script: Implement fully exit fullscreen steps partially - #47123

diff --git a/components/servo/tests/common/mod.rs b/components/servo/tests/common/mod.rs
index dbce0574f59..4305cb50696 100644
--- a/components/servo/tests/common/mod.rs
+++ b/components/servo/tests/common/mod.rs
@@ -97,6 +97,7 @@ pub(crate) struct WebViewDelegateImpl {
     pub(crate) number_of_controls_hidden: Cell<usize>,
     pub(crate) last_accesskit_tree_updates: RefCell<Vec<accesskit::TreeUpdate>>,
     pub(crate) console_messages: RefCell<Vec<(ConsoleLogLevel, String)>>,
+    pub(crate) fullscreen: Cell<bool>,
 }
 
 #[allow(dead_code)] // Used by some tests and not others
@@ -165,6 +166,10 @@ impl WebViewDelegate for WebViewDelegateImpl {
     fn show_console_message(&self, _webview: WebView, level: ConsoleLogLevel, message: String) {
         self.console_messages.borrow_mut().push((level, message));
     }
+
+    fn notify_fullscreen_state_changed(&self, _webview: WebView, is_fullscreen: bool) {
+        self.fullscreen.set(is_fullscreen);
+    }
 }
 
 // Used by some unit tests only. Since they compile into different binaries,
diff --git a/components/servo/tests/webview.rs b/components/servo/tests/webview.rs
index 6d8f74ebf60..a8b3d9f1ebe 100644
--- a/components/servo/tests/webview.rs
+++ b/components/servo/tests/webview.rs
@@ -1134,3 +1134,39 @@ fn test_preferences_change() {
         )
     );
 }
+
+#[test]
+fn test_fullscreen() {
+    let servo_test = ServoTest::new();
+    let delegate = Rc::new(WebViewDelegateImpl::default());
+
+    let test_page = Url::parse(
+        "data:text/html,\
+        <button onclick='this.requestFullscreen()'>click</button>\
+        <a href=about:blank>click</a>",
+    )
+    .expect("Data URL failed to build");
+
+    let webview = WebViewBuilder::new(servo_test.servo(), servo_test.rendering_context.clone())
+        .delegate(delegate.clone())
+        .url(test_page.clone())
+        .build();
+    show_webview_and_wait_for_rendering_to_be_ready(&servo_test, &webview, &delegate);
+
+    click_at_point(&webview, Point2D::new(10., 10.));
+
+    let captured = delegate.clone();
+    servo_test.spin(move || !captured.fullscreen.get());
+
+    assert!(
+        evaluate_javascript(
+            &servo_test,
+            webview.clone(),
+            "document.querySelector('a').click();"
+        )
+        .is_ok()
+    );
+
+    let captured = delegate.clone();
+    servo_test.spin(move || captured.fullscreen.get());
+}