chore(deps): add PyYAML to the test extra (#1076)

pyproject.toml

@@ -333,6 +333,13 @@ test = [
     # failure: it names the file and prints the diff, where the skip it replaced
     # said nothing at all.
     "isort",
+    # The second opinion on the hand-rolled YAML scanners: the ``yaml.safe_load``
+    # cross-checks in ``tests/project/test_project_status.py``,
+    # ``test_release_gates.py``, ``test_bump_version.py`` and
+    # ``test_workflow_apt_timeouts.py`` skip without it.
+    # Test-only, as ``pcapkit`` never imports ``yaml``. Unpinned, since
+    # ``safe_load`` is all they use.
+    "PyYAML",
 ]
 
 # setuptools specific

tests/project/test_bump_version.py

@@ -226,7 +226,7 @@ def test_the_rewritten_date_is_a_string_and_not_a_yaml_date(self) -> None:
         try:
             import yaml
         except ImportError:  # pragma: no cover
-            self.skipTest('PyYAML is not in the test extra; the textual form is '
+            self.skipTest('PyYAML, from the test extra, is not installed; the textual form is '
                           'asserted by test_the_release_date_moves_with_the_version')
 
         rewritten = bump_version.plan_citation(FIXTURE, '1.5.0b5', '2026-09-22')

tests/project/test_release_gates.py

@@ -47,9 +47,9 @@
   since #887 removed their required reviewers. The question would resurface
   only if a matrix job were gated by its own environment again.
 
-:mod:`yaml` is not in the ``test`` extra, so the scanner in this module is
+:mod:`yaml` comes only with the ``test`` extra, so the scanner in this module is
 hand-rolled and dependency-free, and :class:`TestYAMLAgreesWithTheScanner` checks
-it against :func:`yaml.safe_load` only when PyYAML happens to be installed. The
+it against :func:`yaml.safe_load`, skipping on an install without that extra. The
 same split as ``test_the_rewritten_date_is_a_string_and_not_a_yaml_date`` in
 :file:`tests/project/test_bump_version.py`: the assertion that must run everywhere
 does not need the dependency, and the one that needs it guards the substitute.
@@ -240,7 +240,7 @@ def job_blocks(text: 'str') -> 'dict[str, str]':
     """``{job name: the job's own lines}`` for a workflow's top-level ``jobs:``.
 
     Indentation-based rather than a YAML parse, so that this module keeps working
-    on a fresh clone where PyYAML is not installed.
+    on a fresh clone without the ``test`` extra, where PyYAML is not installed.
     :class:`TestYAMLAgreesWithTheScanner` is what stops the two from drifting.
 
     """
@@ -2692,7 +2692,7 @@ def test_the_same_job_to_environment_mapping(self) -> None:
         try:
             import yaml
         except ImportError:  # pragma: no cover
-            self.skipTest('PyYAML is not in the test extra; the textual scan is '
+            self.skipTest('PyYAML, from the test extra, is not installed; the textual scan is '
                           'asserted by TestPublishingJobsAreGated')
 
         parsed = yaml.safe_load(self.text)
@@ -2711,7 +2711,7 @@ def test_the_same_job_to_needs_mapping(self) -> None:
         try:
             import yaml
         except ImportError:  # pragma: no cover
-            self.skipTest('PyYAML is not in the test extra; the textual scan is '
+            self.skipTest('PyYAML, from the test extra, is not installed; the textual scan is '
                           'asserted by TestGatedJobsDependOnGithub')
 
         parsed = yaml.safe_load(self.text)
@@ -2738,7 +2738,7 @@ def test_the_same_job_to_if_mapping(self) -> None:
         try:
             import yaml
         except ImportError:  # pragma: no cover
-            self.skipTest('PyYAML is not in the test extra; the textual scan is '
+            self.skipTest('PyYAML, from the test extra, is not installed; the textual scan is '
                           'asserted by TestEvidenceBasedGating')
 
         parsed = yaml.safe_load(self.text)

tests/project/test_unittest_ordering_shards.py

@@ -16,7 +16,7 @@
   ``--exclude``, i.e. runs exactly what it ran before the split.
 
 The workflow is read with a small hand-rolled scan rather than :mod:`yaml`,
-which is in no extra of :file:`pyproject.toml`; the same split
+which comes only with the ``test`` extra of :file:`pyproject.toml`; the same split
 :file:`tests/project/test_workflow_apt_timeouts.py` uses.
 
 """

tests/project/test_workflow_apt_timeouts.py

@@ -39,12 +39,13 @@
   is enforced by the Actions runner, so nothing here can exercise it. The test is
   an assertion over the file, as #641's gating test is.
 
-:mod:`yaml` is in no extra of :file:`pyproject.toml`, so the scanner here is
-hand-rolled and dependency-free, and :class:`TestYAMLAgreesWithTheScanner`
-checks it against :func:`yaml.safe_load` only when PyYAML happens to be
-installed. That is the same split :file:`tests/project/test_release_gates.py`
-uses, and for the same reason: the assertion that must run everywhere does not
-need the dependency, and the one that needs it guards the substitute.
+:mod:`yaml` comes only with the ``test`` extra of :file:`pyproject.toml`, so
+the scanner here is hand-rolled and dependency-free, and
+:class:`TestYAMLAgreesWithTheScanner` checks it against :func:`yaml.safe_load`,
+skipping on an install without that extra. That is the same split
+:file:`tests/project/test_release_gates.py` uses, and for the same reason: the
+assertion that must run everywhere does not need the dependency, and the one
+that needs it guards the substitute.
 
 Comments are stripped before the ``apt-get`` marker is looked for. Without that,
 prose *about* apt -- including the long note #974 added above the very step this
@@ -147,8 +148,8 @@ def steps(path: 'pathlib.Path') -> 'list[Step]':
     """Every step of the workflow at ``path``.
 
     An indentation scan rather than a YAML parse, for the reason this module's
-    docstring gives: PyYAML is in no extra, so the assertion that must run
-    everywhere cannot depend on it.
+    docstring gives: PyYAML comes only with the ``test`` extra, so the
+    assertion that must run everywhere cannot depend on it.
 
     A step runs from its ``- key:`` line to just before the next line that is
     neither blank nor indented past the ``-``, which is what ends a block in
@@ -278,7 +279,7 @@ def setUp(self) -> None:
         try:
             import yaml  # noqa: F401
         except ImportError:  # pragma: no cover
-            self.skipTest('PyYAML is in no extra of pyproject.toml; scanner unchecked here')
+            self.skipTest('PyYAML, from the test extra, is not installed; scanner unchecked here')
 
     def test_yaml_finds_the_same_apt_steps(self) -> None:
         """:func:`yaml.safe_load` agrees on which steps invoke apt."""