fix(transitions): correctly default 'main' arg for transition rules

aignas · aignas · commit 594610910ff0 · 2023-07-14T17:55:05.000+09:00
Before the change the version-aware py_binary and py_test rules would not default the 'main' argument correctly and this change adds unit tests and a helper function to do the defaulting. Work towards #1262
diff --git a/examples/multi_python_versions/tests/BUILD.bazel b/examples/multi_python_versions/tests/BUILD.bazel
@@ -1,13 +1,22 @@
+load("@bazel_skylib//rules:copy_file.bzl", "copy_file")
 load("@python//3.10:defs.bzl", py_binary_3_10 = "py_binary", py_test_3_10 = "py_test")
 load("@python//3.11:defs.bzl", py_binary_3_11 = "py_binary", py_test_3_11 = "py_test")
 load("@python//3.8:defs.bzl", py_binary_3_8 = "py_binary", py_test_3_8 = "py_test")
 load("@python//3.9:defs.bzl", py_binary_3_9 = "py_binary", py_test_3_9 = "py_test")
 load("@rules_python//python:defs.bzl", "py_binary", "py_test")
 
+copy_file(
+    name = "copy_version",
+    src = "version.py",
+    out = "version_default.py",
+    is_executable = True,
+)
+
+# NOTE: We are testing that the `main` is an optional param as per official
+# docs https://bazel.build/reference/be/python#py_binary.main
 py_binary(
     name = "version_default",
-    srcs = ["version.py"],
-    main = "version.py",
+    srcs = ["version_default.py"],
 )
 
 py_binary_3_8(
@@ -69,11 +78,17 @@ py_test_3_11(
     deps = ["//libs/my_lib"],
 )
 
+copy_file(
+    name = "copy_version_test",
+    src = "version_test.py",
+    out = "version_default_test.py",
+    is_executable = True,
+)
+
 py_test(
     name = "version_default_test",
-    srcs = ["version_test.py"],
+    srcs = ["version_default_test.py"],
     env = {"VERSION_CHECK": "3.9"},  # The default defined in the WORKSPACE.
-    main = "version_test.py",
 )
 
 py_test_3_8(
diff --git a/python/config_settings/private/BUILD.bazel b/python/config_settings/private/BUILD.bazel
diff --git a/python/config_settings/private/py_args.bzl b/python/config_settings/private/py_args.bzl
@@ -0,0 +1,40 @@
+# Copyright 2023 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"A helper to extract default args for the transition rule"
+
+def py_args(name, kwargs):
+    """A helper to extract common py_binary and py_test args
+
+    See https://bazel.build/reference/be/python#py_binary and
+    https://bazel.build/reference/be/python#py_test for the list
+    that should be returned
+
+    Args:
+        name: The name of the target.
+        kwargs: The kwargs to be extracted from.
+
+    Returns:
+        A dict with the extracted arguments
+    """
+    return dict(
+        args = kwargs.pop("args", None),
+        data = kwargs.pop("data", None),
+        env = kwargs.pop("env", None),
+        srcs = kwargs.pop("srcs", None),
+        deps = kwargs.pop("deps", None),
+        # See https://bazel.build/reference/be/python#py_binary.main
+        # for default logic.
+        main = kwargs.pop("main", name),
+    )
diff --git a/python/config_settings/transition.bzl b/python/config_settings/transition.bzl
@@ -18,6 +18,7 @@ them to the desired target platform.
 
 load("@bazel_skylib//lib:dicts.bzl", "dicts")
 load("//python:defs.bzl", _py_binary = "py_binary", _py_test = "py_test")
+load("//python/config_settings/private:py_args.bzl", "py_args")
 
 def _transition_python_version_impl(_, attr):
     return {"//python/config_settings:python_version": str(attr.python_version)}
@@ -138,11 +139,13 @@ _transition_py_test = rule(
 )
 
 def _py_rule(rule_impl, transition_rule, name, python_version, **kwargs):
-    args = kwargs.pop("args", None)
-    data = kwargs.pop("data", None)
-    env = kwargs.pop("env", None)
-    srcs = kwargs.pop("srcs", None)
-    deps = kwargs.pop("deps", None)
+    pyargs = py_args(name, kwargs)
+    args = pyargs["args"]
+    data = pyargs["data"]
+    env = pyargs["env"]
+    srcs = pyargs["srcs"]
+    deps = pyargs["deps"]
+    main = pyargs["main"]
 
