diff --git a/tests/test_sdl_parity.py b/tests/test_sdl_parity.py
new file mode 100644
index 0000000..77f8ccd
--- /dev/null
+++ b/tests/test_sdl_parity.py
@@ -0,0 +1,23 @@
+"""Run the SDL parity gate as a real test.
+
+``tools/schema_parity.py`` asserts the Strawberry schema is byte-identical (order-insensitive)
+to the frozen ``schema.legacy.graphql`` baseline. It was a standalone script; running it here
+makes it a permanent CI gate (and covers the tool).
+"""
+
+from solvis_graphql_api.tools import schema_parity
+
+
+def test_sdl_parity_matches_legacy_baseline():
+    # the migrated Strawberry SDL must still equal the frozen graphene baseline
+    assert schema_parity.diff() == ""
+    assert schema_parity.main() == 0
+
+
+def test_sdl_parity_reports_drift(tmp_path, monkeypatch):
+    # point the baseline at a different (valid) SDL → the gate must flag the drift
+    bad_baseline = tmp_path / "baseline.graphql"
+    bad_baseline.write_text("type Query { somethingCompletelyDifferent: String }")
+    monkeypatch.setattr(schema_parity, "BASELINE", bad_baseline)
+    assert schema_parity.diff()  # non-empty unified diff
+    assert schema_parity.main() == 1