[py][bidi] Allow resetting viewport

py/selenium/webdriver/common/bidi/browsing_context.py

@@ -20,9 +20,13 @@
 from dataclasses import dataclass
 from typing import Any
 
+from typing_extensions import Sentinel
+
 from selenium.webdriver.common.bidi.common import command_builder
 from selenium.webdriver.common.bidi.session import Session
 
+UNDEFINED = Sentinel("UNDEFINED")
+
 
 class ReadinessState:
     """Represents the stage of document loading at which a navigation command will return."""
@@ -980,16 +984,16 @@ def reload(
     def set_viewport(
         self,
         context: str | None = None,
-        viewport: dict | None = None,
-        device_pixel_ratio: float | None = None,
+        viewport: dict | None | UNDEFINED = UNDEFINED,
+        device_pixel_ratio: float | None | UNDEFINED = UNDEFINED,
         user_contexts: list[str] | None = None,
     ) -> None:
         """Modifies specific viewport characteristics on the given top-level traversable.
 
         Args:
             context: The browsing context ID.
-            viewport: The viewport parameters.
-            device_pixel_ratio: The device pixel ratio.
+            viewport: The viewport parameters (`None` resets to default).
+            device_pixel_ratio: The device pixel ratio (`None` resets default).
             user_contexts: The user context IDs.
 
         Raises:
@@ -998,9 +1002,17 @@ def set_viewport(
         params: dict[str, Any] = {}
         if context is not None:
             params["context"] = context
-        if viewport is not None:
+        if viewport is UNDEFINED:
+            pass
+        elif viewport is None:
+            params["viewport"] = None
+        else:
             params["viewport"] = viewport
-        if device_pixel_ratio is not None:
+        if device_pixel_ratio is UNDEFINED:
+            pass
+        elif device_pixel_ratio is None:
+            params["devicePixelRatio"] = None
+        else:
             params["devicePixelRatio"] = device_pixel_ratio
         if user_contexts is not None:
             params["userContexts"] = user_contexts

py/test/selenium/webdriver/common/bidi_browsing_context_tests.py

@@ -348,31 +348,62 @@ def test_set_viewport(driver, pages):
     context_id = driver.current_window_handle
     driver.get(pages.url("formPage.html"))
 
-    driver.browsing_context.set_viewport(context=context_id, viewport={"width": 250, "height": 300})
+    try:
+        driver.browsing_context.set_viewport(context=context_id, viewport={"width": 251, "height": 301})
 
-    viewport_size = driver.execute_script("return [window.innerWidth, window.innerHeight];")
+        viewport_size = driver.execute_script("return [window.innerWidth, window.innerHeight];")
 
-    assert viewport_size[0] == 250
-    assert viewport_size[1] == 300
+        assert viewport_size[0] == 251
+        assert viewport_size[1] == 301
+    finally:
+        driver.browsing_context.set_viewport(context=context_id, viewport=None, device_pixel_ratio=None)
 
 
 def test_set_viewport_with_device_pixel_ratio(driver, pages):
     """Test setting the viewport with device pixel ratio."""
     context_id = driver.current_window_handle
     driver.get(pages.url("formPage.html"))
 
-    driver.browsing_context.set_viewport(
-        context=context_id, viewport={"width": 250, "height": 300}, device_pixel_ratio=5
-    )
+    try:
+        driver.browsing_context.set_viewport(
+            context=context_id, viewport={"width": 252, "height": 302}, device_pixel_ratio=5
+        )
+
+        viewport_size = driver.execute_script("return [window.innerWidth, window.innerHeight];")
+
+        assert viewport_size[0] == 252
+        assert viewport_size[1] == 302
+
+        device_pixel_ratio = driver.execute_script("return window.devicePixelRatio")
+
+        assert device_pixel_ratio == 5
+    finally:
+        driver.browsing_context.set_viewport(context=context_id, viewport=None, device_pixel_ratio=None)
 
-    viewport_size = driver.execute_script("return [window.innerWidth, window.innerHeight];")
 
-    assert viewport_size[0] == 250
-    assert viewport_size[1] == 300
+def test_set_viewport_back_to_default(driver, pages):
+    """Test resetting the viewport and device pixel ratio to defaults."""
+    context_id = driver.current_window_handle
+    driver.get(pages.url("formPage.html"))
+
+    default_viewport_size = driver.execute_script("return [window.innerWidth, window.innerHeight];")
+    default_device_pixel_ratio = driver.execute_script("return window.devicePixelRatio")
+
+    try:
+        driver.browsing_context.set_viewport(
+            context=context_id, viewport={"width": 253, "height": 303}, device_pixel_ratio=10
+        )
+
+        driver.browsing_context.set_viewport(context=context_id, viewport=None, device_pixel_ratio=None)
 
-    device_pixel_ratio = driver.execute_script("return window.devicePixelRatio")
+        viewport_size = driver.execute_script("return [window.innerWidth, window.innerHeight];")
+        device_pixel_ratio = driver.execute_script("return window.devicePixelRatio")
 
-    assert device_pixel_ratio == 5
+        assert viewport_size[0] == default_viewport_size[0]
+        assert viewport_size[1] == default_viewport_size[1]
+        assert device_pixel_ratio == default_device_pixel_ratio
+    finally:
+        driver.browsing_context.set_viewport(context=context_id, viewport=None, device_pixel_ratio=None)
 
 
 def test_print_page(driver, pages):