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bazel-contrib / rules_bazel_integration_test

Rules and macros for executing integration tests that use Bazel. Supports running integration tests with multiple versions of Bazel.
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Bazel Integration Rules

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This repository contains Bazel macros that execute integration tests that use Bazel (e.g. execute tests in a child workspace). The macros support running integration tests with multiple versions of Bazel.

Table of Contents

Quickstart

The following provides a quick introduction on how to use the rules in this repository. Also, check out the documentation, the integration test defined in this repo, and the custom test runner example for more information.

1. Configure your workspace to use rules_bazel_integration_test

Recommended: Add dependency to MODULE.bazel

If you are using Bazel with bzlmod enabled, add the following snippet to your MODULE.bazel file.

bazel_dep(
    name = "rules_bazel_integration_test",
    version = "0.26.1",
    dev_dependency = True,
)

Legacy: Update WORKSPACE

If you are using Bazel with bzlmod disabled, add the following to your WORKSPACE file to add this repository and its dependencies.

http_archive(
    name = "rules_bazel_integration_test",
    sha256 = "65284bfa374ac4f0a66341ed362a79381ce5a2041789129baea5dd6983d3bbad",
    urls = [
        "https://github.com/bazel-contrib/rules_bazel_integration_test/releases/download/v0.26.1/rules_bazel_integration_test.v0.26.1.tar.gz",
    ],
)

load("@rules_bazel_integration_test//bazel_integration_test:deps.bzl", "bazel_integration_test_rules_dependencies")

bazel_integration_test_rules_dependencies()

load("@cgrindel_bazel_starlib//:deps.bzl", "bazel_starlib_dependencies")

bazel_starlib_dependencies()

load("@bazel_skylib//:workspace.bzl", "bazel_skylib_workspace")

bazel_skylib_workspace()

2. List the Bazel versions for testing

Recommended: Add Bazel versions to MODULE.bazel

Load the bazel_binaries extension and specify the Bazel versions to download. All version specifiers supported by Bazelisk are supported.

bazel_binaries = use_extension(
    "@rules_bazel_integration_test//:extensions.bzl",
    "bazel_binaries",
    dev_dependency = True,
)
bazel_binaries.download(version_file = "//:.bazelversion")
bazel_binaries.download(version = "6.0.0")
bazel_binaries.download(version = "last_green")
use_repo(bazel_binaries, "bazel_binaries")

Legacy: Declare the Bazel binaries in the WORKSPACE file

In the WORKSPACE file, add the following to download and prepare the Bazel binaries for testing.

load("@rules_bazel_integration_test//bazel_integration_test:defs.bzl", "bazel_binaries")

bazel_binaries(versions = [
    "//:.bazelversion",
    "6.0.0",
    "last_green",
])

3. Configure the deleted packages for the parent workspace

If you have child workspaces under your parent workspace, you need to tell Bazel to ignore the child workspaces. This can be done in one of two ways:

  1. Add entries to the .bazelignore file in the parent workspace.
  2. Specify a list of deleted packages using the --deleted_packages flag.

For glob() in the parent workspace to find files in the child workspaces, we need to use the deleted packages mechanism.

Add the following to the .bazelrc in the parent workspace. Leave the values blank for now.

# To update these lines, execute 
# `bazel run @rules_bazel_integration_test//tools:update_deleted_packages`
build --deleted_packages=
query --deleted_packages=

To populate the values, we will run a utility that looks for child workspaces (i.e., WORKSPACE files) and find all of the directories that have Bazel build files (i.e., BUILD, BUILD.bazel). Execute the following in a parent workspace directory.

# Populate the --deleted_packages flags in the .bazelrc
$ bazel run @rules_bazel_integration_test//tools:update_deleted_packages

After running the utility, the --deleted_packages entries in the .bazelrc should have a comma-separated list of packages under the child workspaces.

4. Define integration test targets

For the purposes of this example, lets assume that we have an examples directory which contains a subdirectory called simple. The simple directory contains another Bazel workspace (i.e. has its own WORKSPACE file) that does not have a dependency on the parent workspace. We want to execute tests in the simple workspace using different versions of Bazel.

