feat: implement bats test runner (#699)

MODULE.bazel

@@ -22,7 +22,8 @@ bazel_lib_toolchains.yq()
 bazel_lib_toolchains.coreutils()
 bazel_lib_toolchains.tar()
 bazel_lib_toolchains.expand_template()
-use_repo(bazel_lib_toolchains, "bsd_tar_toolchains", "copy_directory_toolchains", "copy_to_directory_toolchains", "coreutils_toolchains", "expand_template_toolchains", "jq_toolchains", "yq_toolchains")
+bazel_lib_toolchains.bats()
+use_repo(bazel_lib_toolchains, "bats_toolchains", "bsd_tar_toolchains", "copy_directory_toolchains", "copy_to_directory_toolchains", "coreutils_toolchains", "expand_template_toolchains", "jq_toolchains", "yq_toolchains")
 
 register_toolchains(
     "@copy_directory_toolchains//:all",
@@ -31,6 +32,7 @@ register_toolchains(
     "@yq_toolchains//:all",
     "@coreutils_toolchains//:all",
     "@expand_template_toolchains//:all",
+    "@bats_toolchains//:all",
     # Expand bsd_tar_toolchains
     "@bsd_tar_toolchains//:linux_amd64_toolchain",
     "@bsd_tar_toolchains//:linux_arm64_toolchain",

docs/BUILD.bazel

@@ -151,4 +151,9 @@ stardoc_with_diff_test(
     bzl_library_target = "//lib:strings",
 )
 
+stardoc_with_diff_test(
+    name = "bats",
+    bzl_library_target = "//lib:bats",
+)
+
 update_docs()

e2e/smoke/BUILD.bazel

@@ -1,3 +1,4 @@
+load("@aspect_bazel_lib//lib:bats.bzl", "bats_test")
 load("@aspect_bazel_lib//lib:copy_directory.bzl", "copy_directory")
 load("@aspect_bazel_lib//lib:copy_to_directory.bzl", "copy_to_directory")
 load("@aspect_bazel_lib//lib:diff_test.bzl", "diff_test")
@@ -91,3 +92,10 @@ tar(
     srcs = [],
     mtree = [],
 )
+
+bats_test(
+    name = "bats",
+    srcs = [
+        "basic.bats",
+    ],
+)

e2e/smoke/basic.bats

@@ -0,0 +1,8 @@
+bats_load_library "bats-support"
+bats_load_library "bats-assert"
+
+@test 'basic' {
+    run echo 'have'
+    assert_output 'have'
+}
+

internal_deps.bzl

@@ -4,7 +4,7 @@ Users should *not* need to install these. If users see a load()
 statement from these, that's a bug in our distribution.
 """
 
-load("//lib:repositories.bzl", "register_coreutils_toolchains", "register_jq_toolchains", "register_tar_toolchains", "register_yq_toolchains")
+load("//lib:repositories.bzl", "register_bats_toolchains", "register_coreutils_toolchains", "register_jq_toolchains", "register_tar_toolchains", "register_yq_toolchains")
 load("//lib:utils.bzl", http_archive = "maybe_http_archive")
 
 # buildifier: disable=unnamed-macro
@@ -72,3 +72,6 @@ def bazel_lib_internal_deps():
     register_yq_toolchains()
     register_coreutils_toolchains()
     register_tar_toolchains()
+    register_bats_toolchains(
+        libraries = ["@aspect_bazel_lib//lib/tests/bats/bats-custom:custom"],
+    )

lib/BUILD.bazel

@@ -59,11 +59,16 @@ toolchain_type(
     name = "tar_toolchain_type",
 )
 
+toolchain_type(
+    name = "bats_toolchain_type",
+)
+
 bzl_library(
     name = "expand_make_vars",
     srcs = ["expand_make_vars.bzl"],
     deps = [
-        ":expand_template",
+        "//lib/private:expand_locations",
+        "//lib/private:expand_variables",
     ],
 )
 
@@ -235,6 +240,7 @@ bzl_library(
     srcs = ["repositories.bzl"],
     deps = [
         ":utils",
+        "//lib/private:bats_toolchain",
         "//lib/private:copy_directory_toolchain",
         "//lib/private:copy_to_directory_toolchain",
         "//lib/private:coreutils_toolchain",
@@ -295,3 +301,9 @@ bzl_library(
     srcs = ["windows_utils.bzl"],
     deps = ["//lib/private:paths"],
 )
+
+bzl_library(
+    name = "bats",
+    srcs = ["bats.bzl"],
+    deps = ["//lib/private:bats"],
+)

lib/bats.bzl

@@ -0,0 +1,5 @@
+"Bats test runner"
+
+load("//lib/private:bats.bzl", _bats_test = "bats_test")
+
+bats_test = _bats_test

lib/extensions.bzl

@@ -2,6 +2,8 @@
 
 load(
     "@aspect_bazel_lib//lib:repositories.bzl",
+    "DEFAULT_BATS_CORE_VERSION",
+    "DEFAULT_BATS_REPOSITORY",
     "DEFAULT_COPY_DIRECTORY_REPOSITORY",
     "DEFAULT_COPY_TO_DIRECTORY_REPOSITORY",
     "DEFAULT_COREUTILS_REPOSITORY",
@@ -12,6 +14,7 @@ load(
     "DEFAULT_TAR_REPOSITORY",
     "DEFAULT_YQ_REPOSITORY",
     "DEFAULT_YQ_VERSION",
+    "register_bats_toolchains",
     "register_copy_directory_toolchains",
     "register_copy_to_directory_toolchains",
     "register_coreutils_toolchains",
@@ -94,6 +97,15 @@ def _toolchains_extension_impl(mctx):
         get_version_fn = lambda attr: None,
     )
 
