Context
Local mutation-testing run against main at 3c1fa01bcf4c26dac79975c18b74c01d577dcf95 (mutmut 3.6.0, committed [tool.mutmut] configuration: source_paths = ["workflow_scripts/"], test selection workflow_scripts/tests/, act-gated workflow tests excluded). Run totals: 1463 mutants — 979 killed, 478 survived, 5 no-tests, 1 timeout.
These scripts power the estate's CI, so mutation gaps here matter most. This issue covers one coherent area; sibling issues cover the rest. Equivalent mutants are recorded in the triage worklist and deliberately omitted here. Inspect any survivor with uv run --with mutmut==3.6.0 mutmut show <name>; names below are workflow_scripts.<module>.x_<function>__mutmut_<n> with the numbers listed per line.
Analysis
mutation_detect_changes.py builds the change-detection matrix for the mutation workflows. The git invocation in changed_files is not integration-tested (dropping --format=, the base ref, or the -- separator survives), the exact matrix JSON contract is unasserted (sort_keys mutants survive), full_run_matrix extra-crate entries and the skip summary are unchecked, and the step-output writer's formatting escapes. 19 survivors are real test gaps; 4 are accepted (below). Mutants marked 2-equivalent in the listing are annotated with their rationale and need no test.
Suggested tests
- An integration test for
changed_files against a temporary git repository (two commits inside and outside the window, a deleted file, and a non-matching pathspec), asserting the exact returned tuple. Killing requires the real git log --since ... --format= <ref> -- <pathspec> semantics, so the argument-dropping mutants die.
- A golden test of
matrix_json asserting the exact serialised string for a two-entry matrix (kills the sort_keys mutants and pins the step-output contract).
full_run_matrix with extra_crate_dirs populated: assert each extra-crate entry is files="", shard=0, shard_count=1 alongside the sharded root entries.scoped_run_matrix with adversarial bucket names (for example a and a-b, plus the root): assert root-first ordering and each entry's dir (kills the dir=None mutant and the item[1] sort-key mutant, which can reorder when a file path and a sibling directory name compare differently)._write_output and _write_skip_summary: assert the exact name=value\n line appended to GITHUB_OUTPUT and the exact rendered skip message (base ref and window hours interpolated) in GITHUB_STEP_SUMMARY._slug_for: assert crates/foo maps to exactly crates-foo.
Accepted survivors (no test to write)
_write_output mutants 2 and 4, and _write_skip_summary mutants 7 and 9 (workflow_scripts/mutation_detect_changes.py:305,314): encoding=None/omitted encoding falls back to the locale encoding and is equivalent on UTF-8 CI runners. Candidate # pragma: no mutate.
Surviving mutants
workflow_scripts/mutation_detect_changes.py:193 in changed_files (mutants 13, 20; 1-test-gap)
- original:
--format=",
- 13:
None,
- 20: ``
workflow_scripts/mutation_detect_changes.py:194 in changed_files (mutants 14, 21; 1-test-gap)
- original:
config.base_ref,
- 14:
None,
- 21: ``
workflow_scripts/mutation_detect_changes.py:195 in changed_files (mutants 15, 22; 1-test-gap)
- original:
--",
- 15:
None,
- 22: ``
workflow_scripts/mutation_detect_changes.py:205 in _is_under (mutants 5, 6, 7; 2-equivalent)
- original:
base_path = PurePosixPath(base.rstrip("/"))
- 5:
base_path = PurePosixPath(base.rstrip(None)) — PurePosixPath ignores trailing '/'; rstrip(None) leaves it, comparison unchanged
- 6:
base_path = PurePosixPath(base.lstrip("/")) — lstrip('/') is a no-op for the relative dirs this receives
- 7:
base_path = PurePosixPath(base.rstrip("XX/XX")) — 'XX/XX' never present; rstrip a no-op, PurePosixPath normalises anyway
workflow_scripts/mutation_detect_changes.py:243 in _slug_for (mutants 9, 10; 1-test-gap)
- original:
return "root" if target_dir == "." else target_dir.replace("/", "-")
- 9:
return "root" if target_dir == "." else target_dir.replace("XX/XX", "-")
- 10:
return "root" if target_dir == "." else target_dir.replace("/", "XX-XX")
workflow_scripts/mutation_detect_changes.py:248 in _relative_files (mutants 2; 2-equivalent)
- original:
if target_dir == ".":
- 2:
if target_dir == "XX.XX": — relative_to(PurePosixPath('.')) returns the path unchanged, same join
workflow_scripts/mutation_detect_changes.py:271 in full_run_matrix (mutants 20, 21, 29, 30; 1-test-gap)
- original:
MatrixEntry(dir=d, slug=_slug_for(d), files="", shard=0, shard_count=1)
- 20:
MatrixEntry(dir=d, slug=_slug_for(d), files=None, shard=0, shard_count=1)
- 21:
MatrixEntry(dir=d, slug=_slug_for(d), files="", shard=None, shard_count=1)
- 29:
MatrixEntry(dir=d, slug=_slug_for(d), files="XXXX", shard=0, shard_count=1)
- 30:
MatrixEntry(dir=d, slug=_slug_for(d), files="", shard=1, shard_count=1)
workflow_scripts/mutation_detect_changes.py:281 in scoped_run_matrix (mutants 3, 5, 7, 9, 10; 1-test-gap/2-equivalent)
- original:
ordered = sorted(buckets.items(), key=lambda item: (item[0] != ".", item[0]))
- 3:
ordered = sorted(buckets.items(), key=None) — '.' sorts before all dir names alphabetically; key=None gives same order
- 5:
ordered = sorted(buckets.items(), ) — default tuple sort preserves root-first order ('.' < letters)
- 7:
ordered = sorted(buckets.items(), key=lambda item: (item[1] != ".", item[0])) — item[1] (list) != '.' always True; falls back to alphabetical, '.' still first
- 9:
ordered = sorted(buckets.items(), key=lambda item: (item[0] != "XX.XX", item[0])) — root sorts first alphabetically regardless of the sentinel
- 10:
ordered = sorted(buckets.items(), key=lambda item: (item[0] != ".", item[1]))
workflow_scripts/mutation_detect_changes.py:285 in scoped_run_matrix (mutants 11; 1-test-gap)
- original:
dir=target_dir,
- 11:
dir=None,
workflow_scripts/mutation_detect_changes.py:299 in matrix_json (mutants 2, 8; 1-test-gap)
- original:
sort_keys=True,
- 2:
sort_keys=None,
- 8:
sort_keys=False,
workflow_scripts/mutation_detect_changes.py:299 in matrix_json (mutants 4; 1-test-gap)
- original:
sort_keys=True, / )
- 4:
)
workflow_scripts/mutation_detect_changes.py:305 in _write_output (mutants 2, 4, 8; 2-equivalent/4-untestable)
- original:
with output_path.open("a", encoding="utf-8") as handle:
- 2:
with output_path.open("a", encoding=None) as handle: — encoding=None locale-dependent
- 4:
with output_path.open("a", ) as handle: — encoding omitted, locale-dependent
- 8:
with output_path.open("a", encoding="UTF-8") as handle: — UTF-8 codec alias
workflow_scripts/mutation_detect_changes.py:314 in _write_skip_summary (mutants 7, 9, 14; 2-equivalent/4-untestable)
- original:
with Path(summary_path).open("a", encoding="utf-8") as handle:
- 7:
with Path(summary_path).open("a", encoding=None) as handle: — encoding=None locale-dependent
- 9:
with Path(summary_path).open("a", ) as handle: — encoding omitted, locale-dependent
- 14:
with Path(summary_path).open("a", encoding="UTF-8") as handle: — UTF-8 codec alias
