Add rustdoc GUI regression test for #151209

Author: GuillaumeGomez

tests/rustdoc-gui/mobile-topbar-menu-popovers.goml

@@ -0,0 +1,33 @@
+// Ensure that topbar popover menus content can be scrolled on mobile.
+go-to: "file://" + |DOC_PATH| + "/lib2/index.html"
+store-value: (window_height, 500)
+set-window-size: (400, |window_height|)
+
+include: "utils.goml"
+
+// We open the settings menu
+call-function: ("open-settings-menu", {})
+// We ensure it's not scrolled down yet.
+assert-property: ("#settings", {"scrollTop": 0})
+// We ensure its height is smaller than the window's, but its content's height is bigger.
+store-property: ("#settings", {"offsetHeight": menu_height, "scrollHeight": scroll_height})
+assert: |menu_height| < |window_height| && |scroll_height| > |window_height|
+
+// We scroll to the last element of the menu.
+scroll-to: "#settings .setting-line:last-of-type input"
+// The item should be visible now, and so the Y scroll value should have changed.
+assert-property: ("#settings", {"scrollTop": 295})
+
+// Now we open the help menu.
+click: ".help-menu a"
+wait-for: "#help"
+// We ensure it's not scrolled down yet.
+assert-property: ("#help", {"scrollTop": 0})
+// We ensure its height is smaller than the window's, but its content's height is bigger.
+store-property: ("#help", {"offsetHeight": menu_height, "scrollHeight": scroll_height})
+assert: |menu_height| < |window_height| && |scroll_height| > |window_height|
+
+// We scroll to the last element of the menu.
+scroll-to: "#help .infos > :last-child"
+// The item should be visible now, and so the Y scroll value should have changed.
+assert-property: ("#help", {"scrollTop": 339})