Add test for 'verify_grad' without explicit RNG

Author: Mohit Kumar

pytensor/gradient.py

@@ -1770,14 +1770,9 @@ def verify_grad(
     if rel_tol is None:
         rel_tol = max(_type_tol[str(p.dtype)] for p in pt)
 
+    # Initialize RNG if not provided
     if rng is None:
-        raise TypeError(
-            "rng should be a valid instance of "
-            "numpy.random.RandomState. You may "
-            "want to use tests.unittest"
-            "_tools.verify_grad instead of "
-            "pytensor.gradient.verify_grad."
-        )
+        rng = np.random.default_rng()
 
     # We allow input downcast in `function`, because `numeric_grad` works in
     # the most precise dtype used among the inputs, so we may need to cast

tests/test_gradient.py

@@ -3,6 +3,7 @@
 from scipy.optimize import rosen_hess_prod
 
 import pytensor
+import pytensor.tensor as pt
 import pytensor.tensor.basic as ptb
 from pytensor.configdefaults import config
 from pytensor.gradient import (
@@ -602,6 +603,10 @@ def test_grad_constant(self):
                 + str(g_one)
             )
 
+    def test_verify_grad_no_rng(self):
+        """Test `verify_grad` works without requiring an explicit RNG."""
+        utt.verify_grad(pt.log, [2.0])
+
 
 def test_known_grads():
     # Tests that the grad method with no known_grads