workflow_scripts/mutation_detect_changes.py:317 in _write_skip_summary (mutants 16, 17; 1-test-gap)
- original:
base_ref=config.base_ref, window_hours=config.window_hours
- 16:
base_ref=None, window_hours=config.window_hours
- 17:
base_ref=config.base_ref, window_hours=None
Context
Local mutation-testing run against
mainat3c1fa01bcf4c26dac79975c18b74c01d577dcf95(mutmut 3.6.0, committed[tool.mutmut]configuration:source_paths = ["workflow_scripts/"], test selectionworkflow_scripts/tests/, act-gated workflow tests excluded). Run totals: 1463 mutants — 979 killed, 478 survived, 5 no-tests, 1 timeout.These scripts power the estate's CI, so mutation gaps here matter most. This issue covers one coherent area; sibling issues cover the rest. Equivalent mutants are recorded in the triage worklist and deliberately omitted here. Inspect any survivor with
uv run --with mutmut==3.6.0 mutmut show <name>; names below areworkflow_scripts.<module>.x_<function>__mutmut_<n>with the numbers listed per line.Analysis
mutation_detect_changes.pybuilds the change-detection matrix for the mutation workflows. The git invocation inchanged_filesis not integration-tested (dropping--format=, the base ref, or the--separator survives), the exactmatrixJSON contract is unasserted (sort_keysmutants survive),full_run_matrixextra-crate entries and the skip summary are unchecked, and the step-output writer's formatting escapes. 19 survivors are real test gaps; 4 are accepted (below). Mutants marked2-equivalentin the listing are annotated with their rationale and need no test.Suggested tests
changed_filesagainst a temporary git repository (two commits inside and outside the window, a deleted file, and a non-matching pathspec), asserting the exact returned tuple. Killing requires the realgit log --since ... --format= <ref> -- <pathspec>semantics, so the argument-dropping mutants die.matrix_jsonasserting the exact serialised string for a two-entry matrix (kills thesort_keysmutants and pins the step-output contract).full_run_matrixwithextra_crate_dirspopulated: assert each extra-crate entry isfiles="",shard=0,shard_count=1alongside the sharded root entries.scoped_run_matrixwith adversarial bucket names (for exampleaanda-b, plus the root): assert root-first ordering and each entry'sdir(kills thedir=Nonemutant and theitem[1]sort-key mutant, which can reorder when a file path and a sibling directory name compare differently)._write_outputand_write_skip_summary: assert the exactname=value\nline appended toGITHUB_OUTPUTand the exact rendered skip message (base ref and window hours interpolated) inGITHUB_STEP_SUMMARY._slug_for: assertcrates/foomaps to exactlycrates-foo.Accepted survivors (no test to write)
_write_outputmutants 2 and 4, and_write_skip_summarymutants 7 and 9 (workflow_scripts/mutation_detect_changes.py:305,314):encoding=None/omitted encoding falls back to the locale encoding and is equivalent on UTF-8 CI runners. Candidate# pragma: no mutate.Surviving mutants
