为模板类创建gtest值参数化测试

问题描述

我有一个类型的模板类

<size_t N>
class Line {
   ...
};

如何为该类的多个实例创建测试?例如第< 1>，第< 2>，...

How could I could I create a test for several instances of this class? e.g. Line<1>, Line<2>, ...

我已经检查了文档，并且有:

I have checked the documentation and there are:

• 值参数化测试，用于运行时值

• Value-Parametrized tests, for run-time values

类型参数化测试，使您可以在编译时更改类型名称.

Type-Parametrized tests, which allow you to change the typename at compile time.

但是，我在编译时没有发现任何可以更改值的内容.

However, I do not find anything to change values at compile-time.

推荐答案

Googletest没有可用于生成测试结果的现成解决方案所需的一组非类型模板参数的模板.

Googletest has no ready-to-wear solution for generating tests over atemplate for a set of non-type template parameters, as you want.

假设使用C ++ 11或更高版本，则可以利用 std::integral_constant<T,N> 创建一个唯一表示std::size_t范围中每个范围的类您要对其进行测试以覆盖Line<N>的参数N，并使用std::integral_constant<std::size_t,N>作为N的代理以构造TYPED_TEST_CASE和关联的TYPED_TEST.像这样:

Assuming C++11 or later, you can take advantage of std::integral_constant<T,N>to create a class that uniquely represents each of the range of std::size_tparameters N for which you want tests covering Line<N>, and use std::integral_constant<std::size_t,N>as a proxy for N to construct a TYPED_TEST_CASE and associated TYPED_TESTs. Like so:

用于说明的玩具Line类:

Line.h

#ifndef LINE_H
#define LINE_H
#include <cstddef>

template <std::size_t N>
class Line {
public:
    static constexpr std::size_t capacity() {
        return N;
    }
    explicit Line(std::size_t n)
    : _length{n < N ? n : N}{};

    std::size_t length() const {
        return _length;
    }

private:
    std::size_t _length = 0;

};

#endif

Googletest测试运行器:

Googletest test runner:

line_test.cpp

#include <gtest/gtest.h>
#include <type_traits>
#include "line.h"

template <typename T>
class line_tester : public ::testing::Test{};

using test_types = ::testing::Types<
    std::integral_constant<std::size_t,2>,
    std::integral_constant<std::size_t,3>,
    std::integral_constant<std::size_t,5>>;

TYPED_TEST_CASE(line_tester, test_types);

TYPED_TEST(line_tester, get_capacity) {
    static constexpr std::size_t n = TypeParam::value;
    ASSERT_EQ(n,Line<n>::capacity());
}

TYPED_TEST(line_tester, set_length_preserved) {
    Line<TypeParam::value> line{1};
    ASSERT_EQ(line.length(),1);
}

TYPED_TEST(line_tester, set_length_trunctated) {
    static constexpr std::size_t n = TypeParam::value;
    Line<n> line{999};
    ASSERT_EQ(line.length(),Line<n>::capacity());
}

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

运行方式如下:

$ ./line_tester
[==========] Running 9 tests from 3 test cases.
[----------] Global test environment set-up.
[----------] 3 tests from line_tester/0, where TypeParam = std::integral_constant<unsigned long, 2ul>
[ RUN      ] line_tester/0.get_capacity
[       OK ] line_tester/0.get_capacity (0 ms)
[ RUN      ] line_tester/0.set_length_preserved
[       OK ] line_tester/0.set_length_preserved (0 ms)
[ RUN      ] line_tester/0.set_length_trunctated
[       OK ] line_tester/0.set_length_trunctated (0 ms)
[----------] 3 tests from line_tester/0 (1 ms total)

[----------] 3 tests from line_tester/1, where TypeParam = std::integral_constant<unsigned long, 3ul>
[ RUN      ] line_tester/1.get_capacity
[       OK ] line_tester/1.get_capacity (0 ms)
[ RUN      ] line_tester/1.set_length_preserved
[       OK ] line_tester/1.set_length_preserved (0 ms)
[ RUN      ] line_tester/1.set_length_trunctated
[       OK ] line_tester/1.set_length_trunctated (0 ms)
[----------] 3 tests from line_tester/1 (0 ms total)

[----------] 3 tests from line_tester/2, where TypeParam = std::integral_constant<unsigned long, 5ul>
[ RUN      ] line_tester/2.get_capacity
[       OK ] line_tester/2.get_capacity (0 ms)
[ RUN      ] line_tester/2.set_length_preserved
[       OK ] line_tester/2.set_length_preserved (0 ms)
[ RUN      ] line_tester/2.set_length_trunctated
[       OK ] line_tester/2.set_length_trunctated (0 ms)
[----------] 3 tests from line_tester/2 (0 ms total)

[----------] Global test environment tear-down
[==========] 9 tests from 3 test cases ran. (1 ms total)
[  PASSED  ] 9 tests.

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