toolchains_llvm VS Google Test

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive") BAZEL_TOOLCHAIN_TAG = "0.7.2" BAZEL_TOOLCHAIN_SHA = "f7aa8e59c9d3cafde6edb372d9bd25fb4ee7293ab20b916d867cd0baaa642529" http_archive( name = "com_grail_bazel_toolchain", sha256 = BAZEL_TOOLCHAIN_SHA, strip_prefix = "bazel-toolchain-{tag}".format(tag = BAZEL_TOOLCHAIN_TAG), canonical_id = BAZEL_TOOLCHAIN_TAG, url = "https://github.com/grailbio/bazel-toolchain/archive/{tag}.tar.gz".format(tag = BAZEL_TOOLCHAIN_TAG), ) load("@com_grail_bazel_toolchain//toolchain:deps.bzl", "bazel_toolchain_dependencies") bazel_toolchain_dependencies() load("@com_grail_bazel_toolchain//toolchain:rules.bzl", "llvm_toolchain") llvm_toolchain( name = "llvm_toolchain", llvm_version = "15.0.5", ) load("@llvm_toolchain//:toolchains.bzl", "llvm_register_toolchains") llvm_register_toolchains() http_archive( name = "com_google_googletest", urls = ["https://github.com/google/googletest/archive/609281088cfefc76f9d0ce82e1ff6c30cc3591e5.zip"], strip_prefix = "googletest-609281088cfefc76f9d0ce82e1ff6c30cc3591e5", )

Yeah the cross-compilation thing is definitely a rough spot. I have one project that's able to work around it via extensive hacks with macros, but at some point I'll need to do it "the right way."

Honestly if the docs had a canonical example of e.g. using unix_cc_toolchain_config (example: [0]) + Bootlin to compile for aarch64, it'd probably go a long way to making things understandable. Because say what you will about the old CROSSTOOL approach, at least there was a nice tutorial for it.

[0] https://github.com/grailbio/bazel-toolchain/blob/f14a8a5de8f...

I'm really not familiar with this issue or Go nor C++ overall, but if all you need is to set up a C++ toolchain, this should be quite simple and solve your issue.

The trick is that to provide Bazel with a custom toolchain involves way more than just setting an environment variable, because Bazel wants to control installing and making available the compiler reliably (e.g., what if `emcc` is not present on the system where Bazel was invoked? Bazel solves that problem by fetching it and building it for that system)

There are projects that provide drop-in support for custom toolchains (e.g., we use this project[0] in Sorbet to fetch and build a custom LLVM/Clang toolchain for every host we build on (rather than relying on the system toolchain). But I'm not aware of a project that has done that for Emscripten. Maybe it would be as easy as plucking out what we've done in our project into a project that others could depend on, but to quote a colleague:

> Setting up a cc toolchain in Bazel is a unique sort of pain.

[0] https://github.com/grailbio/bazel-toolchain/

cmake_minimum_required(VERSION 3.5) project(knn_cpp CXX) include(FetchContent) FetchContent_Declare( googletest GIT_REPOSITORY https://github.com/google/googletest.git GIT_TAG release-1.11.0 ) FetchContent_MakeAvailable(googletest) FetchContent_Declare(matplotplusplus GIT_REPOSITORY https://github.com/alandefreitas/matplotplusplus GIT_TAG origin/master) FetchContent_GetProperties(matplotplusplus) if(NOT matplotplusplus_POPULATED) FetchContent_Populate(matplotplusplus) add_subdirectory(${matplotplusplus_SOURCE_DIR} ${matplotplusplus_BINARY_DIR} EXCLUDE_FROM_ALL) endif() function(knn_cpp_test TEST_NAME TEST_SOURCE) add_executable(${TEST_NAME} ${TEST_SOURCE}) target_link_libraries(${TEST_NAME} PUBLIC matplot) aux_source_directory(${CMAKE_CURRENT_SOURCE_DIR}/../lib LIB_SOURCES) target_link_libraries(${TEST_NAME} PRIVATE gtest gtest_main gmock gmock_main) target_include_directories(${TEST_NAME} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/../) target_sources(${TEST_NAME} PRIVATE ${LIB_SOURCES} ) include(GoogleTest) gtest_discover_tests(${TEST_NAME}) endfunction() knn_cpp_test(LinearAlgebraTest la_test.cc) knn_cpp_test(KnnTest knn_test.cc) knn_cpp_test(UtilsTest utils_test.cc)

Okay, time to start unit tests!!! We will use Unity Test Framework to do unit testing. It is one of widely used testing frameworks alongside with Check, Google Test etc. Just downloading source code, and putting it to the project folder is enough to make it work (that is also why it is portable).

Updating GCC (it happened to GoogleTest).

Roy's project uses Google Test, a C++ testing framework. His testing setup is similar to mine as we both keep source files in one directory and tests in another. The key difference is that I can run the tests using the Visual Studios run button. It was fairly easy to write the new tests as there were existing ones that I could reference to check the syntax!

The Google Test Documentation provides a primer for first-time users. The primer introduces some basic concepts and terminology, some of which I've been able to learn for this lab exercise.

> git submodule add https://github.com/google/googletest.git > git submodule update --init --recursive

cmake_minimum_required(VERSION 3.14) project(my_project) # GoogleTest requires at least C++14 set(CMAKE_CXX_STANDARD 14) set(CMAKE_CXX_STANDARD_REQUIRED ON) include(FetchContent) FetchContent_Declare( googletest URL https://github.com/google/googletest/archive/03597a01ee50ed33e9dfd640b249b4be3799d395.zip ) # For Windows: Prevent overriding the parent project's compiler/linker settings set(gtest_force_shared_crt ON CACHE BOOL "" FORCE) FetchContent_MakeAvailable(googletest) enable_testing() add_executable( hello_test hello_test.cpp ) target_link_libraries( hello_test GTest::gtest_main ) include(GoogleTest) gtest_discover_tests(hello_test)

FetchContent\_Declare(googletestGIT\_REPOSITORY [[email protected]](mailto:[email protected]):googletest.git [https://github.com/google/googletest.git](https://github.com/google/googletest.git)GIT\_TAG release-1.12.1)FetchContent\_MakeAvailable(googletest)

Not sure about CppUnit but I can speak to my previous experience using the googletest framework which compiles your tests to an executable, and since it's a very simple framework we were able to cross-compile and run directly on our device. We just had to hook up a device to the server that was running the CI so it could flash it when needed. That basically meant that our process was: