feat: port pytest_test macro

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

examples/pytest/BUILD.bazel

@@ -1,23 +1,15 @@
-load("@aspect_rules_py//py:defs.bzl", "py_pytest_main", "py_test")
+load("@aspect_rules_py//pytest:defs.bzl", "pytest_test")
 
-py_pytest_main(
-    name = "__test__",
-    deps = ["@pypi_pytest//:pkg"],
-)
-
-py_test(
+pytest_test(
     name = "pytest_test",
     srcs = [
         "foo_test.py",
-        ":__test__",
     ],
     imports = ["../.."],
-    main = ":__test__.py",
     package_collisions = "warning",
+    pip_repo = "pypi",
     deps = [
-        ":__test__",
         "@pypi_ftfy//:pkg",
         "@pypi_neptune//:pkg",
-        "@pypi_pytest//:pkg",
     ],
 )

py/defs.bzl

@@ -22,22 +22,26 @@ py_unpacked_wheel = _py_unpacked_wheel
 resolutions = _resolutions
 
 def _py_binary_or_test(name, rule, srcs, main, deps = [], resolutions = {}, **kwargs):
+    if type(main) not in ["string", "Label"]:
+        fail("main must be a Label or a string")
+
     # Compatibility with rules_python, see docs in py_executable.bzl
     main_target = "_{}.find_main".format(name)
-    determine_main(
-        name = main_target,
-        target_name = name,
-        main = main,
-        srcs = srcs,
-        **propagate_common_rule_attributes(kwargs)
-    )
+    if type(main) == "string":
+        determine_main(
+            name = main_target,
+            target_name = name,
+            main = main,
+            srcs = srcs,
+            **propagate_common_rule_attributes(kwargs)
+        )
 
     package_collisions = kwargs.pop("package_collisions", None)
 
     rule(
         name = name,
         srcs = srcs,
-        main = main_target,
+        main = main if type(main) == "Label" else main_target,
         deps = deps,
         resolutions = resolutions,
         package_collisions = package_collisions,

pytest/BUILD.bazel

@@ -0,0 +1,4 @@
+exports_files(
+    ["pytest_shim.py"],
+    visibility = ["//visibility:public"],
+)

pytest/defs.bzl

@@ -0,0 +1,65 @@
+"""Use pytest to run tests, using a wrapper script to interface with Bazel.
+
+Example:
+
+```starlark
+load("@aspect_rules_py//pytest:defs.bzl", "pytest_test")
+
+pytest_test(
+    name = "test_w_pytest",
+    size = "small",
+    srcs = ["test.py"],
+)
+```
+
+By default, `@pip//pytest` is added to `deps`.
+If sharding is used (when `shard_count > 1`) then `@pip//pytest_shard` is also added.
+To instead provide explicit deps for the pytest library, set `pytest_deps`:
+
+```starlark
+pytest_test(
+    name = "test_w_my_pytest",
+    shard_count = 2,
+    srcs = ["test.py"],
+    pytest_deps = [requirement("pytest"), requirement("pytest-shard"), ...],
+)
+```
+"""
+
+load("//py:defs.bzl", "py_test")
+
+def pytest_test(name, srcs, deps = [], args = [], pytest_deps = None, pip_repo = "pip", **kwargs):
+    """
+    Wrapper macro for `py_test` which supports pytest.
+
+    Args:
+      name: A unique name for this target.
+      srcs: Python source files.
+      deps: Dependencies, typically `py_library`.
+      args: Additional command-line arguments to pytest.
+        See https://docs.pytest.org/en/latest/how-to/usage.html
+      pytest_deps: Labels of the pytest tool and other packages it may import.
+      pip_repo: Name of the external repository where Python packages are installed.
+        It's typically created by `pip.parse`.
+        This attribute is used only when `pytest_deps` is unset.
+      **kwargs: Additional named parameters to py_test.
+    """
+    shim_label = Label("//pytest:pytest_shim.py")
+
+    if pytest_deps == None:
+        pytest_deps = ["@{}//pytest".format(pip_repo)]
+        if kwargs.get("shard_count", 1) > 1:
+            pytest_deps.append("@{}//pytest_shard".format(pip_repo))
+
+    py_test(
+        name = name,
+        srcs = [
+            shim_label,
+        ] + srcs,
+        main = shim_label,
+        args = [
+            "--capture=no",
+        ] + args + ["$(location :%s)" % x for x in srcs],
+        deps = deps + pytest_deps,
+        **kwargs
+    )

