如何在Bazel项目中建立Catch2

Question

我已经启动了一个简单的C++项目，该项目使用Bazel作为构建系统，并希望将Catch2作为测试框架添加到其中。

到目前为止，我的项目就是这样的：

WORKSPACE -> empty file
src/
  Money.hpp
  Money.cpp
BUILD

在哪里构建是公正的

cc_library(
  name = "Money",
  srcs = ["Money.cpp"],
  hdrs = ["Money.hpp"]
)

我希望能够为每个cc_library创建测试，在本例中为Money创建测试。我试着设置它，但与Catch2 main混淆了。任何关于如何做到最好的建议都是非常感谢的！

Answer 1

经过反复学习，我成功地完成了Bazel0.16.1和Catch2 2.4.0的工作。

首先，让我们在test/旁边创建目录src/，以便将测试保存在那里。

为了使用Catch2，我们需要下载catch.hpp。Catch2只是标头库，这意味着我们只需要一个文件。我把它放在test/vendor/catch2/里了。

然后，我们需要向bazel定义如何使用它。在test/vendor/catch2中，我们创建以下构建文件：

cc_library(
  name = "catch2",
  hdrs = ["catch.hpp"],
  visibility = ["//test:__pkg__"]
)

现在Bazel将Catch2识别为一个库。我们添加了可见性属性，以便可以从//test包(由/test目录中的构建来定义)使用它。

其次，Catch2要求我们定义一个具有正确定义的主方法的翻译单元。按照他们的指示，我们创建test/main.cpp文件：

#define CATCH_CONFIG_MAIN
#include "catch.hpp"

现在，我们用test/Money.test.cpp编写我们的测试

#include "catch.hpp"
#include "Money.hpp"

TEST_CASE("Money works.") {
  ...
}

最后，我们需要向Bazel解释如何构建这一切。注意，我们在文件中直接包含了Money.hpp和catch.hpp，没有相对路径，所以这也是我们需要记住的问题。我们创建以下test/BUILD文件：

# We describe to Bazel how to build main.cpp.
# It includes "catch.hpp" directly, so we need to add
# "-Itest/vendor/catch2" compiler option.
cc_library(
    name = "catch-main",
    srcs = ["main.cpp"],
    copts = ["-Itest/vendor/catch2"],
    deps = [
        "//test/vendor/catch2"
    ]
)

# Here we define our test. It needs to build together with the catch2
# main that we defined above, so we add it to deps. We directly
# include src/Money.hpp and test/vendor/catch2/catch.hpp in
# Money.test.cpp, so we need to add their parent directories as copts.
# We also add Money and catch2 as dependencies.
cc_test(
    name = "Money",
    srcs = ["Money.test.cpp"],
    copts = ["-Itest/vendor/catch2/", "-Isrc/"],
    deps = [
        # Or "//test/vendor/catch2:catch2", it is the same.
        "//test/vendor/catch2",
        "catch-main",
        "//src:Money"
    ]
)

# Test suite that runs all the tests.
test_suite(
    name = "all-tests",
    tests = [
        "Money"
    ]
)

最后，我们只需要将visibility属性添加到src/BUILD中，这样就可以通过测试访问它。我们修改src/BUILD如下所示：

cc_library(
    name = "Money",
    srcs = ["Money.cpp"],
    hdrs = ["Money.hpp"],
    visibility = ["//test:__pkg__"]
)

最后的文件结构如下所示：

WORKSPACE
src/
  Money.hpp
  Money.cpp
  BUILD
test/
  BUILD
  main.cpp
  Money.test.cpp
  vendor/
    catch2/
      catch.hpp
      BUILD

现在您可以使用bazel test //test:all-tests运行测试了！

我用这个例子创建了Github，您可以查看它的这里。我还把它变成了博客帖子。

Answer 2

Catch2 (v2.13.0)由Bazel提供支持。

示例

WORKSPACE.bazel

workspace(name = "Catch2Demo")

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
    name = "catch2",
    strip_prefix = "Catch2-2.13.0",
    urls = ["https://github.com/catchorg/Catch2/archive/v2.13.0.tar.gz"],
)

BUILD.bazel

cc_test(
    name = "my_test",
    srcs = ["my_test.cpp"],
    defines = ["CATCH_CONFIG_MAIN"],
    deps = [
        "@catch2",
    ],
)

my_test.cpp

#include <catch2/catch.hpp>

unsigned int Factorial( unsigned int number ) {
    return number <= 1 ? number : Factorial(number-1)*number;
}

TEST_CASE( "Factorials are computed", "[factorial]" ) {
    REQUIRE( Factorial(1) == 1 );
    REQUIRE( Factorial(2) == 2 );
    REQUIRE( Factorial(3) == 6 );
    REQUIRE( Factorial(10) == 3628800 );
}

Answer 3

Catch2 v3 (3.1.1)

Catch2 v3被拆分为多个标头，需要C++14或更高版本，并且不再仅限于标头，这会稍微改变一些事情。

WORKSPACE.bazel：

workspace(name = "Catch2Demo")

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
    name = "catch2",
    strip_prefix = "Catch2-3.1.1",
    urls = ["https://github.com/catchorg/Catch2/archive/v3.1.1.tar.gz"],
)

BUILD.bazel：

cc_test(
    name = "my_test",
    srcs = ["my_test.cpp"],
    copts = ["-std=c++14"],
    deps = [
        "@catch2//:catch2_main",
    ],
)

my_test.cpp：

#include <catch2/catch_test_macros.hpp>

unsigned int Factorial( unsigned int number ) {
    return number <= 1 ? number : Factorial(number-1)*number;
}

TEST_CASE( "Factorials are computed", "[factorial]" ) {
REQUIRE( Factorial(1) == 1 );
REQUIRE( Factorial(2) == 2 );
REQUIRE( Factorial(3) == 6 );
REQUIRE( Factorial(10) == 3628800 );
}

现在，使用

bazelisk test //:my_test --cxxopt='-std=c++14'