fix(mge/functional): fix F.ones when input is a tensor of scalar type

GitOrigin-RevId: 6d01d6b58d0445b42cc3f3e5f137ebd590af31a4

imperative/python/megengine/functional/tensor.py

@@ -108,7 +108,7 @@ def full(shape, value, dtype="float32", device=None):
     if device is None:
         device = get_default_device()
     (x,) = Const(value, dtype=dtype, device=device)()
-    if len(shape) == 0:  # scalar
+    if shape is ():  # scalar.shape
         return x
     return broadcast_to(x, shape)
 

imperative/python/test/unit/functional/test_functional.py

@@ -739,3 +739,10 @@ def test_cvt_color():
     x = tensor(inp)
     y = F.img_proc.cvt_color(x, mode="RGB2GRAY")
     np.testing.assert_allclose(y.numpy(), out, atol=1e-5)
+
+
+@pytest.mark.parametrize("val", [2, [2,], [2, 3]])
+def test_ones(val):
+    shp = tensor(val)
+    np_shp = np.array(val)
+    np.testing.assert_equal(F.ones(shp), np.ones(np_shp))