+    extension_utils.toolchain_repos_bfs(
+        mctx = mctx,
+        get_tag_fn = lambda tags: tags.bats,
+        toolchain_name = "bats",
+        default_repository = DEFAULT_BATS_REPOSITORY,
+        toolchain_repos_fn = lambda name, version: register_bats_toolchains(name = name, core_version = version, register = False),
+        get_version_fn = lambda attr: attr.core_version,
+    )
+
 toolchains = module_extension(
     implementation = _toolchains_extension_impl,
     tag_classes = {
@@ -104,5 +116,9 @@ toolchains = module_extension(
         "coreutils": tag_class(attrs = {"name": attr.string(default = DEFAULT_COREUTILS_REPOSITORY), "version": attr.string(default = DEFAULT_COREUTILS_VERSION)}),
         "tar": tag_class(attrs = {"name": attr.string(default = DEFAULT_TAR_REPOSITORY)}),
         "expand_template": tag_class(attrs = {"name": attr.string(default = DEFAULT_EXPAND_TEMPLATE_REPOSITORY)}),
+        "bats": tag_class(attrs = {
+            "name": attr.string(default = DEFAULT_BATS_REPOSITORY),
+            "core_version": attr.string(default = DEFAULT_BATS_CORE_VERSION),
+        }),
     },
 )

lib/private/BUILD.bazel

@@ -274,6 +274,23 @@ bzl_library(
     deps = ["@aspect_bazel_lib//lib:paths"],
 )
 
+bzl_library(
+    name = "bats",
+    srcs = ["bats.bzl"],
+    visibility = ["//lib:__subpackages__"],
+    deps = [
+        ":expand_locations",
+        ":expand_variables",
+        "@aspect_bazel_lib//lib:paths",
+    ],
+)
+
+bzl_library(
+    name = "bats_toolchain",
+    srcs = ["bats_toolchain.bzl"],
+    visibility = ["//lib:__subpackages__"],
+)
+
 bzl_library(
     name = "copy_common",
     srcs = ["copy_common.bzl"],

lib/private/bats.bzl

@@ -0,0 +1,90 @@
+"bats_test"
+
+load("//lib:paths.bzl", "BASH_RLOCATION_FUNCTION", "to_rlocation_path")
+load(":expand_locations.bzl", "expand_locations")
+load(":expand_variables.bzl", "expand_variables")
+
+_RUNNER_TMPL = """#!/usr/bin/env bash
+set -o errexit -o nounset -o pipefail
+
+{BASH_RLOCATION_FUNCTION}
+
+readonly core_path="$(rlocation {core})"
+readonly bats="$core_path/bin/bats"
+readonly libs=( {libraries} )
+
+{envs}
+
+NEW_LIBS=()
+for lib in "${{libs[@]}}"; do
+    NEW_LIBS+=( $(cd "$(rlocation $lib)/.." && pwd) )
+done
+
+export BATS_LIB_PATH=$(
+    IFS=:
+    echo "${{NEW_LIBS[*]}}"
+)
+export BATS_TEST_TIMEOUT="$TEST_TIMEOUT"
+export BATS_TMPDIR="$TEST_TMPDIR"
+
+exec $bats {tests} $@
+"""
+
+_ENV_SET = """export {var}=\"{value}\""""
+
+def _bats_test_impl(ctx):
+    toolchain = ctx.toolchains["@aspect_bazel_lib//lib:bats_toolchain_type"]
+    batsinfo = toolchain.batsinfo
+
+    envs = []
+    for (key, value) in ctx.attr.env.items():
+        envs.append(_ENV_SET.format(
+            var = key,
+            value = " ".join([expand_variables(ctx, exp, attribute_name = "env") for exp in expand_locations(ctx, value, ctx.attr.data).split(" ")]),
+        ))
+
+    runner = ctx.actions.declare_file("%s_bats.sh" % ctx.label.name)
+    ctx.actions.write(
+        output = runner,
+        content = _RUNNER_TMPL.format(
+            core = to_rlocation_path(ctx, batsinfo.core),
+            libraries = " ".join([to_rlocation_path(ctx, lib) for lib in batsinfo.libraries]),
+            tests = " ".join([test.short_path for test in ctx.files.srcs]),
+            envs = "\n".join(envs),
+            BASH_RLOCATION_FUNCTION = BASH_RLOCATION_FUNCTION,
+        ),
+        is_executable = True,
+    )
+
+    runfiles = ctx.runfiles(ctx.files.srcs + ctx.files.data)
+    runfiles = runfiles.merge(toolchain.default.default_runfiles)
+    runfiles = runfiles.merge(ctx.attr._runfiles.default_runfiles)
+
+    return DefaultInfo(
+        executable = runner,
+        runfiles = runfiles,
+    )
+
+bats_test = rule(
+    implementation = _bats_test_impl,
+    attrs = {
+        "srcs": attr.label_list(
+            allow_files = [".bats"],
+            doc = "Test files",
+        ),
+        "data": attr.label_list(
+            allow_files = True,
+            doc = "Runtime dependencies of the test.",
+        ),
+        "env": attr.string_dict(
+            doc = """Environment variables of the action.
+
+            Subject to [$(location)](https://bazel.build/reference/be/make-variables#predefined_label_variables)
+            and ["Make variable"](https://bazel.build/reference/be/make-variables) substitution.
+            """,
+        ),
+        "_runfiles": attr.label(default = "@bazel_tools//tools/bash/runfiles"),
+    },
+    toolchains = ["@aspect_bazel_lib//lib:bats_toolchain_type"],
+    test = True,
+)