Count multi-line statement sites as covered from their start line; skip TypeScript type positions

tests/test_boundaries.py

@@ -921,3 +921,12 @@ def test_snapshots_keep_other_files_empty_directories_and_odd_records(tmp_path):
     assert not (base / "empty").exists()
     assert (full / "keep.edn").is_file()
     _remove_empty_dirs(tmp_path / "missing-metrics")
+
+
+def test_scan_counts_a_site_inside_a_covered_multi_line_statement(tmp_path):
+    path = tmp_path / "src" / "demo.py"
+    path.parent.mkdir()
+    path.write_text("def add(a, b):\n    return (a\n            + b)\n", encoding="utf-8")
+    scanned = scan_file(path, tmp_path, covered_lines={2}, ignore_coverage=False, lines=None)
+    assert "uncovered" not in scanned
+    assert "+ -> -" in scanned

tests/test_engine.py

@@ -113,6 +113,29 @@ def test_uncovered_sites_are_not_executed(tmp_path):
     assert result.forms[0].sites == 4
 
 
+def test_a_site_inside_a_covered_multi_line_statement_is_run(tmp_path):
+    # LCOV marks only the line a statement starts on.
+    path = tmp_path / "src" / "demo.py"
+    path.parent.mkdir()
+    path.write_text("def add(a, b):\n    return (a\n            + b)\n", encoding="utf-8")
+    runner = FakeRunner()
+    result = mutate_file(
+        path,
+        tmp_path,
+        runner=runner,
+        covered_lines={2},
+        ignore_coverage=False,
+        mutate_all=True,
+        lines=None,
+        test_command="fake",
+        timeout_factor=10,
+        mutation_warning=50,
+        baselines={},
+    )
+    assert result.forms[0].uncovered == 0
+    assert result.forms[0].killed == 1
+
+
 def test_a_failed_baseline_does_not_rewrite_metrics(tmp_path):
     path = tmp_path / "src" / "demo.py"
     path.parent.mkdir()

tests/test_sites.py

@@ -203,3 +203,34 @@ def test_a_deep_expression_is_walked(tmp_path):
     assert discover_raw(python, "python", "app.py")
     go = f"package p\nfunc place() int {{ return {expr} }}\n"
     assert discover_raw(go, "go", "app.go")
+
+
+def test_typescript_types_are_not_mutation_sites(tmp_path):
+    source = """type Flag = { on: true };
+interface Box { open: false }
+export function check(n: number): { ok: true } | { ok: false; used?: true } {
+  const seen: Promise<{ done: false }> | null = null;
+  return { ok: n > 0 };
+}
+"""
+    sites = _sites(tmp_path, "src/demo/check.ts", source)
+    described = {(site.line, site.original, site.mutant) for site in sites}
+    assert described == {(5, ">", ">="), (5, "0", "1")}
+
+
+def test_a_site_remembers_where_its_statement_starts(tmp_path):
+    source = """export function save(db: Db, now: number) {
+  db
+    .prepare("x")
+    .bind(now + 1)
+    .run();
+  return {
+    ok: true,
+  };
+}
+"""
+    sites = _sites(tmp_path, "src/demo/save.ts", source)
+    anchors = {(site.line, site.original, site.anchor_line) for site in sites}
+    assert (4, "+", 2) in anchors
+    assert (4, "1", 2) in anchors
+    assert (7, "true", 6) in anchors