Rename tests.scan.test_basic.test_pushout_dot and add a test description

tests/scan/test_basic.py

@@ -3014,18 +3014,29 @@ class TestScan:
         utt.assert_allclose(vnh0, tnh0, atol=1e-6)
         utt.assert_allclose(vnW, tnW, atol=1e-6)
 
-    def test_pushout_dot(self):
+    def test_inner_replace_dot(self):
+        """
+        This tests that rewrites are applied to the inner-graph.
+        In particular, BLAS-based rewrites that remove the original dot product.
+
+        This was previously a test with a name that implied it was testing the
+        `Scan` push-out rewrites, but it wasn't testing that at all, because the
+        rewrites were never being applied.
+        """
         W = matrix("W")
         h = matrix("h")
 
+        mode = mode_with_opt  # .excluding("BlasOpt")
+
         o, _ = scan(
             lambda hi, him1, W: (hi, dot(hi + him1, W)),
             outputs_info=[at.zeros([h.shape[1]]), None],
             sequences=[h],
             non_sequences=[W],
+            mode=mode,
         )
 
-        f = function([W, h], o, mode=mode_with_opt)
+        f = function([W, h], o, mode=mode)
 
         scan_nodes = [x for x in f.maker.fgraph.toposort() if isinstance(x.op, Scan)]
         assert len(scan_nodes) == 1