--- a/testing/web-platform/meta/webdriver/tests/set_window_rect.py.ini
+++ b/testing/web-platform/meta/webdriver/tests/set_window_rect.py.ini
@@ -1,7 +1,13 @@
 [set_window_rect.py]
   type: wdspec
   [set_window_rect.py::test_handle_prompt_accept]
     expected: FAIL
 
   [set_window_rect.py::test_handle_prompt_missing_value]
     expected: FAIL
+
+  [set_window_rect.py::test_width_height_floats]
+    expected: FAIL
+
+  [set_window_rect.py::test_x_y_floats]
+    expected: FAIL

--- a/testing/web-platform/tests/webdriver/tests/set_window_rect.py
+++ b/testing/web-platform/tests/webdriver/tests/set_window_rect.py
@@ -192,32 +192,68 @@ def test_out_of_bounds(session, rect):
 
     9. If x or y is neither null nor a Number from -(263) to 263 - 1,
     return error with error code invalid argument.
     """
     response = set_window_rect(session, rect)
     assert_error(response, "invalid argument")
 
 
+def test_width_height_floats(session):
+    """
+    8. If width or height is neither null nor a Number from 0 to 2^64 -
+    1, return error with error code invalid argument.
+    """
+
+    response = set_window_rect(session, {"width": 200.5, "height": 400})
+    value = assert_success(response)
+    assert value["width"] == 200.2
+    assert value["height"] == 400
+
+    response = set_window_rect(session, {"width": 300, "height": 450.5})
+    value = assert_success(response)
+    assert value["width"] == 300
+    assert value["height"] == 450.5
+
+
+def test_x_y_floats(session):
+    """
+    9. If x or y is neither null nor a Number from -(263) to 263 - 1,
+    return error with error code invalid argument.
+    """
+
+    response = set_window_rect(session, {"x": 200.5, "y": 400})
+    value = assert_success(response)
+    assert value["x"] == 200.2
+    assert value["y"] == 400
+
+    response = set_window_rect(session, {"x": 300, "y": 450.5})
+    value = assert_success(response)
+    assert value["x"] == 300
+    assert value["y"] == 450.5
+
+
+    original = session.window.rect
+
+
 def test_fully_exit_fullscreen(session):
     """
     10. Fully exit fullscreen.
 
     [...]
 
     To fully exit fullscreen a document document, run these steps:
 
       1. If document's fullscreen element is null, terminate these steps.
 
       2. Unfullscreen elements whose fullscreen flag is set, within
       document's top layer, except for document's fullscreen element.
 
       3. Exit fullscreen document.
     """
-
     session.window.fullscreen()
     assert session.execute_script("return window.fullScreen") is True
 
     response = set_window_rect(session, {"width": 400, "height": 400})
     value = assert_success(response)
     assert value["width"] == 400
     assert value["height"] == 400
     assert value["state"] == "normal"