山寨一个Catch2的SECTION

Catch2 是一个 C++ 单元测试库，吹嘘自己比 NUnit 和 xUnit 还要高明， 支持在 TEST_CASE() 中的多个 SECTION， 意思是说 SECTION 外头的代码相当于setup 和 teardown，section 内部则被认为是实际的 test case， 这种写法可以省很多代码，云云：

https://github.com/catchorg/Catch2/blob/v2.x/docs/tutorial.md#test-cases-and-sections

然而 Catch2 文档里卖关子，不说原理。 我们来山寨一个：

test2.cpp

#include <stdio.h>
#include <vector>static int section_idx = 0;void test()
{printf("comman setup\n");std::vector<int> v(5);if (section_idx == 0){printf("--- check 1\n");v.resize(10);printf("v.size() = %d\n", v.size());}if (section_idx == 1){printf("--- check 2\n");printf("v.size() = %d\n", v.size());}if (section_idx == 2){printf("--- check 3\n");v.resize(20);printf("v.size() = %d\n", v.size());}if (section_idx == 3){printf("--- check 4\n");printf("v.size() = %d\n", v.size());}printf("\n");section_idx++;
}int main()
{for (int i = 0; i < 4 ; i++){test();}return 0;
}

改进一下：
test3.cpp:

#include <stdio.h>
#include <vector>static int section_idx = 0;void test()
{printf("comman setup\n");std::vector<int> v(5);auto f0 = [&]() -> void{printf("--- check 1\n");v.resize(10);printf("v.size() = %d\n", v.size());};if (section_idx == 0)f0();auto f1 = [&]() -> void{printf("--- check 2\n");printf("v.size() = %d\n", v.size());};if (section_idx == 1)f1();auto f2 = [&]() -> void{printf("--- check 3\n");v.resize(20);printf("v.size() = %d\n", v.size());};if (section_idx == 2)f2();auto f3 = [&]() -> void{printf("--- check 4\n");printf("v.size() = %d\n", v.size());};if (section_idx == 3)f3();printf("\n");section_idx++;
}int main()
{for (int i = 0; i < 4 ; i++){test();}return 0;
}

再改进一下:

#include <stdio.h>
#include <vector>static int section_idx = 0;
int section_num = 0;void test()
{static bool inited = false;printf("comman setup\n");std::vector<int> v(5);auto f0 = [&]() -> void{printf("--- check 1\n");v.resize(10);printf("v.size() = %d\n", v.size());};if (!inited)section_num++;else{if (section_idx == 0)f0();}auto f1 = [&]() -> void{printf("--- check 2\n");printf("v.size() = %d\n", v.size());};if (!inited)section_num++;else{if (section_idx == 1)f1();}auto f2 = [&]() -> void{printf("--- check 3\n");v.resize(20);printf("v.size() = %d\n", v.size());};if (!inited)section_num++;else{if (section_idx == 2)f2();}auto f3 = [&]() -> void{printf("--- check 4\n");printf("v.size() = %d\n", v.size());};if (!inited)section_num++;else{if (section_idx == 3)f3();}printf("\n");section_idx++;inited = true;
}int main()
{test();for (int i = 0; i < section_num ; i++){test();}return 0;
}

结果:

➜  shanzhai_catch2 ./a.out
comman setupcomman setup
--- check 2
v.size() = 5comman setup
--- check 3
v.size() = 20comman setup
--- check 4
v.size() = 5comman setup

成功!