once
#include <string>
#include <cstring>
class MyString{
private:
    const char * c_string_;
    const MyString& operator=(const MyString& rhs);
public:
    static const char * CloneCString(const char* a_c_string);
    MyString():c_string_(nullptr){}
    explicit MyString(const char * a_c_string):c_string_(nullptr){
        Set(a_c_string);
    }

MyString(const MyString& string) : c_string_(nullptr) {
        Set(string.c_string_);
    }

~MyString(){delete[] c_string_;}

const char * c_string() const {return c_string_;}
    size_t Length() const {return c_string_ == nullptr ? 0 : strlen(c_string_);}
    void Set(const char * c_string);
};
```

### test2.cpp
```cpp
#include "test2.h"

const char* MyString::CloneCString(const char* a_c_sring){
    if (a_c_sring == nullptr){
        return nullptr;
    }

const size_t len = strlen(a_c_sring);
    char * const clone = new char[len+1];
    memcpy(clone, a_c_sring, len+1);
    return clone;
}

void MyString::Set(const char* a_c_string){
    const char * const temp = MyString::CloneCString(a_c_string);
    delete[] c_string_;
    c_string_ = temp;
}
```

### test2Test.cpp
```cpp
#include "gtest/gtest.h"
#include "test2.h"
namespace {

TEST(MyStringTest, DefaultConstractor){
    const MyString s;
    EXPECT_STREQ(nullptr, s.c_string());
    EXPECT_EQ(0u, s.Length());
}

const char kHelloString[] = "Hello world";
TEST(MyStringTest, ConstractorFromCString){
    const MyString s(kHelloString);
    EXPECT_EQ(0, strcmp(s.c_string(), kHelloString));
    EXPECT_EQ(sizeof(kHelloString)/sizeof(kHelloString[0])-1, s.Length());
}

TEST(MyStringTest, CopyConstractor){
    const MyString s1(kHelloString);
    const MyString s2 = s1;
    EXPECT_EQ(0, strcmp(s2.c_string(),kHelloString));
}

TEST(MyStringTest, SetFunction){
    MyString s;
    s.Set(kHelloString);

EXPECT_EQ(0, strcmp(s.c_string(), kHelloString));

s.Set(s.c_string());
    EXPECT_EQ(0, strcmp(s.c_string(), kHelloString));

s.Set(nullptr);
    EXPECT_STREQ(nullptr, s.c_string());
}
}
```
### Makefile
```
CXX = g++
CXXFLAGS = -std=c++14 -Wall -Wextra 
LDFLAGS = -pthread  # GoogleTest需要链接pthread库

# 路径和文件名
SRC_DIR = .
BUILD_DIR = build
TARGET = test2
TEST_TARGET = $(BUILD_DIR)/$(TARGET)_test

# GoogleTest库的路径和名称
GTEST_DIR = $(shell pwd)/../../fake-root
GTEST_LIB = -L$(GTEST_DIR)/lib/ \
			-lgtest -lgtest_main 
			
GTEST_INCLUDE = $(GTEST_DIR)/include

# 源文件和测试文件
SRCS = $(wildcard $(SRC_DIR)/*.cpp)
OBJS = $(SRCS:$(SRC_DIR)/%.cpp=$(BUILD_DIR)/%.o)

# 默认目标：构建测试
all: $(TEST_TARGET)
	@echo "Running tests..."
	./$(TEST_TARGET)

# 生成依赖关系
$(BUILD_DIR)/%.o: $(SRC_DIR)/%.cpp | $(BUILD_DIR)
	$(CXX) $(CXXFLAGS) -I$(GTEST_INCLUDE) -c $< -o $@

# 构建测试目标
$(TEST_TARGET): $(OBJS)
	$(CXX) $(CXXFLAGS) $^ $(GTEST_LIB) $(LDFLAGS) -o $@

# 创建构建目录
$(BUILD_DIR):
	mkdir -p $(BUILD_DIR)

# 清理生成的文件
clean:
	rm -rf $(BUILD_DIR)

.PHONY: all clean
```

### 输出

![](/media/202408/2024-08-07_112604_6221580.7757274754271506.png)