Add split test

tests/link/pytorch/test_basic.py

@@ -12,7 +12,7 @@
 from pytensor.compile.sharedvalue import SharedVariable, shared
 from pytensor.configdefaults import config
 from pytensor.graph import RewriteDatabaseQuery
-from pytensor.graph.basic import Apply
+from pytensor.graph.basic import Apply, Constant
 from pytensor.graph.fg import FunctionGraph
 from pytensor.graph.op import Op
 from pytensor.ifelse import ifelse
@@ -38,6 +38,11 @@
 py_mode = Mode(linker="py", optimizer=None)
 
 
+def set_test_value(x, v):
+    x.tag.test_value = v
+    return x
+
+
 def compare_pytorch_and_py(
     fgraph: FunctionGraph,
     test_inputs: Iterable,
@@ -471,3 +476,66 @@ def test_ScalarLoop_Elemwise_multi_carries():
     compare_pytorch_and_py(
         f, args, assert_fn=partial(np.testing.assert_allclose, rtol=1e-6)
     )
+
+
+rng = np.random.default_rng(42849)
+
+
+@pytest.mark.parametrize(
+    "n_splits, axis, values, sizes",
+    [
+        (
+            0,
+            0,
+            set_test_value(pt.vector(), rng.normal(size=20).astype(config.floatX)),
+            set_test_value(pt.vector(dtype="int64"), []),
+        ),
+        (
+            5,
+            0,
+            set_test_value(pt.vector(), rng.normal(size=5).astype(config.floatX)),
+            set_test_value(
+                pt.vector(dtype="int64"), rng.multinomial(5, np.ones(5) / 5)
+            ),
+        ),
+        (
+            5,
+            0,
+            set_test_value(pt.vector(), rng.normal(size=10).astype(config.floatX)),
+            set_test_value(
+                pt.vector(dtype="int64"), rng.multinomial(10, np.ones(5) / 5)
+            ),
+        ),
+        (
+            5,
+            -1,
+            set_test_value(pt.matrix(), rng.normal(size=(11, 7)).astype(config.floatX)),
+            set_test_value(
+                pt.vector(dtype="int64"), rng.multinomial(7, np.ones(5) / 5)
+            ),
+        ),
+        (
+            5,
+            -2,
+            set_test_value(pt.matrix(), rng.normal(size=(11, 7)).astype(config.floatX)),
+            set_test_value(
+                pt.vector(dtype="int64"), rng.multinomial(11, np.ones(5) / 5)
+            ),
+        ),
+    ],
+)
+def test_Split(n_splits, axis, values, sizes):
+    g = pt.split(values, sizes, n_splits, axis=axis)
+    assert len(g) == n_splits
+    if n_splits == 0:
+        return
+    g_fg = FunctionGraph(outputs=[g] if n_splits == 1 else g)
+
+    compare_pytorch_and_py(
+        g_fg,
+        [
+            i.tag.test_value
+            for i in g_fg.inputs
+            if not isinstance(i, SharedVariable | Constant)
+        ],
+    )