Karma rules for Bazel

The Karma rules run karma tests with Bazel.

Installation

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

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

# Fetch transitive Bazel dependencies of @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", "web_test_repositories")

web_test_repositories()

load("@io_bazel_rules_webtesting//web/versioned:browsers-0.3.2.bzl", "browser_repositories")

browser_repositories(
    chromium = True,
    firefox = 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

USAGE

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

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.

By default we open a headless Chrome. To use a real Chrome browser window, you can pass --define DISPLAY=true to Bazel, along with configuration_env_vars = ["DISPLAY"] on karma_web_test.

PARAMETERS

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 []

peer_deps

list of peer npm deps required by karma_web_test

Defaults to ["@npm//jasmine-core", "@npm//karma", "@npm//karma-chrome-launcher", "@npm//karma-firefox-launcher", "@npm//karma-jasmine", "@npm//karma-requirejs", "@npm//karma-sourcemap-loader", "@npm//requirejs"]

kwargs

Passed through to karma_web_test

karma_web_test_suite

USAGE

karma_web_test_suite(name, browsers, web_test_data, wrapped_test_tags, kwargs)

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

This macro accepts all parameters in karma_web_test and adds additional parameters for the suite. See karma_web_test docs for all karma_web_test.

The wrapping macro is web_test_suite which comes from rules_websting: https://github.com/bazelbuild/rules_webtesting/blob/master/web/web.bzl.

PARAMETERS

name

The base name of the test

browsers

A sequence of labels specifying the browsers to use.

Defaults to None

web_test_data

Data dependencies for the wrapper web_test targets.

Defaults to []

wrapped_test_tags

A list of test tag strings to use for the wrapped karma_web_test target.

Defaults to ["manual", "noci"]

kwargs

Arguments for the wrapped karma_web_test target.