Macros and Functions

Provide a sane default for *_test timeout attribute.

The test-encyclopedia says

Tests may return arbitrarily fast regardless of timeout. A test is not penalized for an overgenerous timeout, although a warning may be issued: you should generally set your timeout as tight as you can without incurring any flakiness.

However Bazel's default for timeout is medium, which is dumb given this guidance.

It also says:

Tests which do not explicitly specify a timeout have one implied based on the test's size as follows Therefore if size is specified, we should allow timeout to take its implied default. If neither is set, then we can fix Bazel's wrong default here to avoid warnings under --test_verbose_timeout_warnings.

This function can be used in a macro which wraps a testing rule.

the size attribute of a test target

the timeout attribute of a test target

Check whether a file exists.

Useful in macros to set defaults for a configuration file if it is present. This can only be called during the loading phase, not from a rule implementation.

a label, or a string which is a path relative to this package

Detects if the Bazel version being used is greater than or equal to 6 (including Bazel 6 pre-releases and RCs).

Detecting Bazel 6 or greater is particularly useful in rules as slightly different code paths may be needed to support bzlmod which was added in Bazel 6.

Unlike the undocumented native.bazel_version, which only works in WORKSPACE and repository rules, this function can be used in rules and BUILD files.

An alternate approach to make the Bazel version available in BUILD files and rules would be to use the host_repo repository rule which contains the bazel_version in the exported host struct:

WORKSPACE:

load("@aspect_bazel_lib//lib:host_repo.bzl", "host_repo")
host_repo(name = "aspect_bazel_lib_host")

BUILD.bazel:

load("@aspect_bazel_lib_host//:defs.bzl", "host")
print(host.bazel_version)

That approach, however, incurs a cost in the user's WORKSPACE.

Returns True if the given Label (or stringy version of a label) represents a target outside of the workspace

a string or label

Adapts a maybe(http_archive, ...) to look like an http_archive.

This makes WORKSPACE dependencies easier to read and update.

Typical usage looks like,

load("//lib:utils.bzl", http_archive = "maybe_http_archive")

http_archive(
    name = "aspect_rules_js",
    sha256 = "5bb643d9e119832a383e67f946dc752b6d719d66d1df9b46d840509ceb53e1f1",
    strip_prefix = "rules_js-1.6.2",
    url = "https://github.com/aspect-build/rules_js/archive/refs/tags/v1.6.2.tar.gz",
)

instead of the classic maybe pattern of,

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")

maybe(
    http_archive,
    name = "aspect_rules_js",
    sha256 = "5bb643d9e119832a383e67f946dc752b6d719d66d1df9b46d840509ceb53e1f1",
    strip_prefix = "rules_js-1.6.2",
    url = "https://github.com/aspect-build/rules_js/archive/refs/tags/v1.6.2.tar.gz",
)

all arguments to pass-forward to http_archive

Returns the path to the workspace root under bazel

Returns a list of tags filtered from the input set that only contains the ones that are considered "well known"

These are listed in Bazel's documentation: https://docs.bazel.build/versions/main/test-encyclopedia.html#tag-conventions https://docs.bazel.build/versions/main/be/common-definitions.html#common-attributes

List of tags to filter

Converts a string to a Label. If Label is supplied, the same label is returned.

a string representing a label or a Label