title: Karma layout: default stylesheet: docs

Karma rules for Bazel

WARNING: this is beta-quality software. Breaking changes are likely. Not recommended for production use without expert support.

The Karma rules run karma tests with Bazel.

Installation

Add the @bazel/karma npm package to your devDependencies in package.json.

Your WORKSPACE should declare a yarn_install or npm_install rule named npm. It should then install the rules found in the npm packages using the `install_bazel_dependencies' function. See https://github.com/bazelbuild/rules_nodejs/#quickstart

This causes the @bazel/karma package to be installed as a Bazel workspace named npm_bazel_karma.

Now add this to your WORKSPACE to install the Karma dependencies:

# Fetch transitive Bazel dependencies of npm_bazel_karma
load("@npm_bazel_karma//:package.bzl", "npm_bazel_karma_dependencies")
npm_bazel_karma_dependencies()

This installs the io_bazel_rules_webtesting repository, if you haven't installed it earlier.

Finally, configure the rules_webtesting:

# Set up web testing, choose browsers we can test on
load("@io_bazel_rules_webtesting//web:repositories.bzl", "browser_repositories", "web_test_repositories")

web_test_repositories()
browser_repositories(
    chromium = True,
)

Installing with self-managed dependencies

If you didn‘t use the yarn_install or npm_install rule to create an npm workspace, you’ll have to declare a rule in your root BUILD.bazel file to execute karma:

# Create a karma rule to use in ts_web_test_suite karma
# attribute when using self-managed dependencies
nodejs_binary(
    name = "karma/karma",
    entry_point = "//:node_modules/karma/bin/karma",
    # Point bazel to your node_modules to find the entry point
    node_modules = ["//:node_modules"],
)

karma_web_test

Runs unit tests in a browser with Karma.

When executed under bazel test, this uses a headless browser for speed. This is also because bazel test allows multiple targets to be tested together, and we don't want to open a Chrome window on your machine for each one. Also, under bazel test the test will execute and immediately terminate.

Running under ibazel test gives you a “watch mode” for your tests. The rule is optimized for this case - the test runner server will stay running and just re-serve the up-to-date JavaScript source bundle.

To debug a single test target, run it with bazel run instead. This will open a browser window on your computer. Also you can use any other browser by opening the URL printed when the test starts up. The test will remain running until you cancel the bazel run command.

This rule will use your system Chrome by default. In the default case, your environment must specify CHROME_BIN so that the rule will know which Chrome binary to run. Other browsers and customLaunchers may be set using the a base Karma configuration specified in the config_file attribute.

Usage

karma_web_test(srcs, deps, data, configuration_env_vars, bootstrap, runtime_deps, static_files, config_file, tags, kwargs)

`srcs`

A list of JavaScript test files

Defaults to []

`deps`

Other targets which produce JavaScript such as ts_library

Defaults to []

`data`

Runtime dependencies

Defaults to []

`configuration_env_vars`

Pass these configuration environment variables to the resulting binary. Chooses a subset of the configuration environment variables (taken from ctx.var), which also includes anything specified via the --define flag. Note, this can lead to different outputs produced by this rule.

Defaults to []

`bootstrap`

JavaScript files to include before the module loader (require.js). For example, you can include Reflect,js for TypeScript decorator metadata reflection, or UMD bundles for third-party libraries.

Defaults to []

`runtime_deps`

Dependencies which should be loaded after the module loader but before the srcs and deps. These should be a list of targets which produce JavaScript such as ts_library. The files will be loaded in the same order they are declared by that rule.

Defaults to []

`static_files`

Arbitrary files which are available to be served on request. Files are served at: /base/<WORKSPACE_NAME>/<path-to-file>, e.g. /base/npm_bazel_typescript/examples/testing/static_script.js

Defaults to []

`config_file`

User supplied Karma configuration file. Bazel will override certain attributes of this configuration file. Attributes that are overridden will be outputted to the test log.

Defaults to None

`tags`

Standard Bazel tags, this macro adds tags for ibazel support

Defaults to []

`kwargs`

Passed through to karma_web_test

karma_web_test_suite

Defines a test_suite of web_test targets that wrap a karma_web_test target.

This macro also accepts all parameters in karma_web_test. See karma_web_test docs for details.

Usage

karma_web_test_suite(name, browsers, args, browser_overrides, config, flaky, local, shard_count, size, tags, test_suite_tags, timeout, visibility, web_test_data, wrapped_test_tags, remaining_keyword_args)

`name`

The base name of the test

`browsers`

A sequence of labels specifying the browsers to use.

Defaults to None

`args`

Args for web_test targets generated by this extension.

Defaults to None

`browser_overrides`

Dictionary; optional; default is an empty dictionary. A dictionary mapping from browser names to browser-specific web_test attributes, such as shard_count, flakiness, timeout, etc. For example:

{
    '//browsers:chrome-native': {'shard_count': 3, 'flaky': 1},
    '//browsers:firefox-native': {'shard_count': 1, 'timeout': 100},
}

Defaults to None

`config`

Label; optional; Configuration of web test features.

Defaults to None

`flaky`

A boolean specifying that the test is flaky. If set, the test will be retried up to 3 times (default: 0)

Defaults to None

`local`

boolean; optional.

Defaults to None

`shard_count`

The number of test shards to use per browser. (default: 1)

Defaults to None

`size`

A string specifying the test size. (default: ‘large’)

Defaults to None

`tags`

A list of test tag strings to apply to each generated web_test target. This macro adds a couple for ibazel.

Defaults to []

`test_suite_tags`

A list of tag strings for the generated test_suite.

Defaults to None

`timeout`

A string specifying the test timeout (default: computed from size)

Defaults to None

`visibility`

List of labels; optional.

Defaults to None

`web_test_data`

Data dependencies for the web_test.

Defaults to []

`wrapped_test_tags`

A list of test tag strings to use for the wrapped test

Defaults to None

`remaining_keyword_args`

Arguments for the wrapped test target.

ts_web_test

This rule has been removed. Replace with karma_web_test

Usage

ts_web_test(kwargs)

`kwargs`

ts_web_test_suite

This rule has been removed. Replace with ts_web_test_suite

Usage

ts_web_test_suite(kwargs)