feat: port pytest_test macro (#401)

Comes from
caseyduquettesc/rules_python_pytest#13 It's much
easier to properly gazelle-generate a BUILD file in this shape rather
than the awkward way you're forced to hold our py_pytest_main.

Author: alexeagle

docs/py_test.md

@@ -1,4 +1,4 @@
-load("@aspect_rules_py//py:defs.bzl", "py_binary", "py_pytest_main", "py_test")
+load("@aspect_rules_py//py:defs.bzl", "py_binary", "py_test")
 
 py_binary(
     name = "main",
@@ -9,25 +9,14 @@ py_binary(
     main = "__main__.py",
 )
 
-# TODO(alex): land https://github.com/aspect-build/rules_py/pull/401 and shorten this
-py_pytest_main(
-    name = "__test__",
-    data = ["//:.coveragerc"],
-    deps = [
-        "@pip//coverage",
-        "@pip//pytest",
-    ],
-)
-
 py_test(
     name = "test",
-    srcs = [
-        "my_test.py",
-        ":__test__",
-    ],
-    main = ":__test__.py",
+    srcs = ["my_test.py"],
+    data = ["//:.coveragerc"],
+    pytest_main = True,
     deps = [
-        ":__test__",
         ":main",
+        "@pip//coverage",  # keep
+        "@pip//pytest",  # keep
     ],
 )

e2e/use_release/src/BUILD.bazel

@@ -1,75 +1,37 @@
-load("@aspect_rules_py//py:defs.bzl", "py_library", "py_pytest_main", "py_test")
+load("@aspect_rules_py//py:defs.bzl", "py_library", "py_test")
 
 py_library(
     name = "lib",
     srcs = ["foo.py"],
     imports = ["../.."],
 )
 
-py_pytest_main(
-    name = "__test__",
-    chdir = package_name(),  # So that test fixtures are available at the correct path
-    deps = [
-        "@pypi_coverage//:pkg",
-        "@pypi_pytest//:pkg",
-    ],
-)
-
 py_test(
     name = "pytest_test",
-    srcs = [
-        "foo_test.py",
-        ":__test__",
-    ],
+    srcs = ["foo_test.py"],
     data = glob([
         "fixtures/*.json",
     ]),
     env_inherit = ["FOO"],
     imports = ["../.."],
-    main = ":__test__.py",
     package_collisions = "warning",
+    pytest_main = True,
     deps = [
-        ":__test__",
-        ":lib",
-        "@pypi_ftfy//:pkg",
-        "@pypi_neptune//:pkg",
-        "@pypi_pytest//:pkg",
-    ],
-)
-
-py_test(
-    name = "nested/pytest",
-    srcs = [
-        "foo_test.py",
-        ":__test__",
-    ],
-    data = glob([
-        "fixtures/*.json",
-    ]),
-    env_inherit = ["FOO"],
-    imports = ["../.."],
-    main = ":__test__.py",
-    package_collisions = "warning",
-    deps = [
-        ":__test__",
         ":lib",
+        "@pypi_coverage//:pkg",
         "@pypi_ftfy//:pkg",
         "@pypi_neptune//:pkg",
         "@pypi_pytest//:pkg",
     ],
 )
 
 py_test(
-    name = "sharding_test",
-    srcs = [
-        "__test__.py",
-        "sharding_test.py",
-    ],
+    # NB: name contains a slash as regression test for #483
+    name = "sharded/test",
+    srcs = ["sharding_test.py"],
     imports = ["../.."],
-    main = "__test__.py",
     package_collisions = "warning",
+    pytest_main = True,
     shard_count = 2,
-    deps = [
-        "__test__",
-    ],
+    deps = ["@pypi_pytest//:pkg"],
 )

examples/pytest/BUILD.bazel

@@ -1,12 +1,14 @@
-import pytest
 import json
 
+import os
+
 from examples.pytest.foo import add
 
 def test_add():
     assert add(1, 1) == 2, "Expected 1 + 1 to equal 2"
 
 def test_hello_json():
-    content = open('fixtures/hello.json', 'r').read()
+    # NB: we don't use the chdir attribute so the test working directory is the repository root
+    content = open(os.path.join(os.getenv('TEST_TARGET').lstrip('/').split(':')[0], 'fixtures/hello.json'), 'r').read()
     data = json.loads(content)
     assert data["message"] == "Hello, world.", "Message is as expected"

examples/pytest/foo_test.py

@@ -117,7 +117,7 @@ def py_binary(name, srcs = [], main = None, **kwargs):
 
     _py_binary_or_test(name = name, rule = _py_binary, srcs = srcs, main = main, resolutions = resolutions, **kwargs)
 
-def py_test(name, srcs = [], main = None, **kwargs):
+def py_test(name, srcs = [], main = None, pytest_main = False, **kwargs):
     """Identical to [py_binary](./py_binary.md), but produces a target that can be used with `bazel test`.
 
     Args:
@@ -127,6 +127,8 @@ def py_test(name, srcs = [], main = None, **kwargs):
             Like rules_python, this is treated as a suffix of a file that should appear among the srcs.
             If absent, then `[name].py` is tried. As a final fallback, if the srcs has a single file,
             that is used as the main.
+        pytest_main: If set, generate a [py_pytest_main](#py_pytest_main) script and use it as the main.
+            The deps should include the pytest package (as well as the coverage package if desired).
         **kwargs: additional named parameters to `py_binary_rule`.
     """
 
@@ -139,4 +141,14 @@ def py_test(name, srcs = [], main = None, **kwargs):
     if resolutions:
         resolutions = resolutions.to_label_keyed_dict()
 
-    _py_binary_or_test(name = name, rule = _py_test, srcs = srcs, main = main, resolutions = resolutions, **kwargs)
+    deps = kwargs.pop("deps", [])
+    if pytest_main:
+        if main:
+            fail("When pytest_main is set, the main attribute should not be set.")
+        pytest_main_target = name + ".pytest_main"
+        main = pytest_main_target + ".py"
+        py_pytest_main(name = pytest_main_target)
+        srcs.append(main)
+        deps.append(pytest_main_target)
+
+    _py_binary_or_test(name = name, rule = _py_test, srcs = srcs, deps = deps, main = main, resolutions = resolutions, **kwargs)

py/defs.bzl

@@ -17,7 +17,12 @@ import os
 from pathlib import Path
 from typing import List
 
-import pytest
+try:
+    import pytest
+except ModuleNotFoundError as e:
+    print("ERROR: pytest must be included in the deps of the py_pytest_main or py_test target")
+    raise e
+
 # None means coverage wasn't enabled
 cov = None
 # For workaround of https://github.com/nedbat/coveragepy/issues/963
@@ -37,7 +42,7 @@ if "COVERAGE_MANIFEST" in os.environ:
             coveragepy_absfile_mapping = {coverage.files.abs_file(mfe): mfe for mfe in manifest_entries}
         cov.start()
     except ModuleNotFoundError as e:
-        print("WARNING: python coverage setup failed. Do you need to include the 'coverage' library as a dependency of py_pytest_main?", e)
+        print("WARNING: python coverage setup failed. Do you need to include the 'coverage' package as a dependency of py_pytest_main?", e)
         pass
 
 from pytest_shard import ShardPlugin