Fix antigravity (#1017)

* Fix antigravity

* Add test

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

pyscriptjs/tests/integration/test_zz_examples.py

@@ -98,6 +98,29 @@ class TestExamples(PyScriptTest):
         assert see_source_link.is_visible()
         self.assert_no_banners()
 
+    def test_antigravity(self):
+        self.goto("examples/antigravity.html")
+        self.wait_for_pyscript()
+        assert self.page.title() == "Antigravity"
+
+        # confirm that svg added to page
+        wait_for_render(self.page, "*", '<svg.*id="svg8".*>')
+
+        # Get svg layer of flying character
+        char = self.page.wait_for_selector("#python")
+        assert char is not None
+
+        # check that character moves in negative-y direction over time
+        ycoord_pattern = r"translate\(-?\d*\.\d*,\s(?P<ycoord>-?[\d.]+)\)"
+        starting_y_coord = float(
+            re.match(ycoord_pattern, char.get_attribute("transform")).group("ycoord")
+        )
+        time.sleep(2)
+        later_y_coord = float(
+            re.match(ycoord_pattern, char.get_attribute("transform")).group("ycoord")
+        )
+        assert later_y_coord < starting_y_coord
+
     def test_bokeh(self):
         # XXX improve this test
         self.goto("examples/bokeh.html")