refactor(tools): migrate private release tool tests to pytest and pytest-mock (#3937)

Migrates release tool unit tests under `tests/tools/private/release/` to
Pytest and Pytest-mock (`mocker` fixture).

- Added `pytest-mock` dependency to `docs/pyproject.toml`, updated
`docs/uv.lock` & `docs/requirements.txt`, and added `@pypi//pytest_mock`
to release test helper `deps`.
- Converted release test targets from standard unittest to pytest
fixtures.
- Refactored tests to use the standard `mocker` fixture from
`pytest-mock`.

Author: rickeylev

AGENTS.md

@@ -42,6 +42,14 @@ because it interferes with code review comments.
 Follow the advice in `CONTRIBUTING.md` for PR descriptions. PR descriptions
 become the commit message upon merge.
 
+### Python pytest conventions
+
+* When registering pytest fixtures from helper modules in test files, use
+  `pytest_plugins = ["<module_path>"]`.
+* Name fixture functions with a `fixture_` prefix (e.g. `def fixture_foo():`),
+  and pass the public fixture name using the `name` parameter in
+  `@pytest.fixture(name="foo")`.
+
 ### Starlark style
 
 For doc strings, using triple quoted strings when the doc string is more than
@@ -98,7 +106,6 @@ def foo_test_suite(name):
     test_suite(name=name, tests=_tests)
 ```
 
-
 #### Repository rules
 
 The function argument `rctx` is a hint that the function is a repository rule,
@@ -157,7 +164,6 @@ This repository contains 3 Bazel bzlmod modules.
 
 `tests/support/` contains utility code and helpers for testing.
 
-
 `python/config_settings/BUILD.bazel` contains build flags that are part of the
 public API. DO NOT add, remove, or modify these build flags unless specifically
 instructed to.

docs/pyproject.toml

@@ -19,4 +19,5 @@ dependencies = [
     "markupsafe",
     "pytest",
     "pytest-bazel",
+    "pytest-mock",
 ]

docs/requirements.txt

@@ -309,9 +309,9 @@ myst-parser==3.0.1 ; python_full_version < '3.10' \
     --hash=sha256:6457aaa33a5d474aca678b8ead9b3dc298e89c68e67012e73146ea6fd54babf1 \
     --hash=sha256:88f0cb406cb363b077d176b51c476f62d60604d68a8dcdf4832e080441301a87
     # via rules-python-docs (docs/pyproject.toml)
-myst-parser==5.1.0 ; python_full_version == '3.10.*' \
-    --hash=sha256:9c91c52b3cdb4d94a6506e4fab4e2f296c7623a0da0dcbe6de1565c3dad67a8a \
-    --hash=sha256:ab69322dc6719dcc7f296479dbb70181b66df6ed315064f92dbc85c0e1bf2f02
+myst-parser==4.0.1 ; python_full_version == '3.10.*' \
+    --hash=sha256:5cfea715e4f3574138aecbf7d54132296bfd72bb614d31168f48c477a830a7c4 \
+    --hash=sha256:9134e88959ec3b5780aedf8a99680ea242869d012e8821db3126d427edc9c95d
     # via rules-python-docs (docs/pyproject.toml)
 myst-parser==5.1.0 ; python_full_version >= '3.11' \
     --hash=sha256:9c91c52b3cdb4d94a6506e4fab4e2f296c7623a0da0dcbe6de1565c3dad67a8a \
@@ -352,15 +352,21 @@ pytest==8.4.2 ; python_full_version < '3.10' \
     # via
     #   rules-python-docs (docs/pyproject.toml)
     #   pytest-bazel
+    #   pytest-mock
 pytest==9.1.1 ; python_full_version >= '3.10' \
     --hash=sha256:1088fbde8f2b49d95a549a195707afa7a76a3ce9bcadc26b6d71f0ffda5fe313 \
     --hash=sha256:37a86b45efb9a47a61a36449063e8e18d0cab3161329fc099eb21783169c4f0c
     # via
     #   rules-python-docs (docs/pyproject.toml)
     #   pytest-bazel
+    #   pytest-mock
 pytest-bazel==0.1.6 \
     --hash=sha256:a29e80e1d67c3db801bdd4d0b6b742f2bfb48cd6841caa33401458e5c4e29c21
     # via rules-python-docs (docs/pyproject.toml)
+pytest-mock==3.15.1 \
+    --hash=sha256:0a25e2eb88fe5168d535041d09a4529a188176ae608a6d249ee65abc0949630d \
+    --hash=sha256:1849a238f6f396da19762269de72cb1814ab44416fa73a8686deac10b0d87a0f
+    # via rules-python-docs (docs/pyproject.toml)
 pyyaml==6.0.3 \
     --hash=sha256:00c4bdeba853cc34e7dd471f16b4114f4162dc03e6b7afcc2128711f0eca823c \
     --hash=sha256:0150219816b6a1fa26fb4699fb7daa9caf09eb1999f3b70fb6e786805e80375a \

docs/uv.lock

@@ -1,149 +1,172 @@
-load("@rules_python//python:defs.bzl", "py_library", "py_test")
+load("//python:py_library.bzl", "py_library")
+load("//tests/support:support.bzl", "SUPPORTS_BZLMOD")
+load("//tests/support/pytest_test:pytest_test.bzl", "pytest_test")
 
 py_library(
     name = "release_test_helper",
     srcs = ["release_test_helper.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
         "//tools/private/release:mock_gh",
         "//tools/private/release:release_lib",
+        "@pypi//pytest_mock",
     ],
 )
 
-py_test(
+pytest_test(
     name = "add_backports_test",
     srcs = ["add_backports_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
