Create a licence_test rule

The `license_test` rule executes the licence checker as a bazel test
(rather than an executable), thus allowing an upstream project to
use the rule as part of a set of presubmit tests.

Signed-off-by: Chris Frantz <cfrantz@google.com>

Author: cfrantz

rules/licence-checker-runner.template.sh

@@ -3,8 +3,16 @@
 # Licensed under the Apache License, Version 2.0, see LICENSE for details.
 # SPDX-License-Identifier: Apache-2.0
 
-if ! cd "$BUILD_WORKSPACE_DIRECTORY"; then
-    echo "Unable to change to workspace (BUILD_WORKSPACE_DIRECTORY: ${BUILD_WORKSPACE_DIRECTORY})"
+WORKSPACE="@@WORKSPACE@@"
+
+if [[ ! -z "${WORKSPACE}" ]]; then
+    REPO="$(dirname "$(realpath ${WORKSPACE})")"
+    cd ${REPO} || exit 1
+elif [[ ! -z "${BUILD_WORKSPACE_DIRECTORY+is_set}" ]]; then
+    cd ${BUILD_WORKSPACE_DIRECTORY} || exit 1
+else
+    echo "Neither WORKSPACE nor BUILD_WORKSPACE_DIRECTORY were set."
+    echo "If this is a test rule, add 'workspace = \"//:WORKSPACE\"' to your rule."
     exit 1
 fi
 

rules/rules.bzl

@@ -17,7 +17,7 @@ def _licence_check_impl(ctx):
             substitutions = {
                 "@@LICENCE@@": "'''" + ctx.attr.licence + "'''",
                 "@@MATCH_REGEX@@": "true" if ctx.attr.match_regex else "false",
-                "@@EXCLUDE_PATHS@@": ', '.join(['"{}"'.format(pat) for pat in ctx.attr.exclude_patterns]),
+                "@@EXCLUDE_PATHS@@": ", ".join(['"{}"'.format(pat) for pat in ctx.attr.exclude_patterns]),
             },
         )
 
@@ -35,68 +35,94 @@ def _licence_check_impl(ctx):
         command = 'touch "{}"'.format(checker.path),
     )
 
+    workspace = ctx.file.workspace.path if ctx.file.workspace else ""
     script = ctx.actions.declare_file(ctx.label.name + ".bash")
     ctx.actions.expand_template(
         template = ctx.file._runner,
         output = script,
         substitutions = {
             "@@LICENCE_CHECKER@@": ctx.executable.licence_check.path,
             "@@CONFIG@@": config.path,
+            "@@WORKSPACE@@": workspace,
         },
         is_executable = True,
     )
 
-    runfiles = ctx.runfiles(files = [config, checker], transitive_files = ctx.attr.licence_check.files)
+    files = [config, checker]
+    if ctx.file.workspace:
+        files.append(ctx.file.workspace)
+
+    runfiles = ctx.runfiles(files = files, transitive_files = ctx.attr.licence_check.files)
     runfiles = runfiles.merge(
-      ctx.attr.licence_check.default_runfiles,
+        ctx.attr.licence_check.default_runfiles,
     )
 
     return DefaultInfo(
         runfiles = runfiles,
         executable = script,
     )
 
+licence_check_attrs = {
+    "config": attr.label(
+        allow_single_file = True,
+        doc = "HJSON configuration file override for the licence checker",
+    ),
+    "licence": attr.string(
+        mandatory = True,
+        doc = "Text of the licence header to use",
+    ),
+    "match_regex": attr.bool(
+        default = False,
+        doc = "Whether to use regex-matching for the licence text",
+    ),
+    "exclude_patterns": attr.string_list(
+        default = [],
+        doc = "File patterns to exclude from licence enforcement",
+    ),
+    "licence_check": attr.label(
+        default = "//licence-checker",
+        cfg = "host",
+        executable = True,
+        doc = "The licence checker executable",
+    ),
+    "workspace": attr.label(
+        allow_single_file = True,
+        doc = "Label of the WORKSPACE file",
+    ),
+    "_runner": attr.label(
+        default = "//rules:licence-checker-runner.template.sh",
+        allow_single_file = True,
+    ),
+    "_config": attr.label(
+        default = "//rules:licence-checker-config.template.hjson",
+        allow_single_file = True,
+    ),
+}
+
 licence_check = rule(
     implementation = _licence_check_impl,
-    attrs = {
-        "config": attr.label(
-            allow_single_file = True,
-            doc = "HJSON configuration file override for the licence checker",
-        ),
-        "licence": attr.string(
-            mandatory = True,
-            doc = "Text of the licence header to use",
-        ),
-        "match_regex": attr.bool(
-            default = False,
-            doc = "Whether to use regex-matching for the licence text",
-        ),
-        "exclude_patterns": attr.string_list(
-            default = [],
-            doc = "File patterns to exclude from licence enforcement",
-        ),
-        "licence_check": attr.label(
-            default = "//licence-checker",
-            cfg = "host",
-            executable = True,
-            doc = "The licence checker executable",
-        ),
-        "_runner": attr.label(
-            default = "//rules:licence-checker-runner.template.sh",
-            allow_single_file = True,
-        ),
-        "_config": attr.label(
-            default = "//rules:licence-checker-config.template.hjson",
-            allow_single_file = True,
-        ),
-        "_sh_runfiles": attr.label(
-            default = "@bazel_tools//tools/bash/runfiles",
-            allow_single_file = True,
-        ),
-    },
+    attrs = licence_check_attrs,
     executable = True,
 )
 
+_licence_test = rule(
+    implementation = _licence_check_impl,
+    attrs = licence_check_attrs,
+    test = True,
+)
+
+def _ensure_tag(tags, *tag):
+    for t in tag:
+        if t not in tags:
+            tags.append(t)
+    return tags
+
+def licence_test(**kwargs):
+    # Note: the "external" tag is a workaround for bazelbuild#15516.
+    tags = kwargs.get("tags", [])
+    kwargs["tags"] = _ensure_tag(tags, "no-sandbox", "no-cache", "external")
+    _licence_test(**kwargs)
+
 def _yapf_check_impl(ctx):
     # Hack to make Bazel build the checker correctly.
     #
@@ -173,4 +199,3 @@ yapf_check = rule(
     },
     executable = True,
 )
-