diff --git a/chainladder/development/tests/test_development.py b/chainladder/development/tests/test_development.py
index 54086cce..ce33b892 100644
--- a/chainladder/development/tests/test_development.py
+++ b/chainladder/development/tests/test_development.py
@@ -40,7 +40,7 @@ def test_drop2(raa):
 def test_n_periods():
     d = cl.load_sample("usauto")["incurred"]
     xp = np if d.array_backend == "sparse" else d.get_array_module()
-    return xp.all(
+    assert xp.all(
         xp.around(
             xp.unique(
                 cl.Development(n_periods=3, average="volume").fit(d).ldf_.values,