     # Attributes common to all build rules.
     # https://bazel.build/reference/be/common-definitions#common-attributes
@@ -197,6 +200,7 @@ def _py_rule(rule_impl, transition_rule, name, python_version, **kwargs):
         deps = deps,
         env = env,
         srcs = srcs,
+        main = main,
         tags = ["manual"] + (tags if tags else []),
         visibility = ["//visibility:private"],
         **dicts.add(common_attrs, kwargs)
diff --git a/python/extensions/private/defs.bzl.tmpl b/python/extensions/private/defs.bzl.tmpl
@@ -0,0 +1,17 @@
+"""Defs required for entry_point transitions, for PRIVATE USE ONLY.
+
+@generated by rules_python pip.parse extension.
+
+We use this method as opposed handling it in whl_library definition
+because not everybody is using version-aware toolchains and doing that
+in whl_library may lead to a lot of code otherwise.
+"""
+
+load("@@%%RULES_PYTHON%%//python/config_settings:transition.bzl", _py_binary = "py_binary")
+
+def py_binary(name, **kwargs):
+    _py_binary(
+        name = name,
+        python_version = "%%FULL_VERSION%%",
+        **kwargs,
+    )
diff --git a/tests/config_settings/transition/BUILD.bazel b/tests/config_settings/transition/BUILD.bazel
@@ -0,0 +1,3 @@
+load(":py_args_tests.bzl", "py_args_test_suite")
+
+py_args_test_suite(name = "py_args_tests")
diff --git a/tests/config_settings/transition/py_args_tests.bzl b/tests/config_settings/transition/py_args_tests.bzl
@@ -0,0 +1,68 @@
+# Copyright 2023 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+""
+
+load("@rules_testing//lib:test_suite.bzl", "test_suite")
+load("//python/config_settings/private:py_args.bzl", "py_args")  # buildifier: disable=bzl-visibility
+
+_tests = []
+
+def _test_py_args_default(env):
+    actual = py_args("foo", {})
+
+    want = {
+        "args": None,
+        "data": None,
+        "deps": None,
+        "env": None,
+        "main": "foo",
+        "srcs": None,
+    }
+    env.expect.that_dict(actual).contains_exactly(want)
+
+_tests.append(_test_py_args_default)
+
+def _test_kwargs_get_consumed(env):
+    kwargs = {
+        "args": ["some", "args"],
+        "data": ["data"],
+        "deps": ["deps"],
+        "env": {"key": "value"},
+        "main": "__main__.py",
+        "srcs": ["__main__.py"],
+        "visibility": ["//visibility:public"],
+    }
+    actual = py_args("bar_bin", kwargs)
+
+    want = {
+        "args": ["some", "args"],
+        "data": ["data"],
+        "deps": ["deps"],
+        "env": {"key": "value"},
+        "main": "__main__.py",
+        "srcs": ["__main__.py"],
+    }
+    env.expect.that_dict(actual).contains_exactly(want)
+    env.expect.that_dict(kwargs).keys().contains_exactly(["visibility"])
+
+_tests.append(_test_kwargs_get_consumed)
+
+def py_args_test_suite(name):
+    """Create the test suite.
+
+    Args:
+        name: the name of the test suite
+    """
+    test_suite(name = name, basic_tests = _tests)

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+load(":py_args_tests.bzl", "py_args_test_suite")`
	`2`	`+`
	`3`	`+py_args_test_suite(name = "py_args_tests")`