workflow_scripts/mutation_detect_changes.py:193inchanged_files(mutants 13, 20; 1-test-gap)--format=",None,workflow_scripts/mutation_detect_changes.py:194inchanged_files(mutants 14, 21; 1-test-gap)config.base_ref,None,workflow_scripts/mutation_detect_changes.py:195inchanged_files(mutants 15, 22; 1-test-gap)--",None,workflow_scripts/mutation_detect_changes.py:205in_is_under(mutants 5, 6, 7; 2-equivalent)base_path = PurePosixPath(base.rstrip("/"))base_path = PurePosixPath(base.rstrip(None))— PurePosixPath ignores trailing '/'; rstrip(None) leaves it, comparison unchangedbase_path = PurePosixPath(base.lstrip("/"))— lstrip('/') is a no-op for the relative dirs this receivesbase_path = PurePosixPath(base.rstrip("XX/XX"))— 'XX/XX' never present; rstrip a no-op, PurePosixPath normalises anywayworkflow_scripts/mutation_detect_changes.py:243in_slug_for(mutants 9, 10; 1-test-gap)return "root" if target_dir == "." else target_dir.replace("/", "-")return "root" if target_dir == "." else target_dir.replace("XX/XX", "-")return "root" if target_dir == "." else target_dir.replace("/", "XX-XX")workflow_scripts/mutation_detect_changes.py:248in_relative_files(mutants 2; 2-equivalent)if target_dir == ".":if target_dir == "XX.XX":— relative_to(PurePosixPath('.')) returns the path unchanged, same joinworkflow_scripts/mutation_detect_changes.py:271infull_run_matrix(mutants 20, 21, 29, 30; 1-test-gap)MatrixEntry(dir=d, slug=_slug_for(d), files="", shard=0, shard_count=1)MatrixEntry(dir=d, slug=_slug_for(d), files=None, shard=0, shard_count=1)MatrixEntry(dir=d, slug=_slug_for(d), files="", shard=None, shard_count=1)MatrixEntry(dir=d, slug=_slug_for(d), files="XXXX", shard=0, shard_count=1)MatrixEntry(dir=d, slug=_slug_for(d), files="", shard=1, shard_count=1)workflow_scripts/mutation_detect_changes.py:281inscoped_run_matrix(mutants 3, 5, 7, 9, 10; 1-test-gap/2-equivalent)ordered = sorted(buckets.items(), key=lambda item: (item[0] != ".", item[0]))ordered = sorted(buckets.items(), key=None)— '.' sorts before all dir names alphabetically; key=None gives same orderordered = sorted(buckets.items(), )— default tuple sort preserves root-first order ('.' < letters)ordered = sorted(buckets.items(), key=lambda item: (item[1] != ".", item[0]))— item[1] (list) != '.' always True; falls back to alphabetical, '.' still firstordered = sorted(buckets.items(), key=lambda item: (item[0] != "XX.XX", item[0]))— root sorts first alphabetically regardless of the sentinelordered = sorted(buckets.items(), key=lambda item: (item[0] != ".", item[1]))workflow_scripts/mutation_detect_changes.py:285inscoped_run_matrix(mutants 11; 1-test-gap)dir=target_dir,dir=None,workflow_scripts/mutation_detect_changes.py:299inmatrix_json(mutants 2, 8; 1-test-gap)sort_keys=True,sort_keys=None,sort_keys=False,workflow_scripts/mutation_detect_changes.py:299inmatrix_json(mutants 4; 1-test-gap)sort_keys=True, / ))workflow_scripts/mutation_detect_changes.py:305in_write_output(mutants 2, 4, 8; 2-equivalent/4-untestable)with output_path.open("a", encoding="utf-8") as handle:with output_path.open("a", encoding=None) as handle:— encoding=None locale-dependentwith output_path.open("a", ) as handle:— encoding omitted, locale-dependentwith output_path.open("a", encoding="UTF-8") as handle:— UTF-8 codec aliasworkflow_scripts/mutation_detect_changes.py:314in_write_skip_summary(mutants 7, 9, 14; 2-equivalent/4-untestable)with Path(summary_path).open("a", encoding="utf-8") as handle:with Path(summary_path).open("a", encoding=None) as handle:— encoding=None locale-dependentwith Path(summary_path).open("a", ) as handle:— encoding omitted, locale-dependentwith Path(summary_path).open("a", encoding="UTF-8") as handle:— UTF-8 codec aliasworkflow_scripts/mutation_detect_changes.py:317in_write_skip_summary(mutants 16, 17; 1-test-gap)base_ref=config.base_ref, window_hours=config.window_hoursbase_ref=None, window_hours=config.window_hoursbase_ref=config.base_ref, window_hours=None