pytest/pytest_shim.py

@@ -0,0 +1,68 @@
+"""A shim for executing pytest that supports test filtering, sharding, and more."""
+
+import sys
+import os
+
+import pytest
+
+
+if __name__ == "__main__":
+    pytest_args = ["--ignore=external"]
+
+    args = sys.argv[1:]
+    # pytest < 8.0 runs tests twice if __init__.py is passed explicitly as an argument.
+    # Remove any __init__.py file to avoid that.
+    # pytest.version_tuple is available since pytest 7.0
+    # https://github.com/pytest-dev/pytest/issues/9313
+    if not hasattr(pytest, "version_tuple") or pytest.version_tuple < (8, 0):
+        args = [arg for arg in args if arg.startswith("-") or os.path.basename(arg) != "__init__.py"]
+
+    if os.environ.get("XML_OUTPUT_FILE"):
+        pytest_args.append("--junitxml={xml_output_file}".format(xml_output_file=os.environ.get("XML_OUTPUT_FILE")))
+
+    # Handle test sharding - requires pytest-shard plugin.
+    if os.environ.get("TEST_SHARD_INDEX") and os.environ.get("TEST_TOTAL_SHARDS"):
+        pytest_args.append("--shard-id={shard_id}".format(shard_id=os.environ.get("TEST_SHARD_INDEX")))
+        pytest_args.append("--num-shards={num_shards}".format(num_shards=os.environ.get("TEST_TOTAL_SHARDS")))
+        if os.environ.get("TEST_SHARD_STATUS_FILE"):
+            open(os.environ["TEST_SHARD_STATUS_FILE"], "a").close()
+
+    # Handle plugins that generate reports - if they are provided with relative paths (via args),
+    # re-write it under bazel's test undeclared outputs dir.
+    if os.environ.get("TEST_UNDECLARED_OUTPUTS_DIR"):
+        undeclared_output_dir = os.environ.get("TEST_UNDECLARED_OUTPUTS_DIR")
+
+        # Flags that take file paths as value.
+        path_flags = [
+            "--report-log",  # pytest-reportlog
+            "--json-report-file",  # pytest-json-report
+            "--html",  # pytest-html
+        ]
+        for i, arg in enumerate(args):
+            for flag in path_flags:
+                if arg.startswith(f"{flag}="):
+                    arg_split = arg.split("=", 1)
+                    if len(arg_split) == 2 and not os.path.isabs(arg_split[1]):
+                        args[i] = f"{flag}={undeclared_output_dir}/{arg_split[1]}"
+
+    if os.environ.get("TESTBRIDGE_TEST_ONLY"):
+        test_filter = os.environ["TESTBRIDGE_TEST_ONLY"]
+
+        # If the test filter does not start with a class-like name, then use test filtering instead
+        if not test_filter[0].isupper():
+            # --test_filter=test_module.test_fn or --test_filter=test_module/test_file.py
+            pytest_args.extend(args)
+            pytest_args.append("-k={filter}".format(filter=test_filter))
+        else:
+            # --test_filter=TestClass.test_fn
+            for arg in args:
+                if not arg.startswith("--"):
+                    # arg is a src file. Add test class/method selection to it.
+                    # test.py::TestClass::test_fn
+                    arg = "{arg}::{module_fn}".format(arg=arg, module_fn=test_filter.replace(".", "::"))
+                pytest_args.append(arg)
+    else:
+        pytest_args.extend(args)
+
+    print(pytest_args, file=sys.stderr)
+    raise SystemExit(pytest.main(pytest_args))