有没有办法改进 starlark 的 unittest 错误报告？

Question

我正在按照 https://docs.bazel.build/versions/master/skylark/testing.html 为我的项目编写分析时间测试，我想知道报告失败的最有用的方法是什么。

使用unittest.bzl模块，我使用asserts.equals、asserts.true等，发现日志中的错误报告有些欠缺。例如，如果asserts.true 失败，则错误消息是Expected condition to be true, but was false，没有提及哪一行，或者它预期为真的条件是什么。在一个包含大量测试的文件中，这不是很有用！我知道可以将消息作为参数添加到这些断言中，但是为每个断言定制消息也感觉不理想。有没有办法获得由断言失败引起的回溯？或任何其他访问断言失败的行号/详细信息的方式？

Answer 1

我从您的链接中获取了minimal example，并将latest Skylib 版本添加到新的工作空间。然后我更改了_provider_contents_test_impl 中的预期值以使测试失败。

下面是完整的输出，注意DEBUG，其中包含很多有用的信息（文件、行、期望值、实际值）。

$ bazel test //mypkg:myrules_test                                             
DEBUG: /home/user/.cache/bazel/_bazel_user/863abec759a50d843603ddf033727331/external/bazel_skylib/lib/unittest.bzl:351:10: In test _provider_contents_test_impl from //mypkg:myrules_test.bzl: Expected "some valuexxxxx", but got "some value"
INFO: Analyzed target //mypkg:provider_contents_test (0 packages loaded, 0 targets configured).
INFO: Found 1 test target...
FAIL: //mypkg:provider_contents_test (see /home/user/.cache/bazel/_bazel_user/863abec759a50d843603ddf033727331/execroot/__main__/bazel-out/k8-fastbuild/testlogs/mypkg/provider_contents_test/test.log)
Target //mypkg:provider_contents_test up-to-date:
  bazel-bin/mypkg/provider_contents_test.sh
INFO: Elapsed time: 0.108s, Critical Path: 0.04s
INFO: 2 processes: 2 linux-sandbox.
INFO: Build completed, 1 test FAILED, 2 total actions
//mypkg:provider_contents_test                                           FAILED in 0.0s
  /home/user/.cache/bazel/_bazel_user/863abec759a50d843603ddf033727331/execroot/__main__/bazel-out/k8-fastbuild/testlogs/mypkg/provider_contents_test/test.log

INFO: Build completed, 1 test FAILED, 2 total actions

还支持回溯，例如，请参阅 this bug report。

tion，实际值）。

$ bazel test //mypkg:myrules_test                                             
DEBUG: /home/user/.cache/bazel/_bazel_user/863abec759a50d843603ddf033727331/external/bazel_skylib/lib/unittest.bzl:351:10: In test _provider_contents_test_impl from //mypkg:myrules_test.bzl: Expected "some valuexxxxx", but got "some value"
INFO: Analyzed target //mypkg:provider_contents_test (0 packages loaded, 0 targets configured).
INFO: Found 1 test target...
FAIL: //mypkg:provider_contents_test (see /home/user/.cache/bazel/_bazel_user/863abec759a50d843603ddf033727331/execroot/__main__/bazel-out/k8-fastbuild/testlogs/mypkg/provider_contents_test/test.log)
Target //mypkg:provider_contents_test up-to-date:
  bazel-bin/mypkg/provider_contents_test.sh
INFO: Elapsed time: 0.108s, Critical Path: 0.04s
INFO: 2 processes: 2 linux-sandbox.
INFO: Build completed, 1 test FAILED, 2 total actions
//mypkg:provider_contents_test                                           FAILED in 0.0s
  /home/user/.cache/bazel/_bazel_user/863abec759a50d843603ddf033727331/execroot/__main__/bazel-out/k8-fastbuild/testlogs/mypkg/provider_contents_test/test.log

INFO: Build completed, 1 test FAILED, 2 total actions

还支持回溯，例如，请参阅 this bug report。

请注意，asserts.equals 将在失败时打印实际值，但 asserts.true 不会 - 但您可以使用 asserts.equals(env, True, test_val, msg) 轻松解决此问题。