         ":release_test_helper",
         "//tools/private/release:release_lib",
     ],
 )
 
-py_test(
+pytest_test(
     name = "changelog_news_test",
     srcs = ["changelog_news_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
         ":release_test_helper",
         "//tools/private/release:release_lib",
     ],
 )
 
-py_test(
+pytest_test(
     name = "complete_sync_changelog_test",
     srcs = ["complete_sync_changelog_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
         ":release_test_helper",
         "//tools/private/release:release_lib",
     ],
 )
 
-py_test(
-    name = "create_rc_test",
-    srcs = ["create_rc_test.py"],
+pytest_test(
+    name = "create_release_branch_test",
+    srcs = ["create_release_branch_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
         ":release_test_helper",
         "//tools/private/release:release_lib",
     ],
 )
 
-py_test(
-    name = "create_release_branch_test",
-    srcs = ["create_release_branch_test.py"],
+pytest_test(
+    name = "git_test",
+    srcs = ["git_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
         ":release_test_helper",
         "//tools/private/release:release_lib",
     ],
 )
 
-py_test(
-    name = "gh_test",
-    srcs = ["gh_test.py"],
+pytest_test(
+    name = "on_pr_merged_test",
+    srcs = ["on_pr_merged_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
+        ":release_test_helper",
         "//tools/private/release:release_lib",
     ],
 )
 
-py_test(
-    name = "git_test",
-    srcs = ["git_test.py"],
+pytest_test(
+    name = "promote_test",
+    srcs = ["promote_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
+        ":release_test_helper",
         "//tools/private/release:release_lib",
     ],
 )
 
-py_test(
-    name = "on_pr_merged_test",
-    srcs = ["on_pr_merged_test.py"],
+pytest_test(
+    name = "release_issue_test",
+    srcs = ["release_issue_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
         ":release_test_helper",
         "//tools/private/release:release_lib",
     ],
 )
 
-py_test(
-    name = "prepare_test",
-    srcs = ["prepare_test.py"],
+pytest_test(
+    name = "release_test",
+    srcs = ["release_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
         ":release_test_helper",
         "//tools/private/release:release_lib",
     ],
 )
 
-py_test(
-    name = "process_backports_test",
-    srcs = ["process_backports_test.py"],
+pytest_test(
+    name = "backport_create_releases_test",
+    srcs = ["backport_create_releases_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
         ":release_test_helper",
         "//tools/private/release:release_lib",
     ],
 )
 
-py_test(
-    name = "promote_test",
-    srcs = ["promote_test.py"],
+pytest_test(
+    name = "prepare_test",
+    srcs = ["prepare_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
         ":release_test_helper",
         "//tools/private/release:release_lib",
     ],
 )
 
-py_test(
-    name = "release_issue_test",
-    srcs = ["release_issue_test.py"],
+pytest_test(
+    name = "gh_test",
+    srcs = ["gh_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
+        ":release_test_helper",
         "//tools/private/release:release_lib",
     ],
 )
 
-py_test(
-    name = "release_test",
-    srcs = ["release_test.py"],
+pytest_test(
+    name = "backport_prepare_test",
+    srcs = ["backport_prepare_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
+        ":release_test_helper",
         "//tools/private/release:release_lib",
     ],
 )
 
-py_test(
-    name = "utils_test",
-    srcs = ["utils_test.py"],
+pytest_test(
+    name = "process_backports_test",
+    srcs = ["process_backports_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
         ":release_test_helper",
         "//tools/private/release:release_lib",
-        "@dev_pip//packaging",
     ],
 )
 
-py_test(
-    name = "backport_prepare_test",
-    srcs = ["backport_prepare_test.py"],
+pytest_test(
+    name = "create_rc_test",
+    srcs = ["create_rc_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
         ":release_test_helper",
         "//tools/private/release:release_lib",
     ],
 )
 
-py_test(
-    name = "backport_create_releases_test",
-    srcs = ["backport_create_releases_test.py"],
+pytest_test(
+    name = "utils_test",
+    srcs = ["utils_test.py"],
+    target_compatible_with = SUPPORTS_BZLMOD,
     deps = [
         ":release_test_helper",
         "//tools/private/release:release_lib",