Add the following to the BUILD.bazel file in the examples directory.

load("@bazel_binaries//:defs.bzl", "bazel_binaries")
load(
    "@rules_bazel_integration_test//bazel_integration_test:defs.bzl",
    "bazel_integration_test",
    "bazel_integration_tests",
    "default_test_runner",
    "integration_test_utils",
)

# Declare a test runner to drive the integration tests.
default_test_runner(
    name = "simple_test_runner",
)

# If you only want to execute against a single version of Bazel, use
# bazel_integration_test.
bazel_integration_test(
    name = "simple_test",
    bazel_version = bazel_binaries.versions.current,
    test_runner = ":simple_test_runner",
    workspace_path = "simple",
)

# If you want to execute an integration test using multiple versions of Bazel,
# use bazel_integration_tests. It will generate multiple integration test
# targets with names derived from the base name and the bazel version.
bazel_integration_tests(
    name = "simple_test",
    bazel_versions = bazel_binaries.versions.other,
    test_runner = ":simple_test_runner",
    workspace_path = "simple",
)

# By default, the integration test targets are tagged as `manual`. This
# prevents the targets from being found from most target expansion (e.g.
# `//...`, `:all`). To easily execute a group of integration tests, you may
# want to define a test suite which includes the desired test targets.
test_suite(
    name = "all_integration_tests",
    # If you don't apply the test tags to the test suite, the test suite will
    # be found when `bazel test //...` is executed.
    tags = integration_test_utils.DEFAULT_INTEGRATION_TEST_TAGS,
    tests = [":simple_test"] +
            integration_test_utils.bazel_integration_test_names(
                "simple_test",
                bazel_binaries.versions.other,
            ),
    visibility = ["//:__subpackages__"],
)

The above code defines three test targets: //examples:simple_test, //examples:simple_test_bazel_6_0_0, and //examples:simple_test_bazel_7_0_0-pre_20230215_2. The all_integration_tests target is a test suite that executes all of the integration tests with a single command:

# Execute all of the integration tests
$ bazel test //examples:all_integration_tests

Integration Tests That Depend Upon The Parent Workspace

In the quickstart example, the child workspace does not reference the parent workspace. In many cases, a child workspace will reference the parent workspace using a local_path_override declaration in their MODULE.bazel file to demonstrate functionality from the parent workspace. 

# Child MODULE.bazel at examples/simple/MODULE.bazel

# Reference the parent workspace
local_path_override(
    module_name = "my_parent_workspace",
    path = "../..",
)

This section explains how to use rules_bazel_integration_test in this situation. To review working examples, check out bazel-starlib and swift_bazel.

1. Declare a filegroup to represent the parent workspace files

The child workspace needs to access parent workspace files. To easily reference the files, declare a filegroup at the root of the parent workspace to collect all of the files that the child workspace needs. The values listed in the srcs should include every file and/or package that the child workspaces require.

# This target collects all of the parent workspace files needed by the child workspaces.
filegroup(
    name = "local_repository_files",
    # Include every package that is required by the child workspaces.
    srcs = [
        "BUILD.bazel",
        "WORKSPACE",
        "//foo:all_files",
        "//foo/internal:all_files",
        "//foo/internal/modulemap_parser:all_files",
    ],
    visibility = ["//:__subpackages__"],
)

In every parent workspace package that is listed in the srcs above, create a filegroup globbing all of the files in the package.

# Add to every package that is required by a child workspace.
filegroup(
    name = "all_files",
    srcs = glob(["*"]),
    visibility = ["//:__subpackages__"],
)

2. Update the integration test targets to include the parent workspace files

The bazel_integration_test and bazel_integration_tests declarations include a workspace_files attribute. If not specified, it defaults to a custom glob expression selecting files under the child workspace directory. To include the parent workspace files, add the attribute with an expression that globs the workspace files and the //:local_repository_files target.

bazel_integration_test(
    name = "simple_test",
    bazel_version = CURRENT_BAZEL_VERSION,
    test_runner = ":simple_test_runner",
    workspace_files = integration_test_utils.glob_workspace_files("simple") + [
        "//:local_repository_files",
    ],
    workspace_path = "simple",
)

3. Execute the integration tests

Execute the integration test.

# Execute the integration test called simple_test
$ bazel test //examples:simple_test

Custom Test Runner

For information on implementing a custom test runner, please see the documentation.

Bazelisk Bazel Version Formats

Bazel integration tests require a Bazel version or a Bazel binary to use for the execution of an integration test. Bazel version values can be a Bazel semantic version or a reference to a file that contains a Bazel semantic version (e.g., //:.bazelversion). If you are using Bazelisk to specify the version of Bazel for use in development and CI, then specifying //:.bazelversion as one of the integration test versions may make sense.

Currently, rules_bazel_integration_test only supports Bazel semantic versions in the .bazelversion file. If you are interested in being able to use Bazelisk's <FORK>/<VERSION>, please upvote this issue. If you would like support for another format, please file an issue.