From fe775191c7f0466225dc7aefc405d07b0f3883dd Mon Sep 17 00:00:00 2001 From: DarkSun Date: Wed, 19 Jan 2022 05:02:38 +0800 Subject: [PATCH] =?UTF-8?q?=E9=80=89=E9=A2=98[tech]:=2020220118=20Perform?= =?UTF-8?q?=20unit=20tests=20using=20GoogleTest=20and=20CTest?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit sources/tech/20220118 Perform unit tests using GoogleTest and CTest.md --- ...m unit tests using GoogleTest and CTest.md | 371 ++++++++++++++++++ 1 file changed, 371 insertions(+) create mode 100644 sources/tech/20220118 Perform unit tests using GoogleTest and CTest.md diff --git a/sources/tech/20220118 Perform unit tests using GoogleTest and CTest.md b/sources/tech/20220118 Perform unit tests using GoogleTest and CTest.md new file mode 100644 index 0000000000..843802d802 --- /dev/null +++ b/sources/tech/20220118 Perform unit tests using GoogleTest and CTest.md @@ -0,0 +1,371 @@ +[#]: subject: "Perform unit tests using GoogleTest and CTest" +[#]: via: "https://opensource.com/article/22/1/unit-testing-googletest-ctest" +[#]: author: "Stephan Avenwedde https://opensource.com/users/hansic99" +[#]: collector: "lujun9972" +[#]: translator: " " +[#]: reviewer: " " +[#]: publisher: " " +[#]: url: " " + +Perform unit tests using GoogleTest and CTest +====== +Using unit tests will likely improve your code's quality and do so +without disturbing your workflow. +![Team checklist and to dos][1] + +This article is a follow-up to my last article [Set up a build system with CMake and VSCodium][2]. + +In the last article, I showed how to configure a build system based on [VSCodium][3] and [CMake][4]. This article refines this setup by integrating meaningful unit tests using [GoogleTest][5] and [CTest][6]. + +If not already done, clone the [repository][7], open it in VSCodium and checkout the tag _devops_2_ by clicking on the _main_-branch symbol (red marker) and choosing the branch (yellow marker): + +![VSCodium tag][8] + +Stephan Avenwedde (CC BY-SA 4.0) + +Alternatively, open the command line and type: + + +``` +`$ git checkout tags/devops_2` +``` + +### GoogleTest + +GoogleTest is a platform-independent, open source C++ testing framework. Even though GoogleTest is not meant to be exclusively for unit tests, I will use it to define unit tests for the _Generator_ library. In general, a unit test should verify the behavior of a single, logical unit. The _Generator_ library is one unit, so I'll write some meaningful tests to ensure proper function. + +Using GoogleTest, the test cases are defined by assertions macros. Processing an assertion generates one of the following results: + + * _Success_: Test passed. + * _Nonfatal failure_: Test failed, but the test function will continue. + * _Fatal failure_: Test failed, and the test function will be aborted. + + + +The assertions macros follow this scheme to distinguish a fatal from a nonfatal failure: + + * `ASSERT_*` fatal failure, function is aborted. + * `EXPECT_*` nonfatal failure, function is not aborted. + + + +Google recommends using `EXPECT_*` macros as they allow the test to continue when the tests define multiple assertions. An assertion macro takes two arguments: The first argument is the name of the test group (a freely selectable string), and the second argument is the name of the test itself. The _Generator_ library just defines the function _generate(...)_, therefore the tests in this article belong to the same group: _GeneratorTest_. + +The following unit tests for the _generate(...)_ function can be found in [GeneratorTest.cpp][9]. + +#### Reference check + +The [generate(...)][10] function takes a reference to a [std::stringstream][11] as an argument and returns the same reference. So the first test is to check if the passed reference is the same reference which the function returns. + + +``` + + +TEST(GeneratorTest, ReferenceCheck){ +    const int NumberOfElements = 10; +    std::stringstream buffer; +    EXPECT_EQ( +        std::addressof(buffer), +        std::addressof(Generator::generate(buffer, NumberOfElements)) +    ); +} + +``` + +Here I use [std::addressof][12] to check if the address of the returned object refers to the same object I provided as input. + +#### Number of elements + +This test checks if the number of elements in the stringstream reference matches the number given as an argument. + + +``` + + +TEST(GeneratorTest, NumberOfElements){ +    const int NumberOfElements = 50; +    int nCalcNoElements = 0; + +    std::stringstream buffer; + +    Generator::generate(buffer, NumberOfElements); +    std::string s_no; + +    while(std::getline(buffer, s_no, ' ')) { +        nCalcNoElements++; +    } + +    EXPECT_EQ(nCalcNoElements, NumberOfElements); +} + +``` + +#### Shuffle + +This test checks the proper working of the random engine. If I invoke the _generate_ function two times in a row, I expect not to get the same result. + + +``` + + +TEST(GeneratorTest, Shuffle){ + +    const int NumberOfElements = 50; + +    std::stringstream buffer_A; +    std::stringstream buffer_B; + +    Generator::generate(buffer_A, NumberOfElements); +    Generator::generate(buffer_B, NumberOfElements); + +    EXPECT_NE(buffer_A.str(), buffer_B.str()); +} + +``` + +#### Checksum + +This is the largest test. It checks whether the sum of the digits of a numerical series from 1 to _n_ is the same as the sum of the shuffled output series. I expect that the sum matches as the _generate(...)_ function should simply create a shuffled variant of such a series. + + +``` + + +TEST(GeneratorTest, CheckSum){ + +    const int NumberOfElements = 50; +    int nChecksum_in = 0; +    int nChecksum_out = 0; + +    std::vector<int> vNumbersRef(NumberOfElements); // Input vector +    std::iota(vNumbersRef.begin(), vNumbersRef.end(), 1); // Populate vector + +    // Calculate reference checksum +    for(const int n : vNumbersRef){ +        nChecksum_in += n; +    } + +    std::stringstream buffer; +    Generator::generate(buffer, NumberOfElements); + +    std::vector<int> vNumbersGen; // Output vector +    std::string s_no; + +    // Read the buffer back back to the output vector +    while(std::getline(buffer, s_no, ' ')) { +        vNumbersGen.push_back(std::stoi(s_no)); +    } + +    // Calculate output checksum +    for(const int n : vNumbersGen){ +        nChecksum_out += n; +    } + +    EXPECT_EQ(nChecksum_in, nChecksum_out); +} + +``` + +The above tests can also be debugged like an ordinary C++ application. + +### CTest + +In addition to the in-code unit test, the [CTest][6] utility lets me define tests that can be performed on executables. In a nutshell, I call the executable with certain arguments and match the output with [regular expressions][13]. This lets me simply check how the executable behaves with incorrect command-line arguments. The tests are defined in the top level [CMakeLists.txt][14]. Here is a closer look at three test cases: + +#### Regular usage + +If a positive integer is provided as a command-line argument, I expect the executable to produce a series of numbers separated by whitespace: + + +``` + + +add_test(NAME RegularUsage COMMAND Producer 10) +set_tests_properties(RegularUsage +    PROPERTIES PASS_REGULAR_EXPRESSION "^[0-9 ]+" +) + +``` + +#### No argument + +If no argument is provided, the program should exit immediately and display the reason why: + + +``` + + +add_test(NAME NoArg COMMAND Producer) +set_tests_properties(NoArg +    PROPERTIES PASS_REGULAR_EXPRESSION "^Enter the number of elements as argument" +) + +``` + +#### Wrong argument + +Providing an argument that cannot be converted into an integer should also cause an immediate exit with an error message. This test invokes the _Producer_ executable with the command line parameter*"ABC"*: + + +``` + + +add_test(NAME WrongArg COMMAND Producer ABC) +set_tests_properties(WrongArg +    PROPERTIES PASS_REGULAR_EXPRESSION "^Error: Cannot parse" +) + +``` + +#### Testing the tests + +To run a single test and see how it is processed, invoke `ctest` from the command line providing the following arguments: + + * Run single tst: `-R ` + * Enable verbose output: `-VV` + + + +Here is the command `ctest -R Usage -VV:` + + +``` + + +$ ctest -R Usage -VV +UpdatecTest Configuration from :/home/stephan/Documents/cpp_testing sample/build/DartConfiguration.tcl +UpdateCTestConfiguration from :/home/stephan/Documents/cpp_testing sample/build/DartConfiguration.tcl +Test project /home/stephan/Documents/cpp_testing sample/build +Constructing a list of tests +Done constructing a list of tests +Updating test list for fixtures +Added 0 tests to meet fixture requirements +Checking test dependency graph... +Checking test dependency graph end + +``` + +In this code block, I invoked a test named _Usage_. + +This ran the executable with no command-line arguments: + + +``` + + +test 3 +    Start 3: Usage +3: Test command: /home/stephan/Documents/cpp testing sample/build/Producer + +``` + +The test failed because the output didn't match the regular expression `[^[0-9]+]`. + + +``` + + +3: Enter the number of elements as argument +1/1 test #3. Usage ................ + +Failed Required regular expression not found. +Regex=[^[0-9]+] + +0.00 sec round. + +0% tests passed, 1 tests failed out of 1 +Total Test time (real) = +0.00 sec +The following tests FAILED: +3 - Usage (Failed) +Errors while running CTest +$ + +``` + +To run all tests (including the one defined with GoogleTest), navigate to the _build_ directory and run `ctest`: + +![CTest run][15] + +Stephan Avenwedde (CC BY-SA 4.0) + +Inside VSCodium, click on the area marked yellow in the info bar to invoke CTest. If all tests pass, the following output is displayed: + +![VSCodium][16] + +Stephan Avenwedde (CC BY-SA 4.0) + +### Automate testing with Git Hooks + +By now, running the tests is an additional step for the developer. The developer could also commit and push code that doesn't pass the tests. Thanks to [Git Hooks][17], I can implement a mechanism that automatically runs the tests and prevents the developer from accidentally committing faulty code. + +Navigate to `.git/hooks`, create an empty file named _pre-commit_, and copy and paste the following code: + + +``` + + +#!/usr/bin/sh + +(cd build; ctest --output-on-failure -j6) + +``` + +After it, make this file executable: + + +``` +`$ chmod +x pre-commit` +``` + +This script invokes CTest when trying to perform a commit. If a test fails, like in the screenshot below, the commit is aborted: + +![Commit failed][18] + +Stephan Avenwedde (CC BY-SA 4.0) + +If the tests succeed, the commit is processed, and the output looks like this: + +![Commit succeeded][19] + +Stephan Avenwedde (CC BY-SA 4.0) + +The described mechanism is only a soft barrier: A developer could still commit faulty code using `git commit --no-verify`. I can ensure that only working code is pushed by configuring a build server. This topic will be part of a separate article. + +### Summary + +The techniques mentioned in this article are easy to implement and help you quickly find bugs in your code. Using unit tests will likely improve your code's quality and, as I have shown, do so without disturbing your workflow. The GoogleTest framework provides features for every conceivable scenario; I only used a subset of its functionality. At this point, I also want to mention the [GoogleTest Primer][20], which gives you an overview of the ideas, opportunities, and features of the framework. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/22/1/unit-testing-googletest-ctest + +作者：[Stephan Avenwedde][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/hansic99 +[b]: https://github.com/lujun9972 +[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/todo_checklist_team_metrics_report.png?itok=oB5uQbzf (Team checklist and to dos) +[2]: https://opensource.com/article/22/1/devops-cmake +[3]: https://vscodium.com/ +[4]: https://cmake.org/ +[5]: https://github.com/google/googletest +[6]: https://cmake.org/cmake/help/latest/manual/ctest.1.html +[7]: https://github.com/hANSIc99/cpp_testing_sample +[8]: https://opensource.com/sites/default/files/cpp_unit_test_vscodium_tag.png (VSCodium tag) +[9]: https://github.com/hANSIc99/cpp_testing_sample/blob/main/Generator/GeneratorTest.cpp +[10]: https://github.com/hANSIc99/cpp_testing_sample/blob/main/Generator/Generator.cpp +[11]: https://en.cppreference.com/w/cpp/io/basic_stringstream +[12]: https://en.cppreference.com/w/cpp/memory/addressof +[13]: https://en.wikipedia.org/wiki/Regular_expression +[14]: https://github.com/hANSIc99/cpp_testing_sample/blob/main/CMakeLists.txt +[15]: https://opensource.com/sites/default/files/cpp_unit_test_ctest_run.png (CTest run) +[16]: https://opensource.com/sites/default/files/cpp_unit_test_ctest_vscodium.png (VSCodium) +[17]: https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks +[18]: https://opensource.com/sites/default/files/cpp_unit_test_git_hook_commit_failed.png (Commit failed) +[19]: https://opensource.com/sites/default/files/cpp_unit_test_git_hook_commit_succeeded.png (Commit succeeded) +[20]: https://google.github.io/googletest/primer.html