golden example tests

The tests in this package are used to:

1. that gazelle runs properly (generates correct output from BUILD.in to BUILD.out)
2. that the build artifacts can actually be built (bazel build //...).
3. Generate documentation.

//example/golden:golden_test runs the gazelle tests. Each subdirectory of testdata/* represents a separate test. The BUILD.in file is used as the base, and BUILD.out is expected to be generated. If there is a diff against the actual BUILD.out, the test fails.

The individual gazelle_testdata_example tests package up specific examples and generate a go_bazel_test for the example. So for //example/golden:java, a //example/golden:java_test will run a test that actually tries to build everything within the workspace based on the contents of BUILD.out.

debugging golden example tests

Have any BUILD.bazel files crept into the vendor/ tree? These are globbed in //:all_files and the presence of one will elide files in that package from the glob. You might not see them because they are .gitignored.

bazel query //:all_files --output build > all_files.BUILD

Try and build from the main test workspace. To do that, open up rules_go in the external tree and disable the cleanup function. For example:

$ bazel info output_base
/private/var/tmp/_bazel_pcj/092d6dadaf86f07590903c45033f576e
$ (cd /private/var/tmp/_bazel_pcj/092d6dadaf86f07590903c45033f576e/external/io_bazel_rules_go && code .)
$ code go/tools/bazel_testing/bazel_testing.go

    workspaceDir, cleanup, err := setupWorkspace(args, files)
    defer func() {
+       if err == nil {
+           log.Println("NOTE: skipping cleanup")
+           return
+       }
        if err := cleanup(); err != nil {
            fmt.Fprintf(os.Stderr, "cleanup error: %v\n", err)
            // Don't fail the test on a cleanup error.
            // Some operating systems (windows, maybe also darwin) can't reliably
            // delete executable files after they're run.
        }
    }()

Then, go into the directory that the go_bazel_test creates and run bazel there directly:

$ pushd /private/var/tmp/_bazel_pcj/092d6dadaf86f07590903c45033f576e/bazel_testing/bazel_go_test/main
$ bazel build ...