test: enforce Wave A quality lock

tests/test_coverage_thresholds.py

@@ -165,3 +165,142 @@ def test_changed_line_gate_accepts_exact_floor():
     assert MODULE.validate_changed_coverage(
         _report(), changed, minimum=75.0,
     ) == []
+
+
+def _module_report(
+    path: str = "obliteratus/example.py",
+    *,
+    covered_lines: int = 8,
+    statements: int = 10,
+    covered_branches: int = 3,
+    branches: int = 4,
+) -> dict[str, object]:
+    return {
+        "files": {
+            path: {
+                "summary": {
+                    "covered_lines": covered_lines,
+                    "num_statements": statements,
+                    "covered_branches": covered_branches,
+                    "num_branches": branches,
+                },
+            },
+        },
+    }
+
+
+def test_parse_changed_modules_handles_nul_renames_and_filters_nonproduction():
+    raw = (
+        b"M\0obliteratus/current.py\0"
+        b"A\0tests/test_current.py\0"
+        b"D\0obliteratus/deleted.py\0"
+        b"R100\0obliteratus/old.py\0obliteratus/new.py\0"
+        b"R100\0obliteratus/removed.py\0docs/removed.py\0"
+        b"C100\0obliteratus/source.py\0obliteratus/copied.py\0"
+    )
+
+    assert MODULE.parse_changed_modules(raw) == [
+        MODULE.ChangedModule("M", "obliteratus/current.py", "obliteratus/current.py"),
+        MODULE.ChangedModule("D", "obliteratus/deleted.py", "obliteratus/deleted.py"),
+        MODULE.ChangedModule("R100", "obliteratus/old.py", "obliteratus/new.py"),
+        MODULE.ChangedModule("D", "obliteratus/removed.py", "obliteratus/removed.py"),
+        MODULE.ChangedModule("C100", None, "obliteratus/copied.py"),
+    ]
+
+
+def test_parse_changed_modules_rejects_truncated_and_unknown_statuses():
+    import pytest
+
+    with pytest.raises(ValueError, match="truncated"):
+        MODULE.parse_changed_modules(b"R100\0obliteratus/old.py\0")
+    with pytest.raises(ValueError, match="unsupported"):
+        MODULE.parse_changed_modules(b"U\0obliteratus/example.py\0")
+
+
+def test_touched_module_gate_reports_line_and_branch_regressions_separately():
+    base = _module_report(covered_lines=9, covered_branches=4)
+    head = _module_report(covered_lines=8, covered_branches=3)
+    changes = [MODULE.ChangedModule("M", "obliteratus/example.py", "obliteratus/example.py")]
+
+    assert MODULE.validate_touched_module_regression(head, base, changes) == [
+        "touched module obliteratus/example.py line coverage regressed from 90.00% to 80.00%",
+        "touched module obliteratus/example.py branch coverage regressed from 100.00% to 75.00%",
+    ]
+
+
+def test_touched_module_gate_applies_tolerances_to_existing_module():
+    base = _module_report(covered_lines=801, statements=1000, covered_branches=751, branches=1000)
+    head = _module_report(covered_lines=800, statements=1000, covered_branches=750, branches=1000)
+    changes = [MODULE.ChangedModule("M", "obliteratus/example.py", "obliteratus/example.py")]
+
+    assert MODULE.validate_touched_module_regression(
+        head,
+        base,
+        changes,
+        line_tolerance=0.1,
+        branch_tolerance=0.1,
+    ) == []
+    assert len(MODULE.validate_touched_module_regression(
+        head,
+        base,
+        changes,
+        line_tolerance=0.09,
+        branch_tolerance=0.09,
+    )) == 2
+
+
+def test_touched_module_gate_enforces_new_module_floors():
+    head = _module_report(covered_lines=7, statements=10, covered_branches=2, branches=4)
+    changes = [MODULE.ChangedModule("A", None, "obliteratus/example.py")]
+
+    assert MODULE.validate_touched_module_regression(head, {}, changes) == [
+        "new module obliteratus/example.py line coverage 70.00% is below the 80.00% floor",
+        "new module obliteratus/example.py branch coverage 50.00% is below the 75.00% floor",
+    ]
+
+
+def test_touched_module_gate_requires_floor_when_existing_module_adds_branches():
+    base = _module_report(covered_branches=0, branches=0)
+    head = _module_report(covered_branches=2, branches=4)
+    changes = [MODULE.ChangedModule("M", "obliteratus/example.py", "obliteratus/example.py")]
+
+    assert MODULE.validate_touched_module_regression(head, base, changes) == [
+        "touched module obliteratus/example.py added branches at 50.00% coverage, "
+        "below the 75.00% floor",
+    ]
+
+
+def test_touched_module_gate_accepts_branch_removal_and_rename():
+    base = _module_report("obliteratus/old.py", covered_branches=3, branches=4)
+    head = _module_report("obliteratus/new.py", covered_branches=0, branches=0)
+    changes = [MODULE.ChangedModule("R100", "obliteratus/old.py", "obliteratus/new.py")]
+
+    assert MODULE.validate_touched_module_regression(head, base, changes) == []
+
+
+def test_touched_module_gate_rejects_missing_and_malformed_measurements():
+    changes = [MODULE.ChangedModule("M", "obliteratus/example.py", "obliteratus/example.py")]
+    assert MODULE.validate_touched_module_regression({}, _module_report(), changes) == [
+        "coverage report is missing touched module obliteratus/example.py",
+    ]
+
+    malformed = _module_report()
+    malformed["files"]["obliteratus/example.py"]["summary"]["covered_lines"] = True
+    assert MODULE.validate_touched_module_regression(malformed, _module_report(), changes) == [
+        "coverage report has invalid covered_lines for touched module obliteratus/example.py",
+    ]
+
+
+def test_touched_module_gate_rejects_missing_base_measurement():
+    changes = [MODULE.ChangedModule("M", "obliteratus/example.py", "obliteratus/example.py")]
+    assert MODULE.validate_touched_module_regression(_module_report(), {}, changes) == [
+        "base coverage report is missing touched module obliteratus/example.py",
+    ]
+
+
+def test_touched_module_gate_requires_reviewed_exception_for_deletion():
+    changes = [MODULE.ChangedModule("D", "obliteratus/example.py", "obliteratus/example.py")]
+    assert MODULE.validate_touched_module_regression({}, _module_report(), changes) == [
+        "deleted production module obliteratus/example.py requires an explicit reviewed "
+        "coverage-policy exception",
+    ]