Add GUI regression test for position of warning block

Author: GuillaumeGomez

Diff for: tests/rustdoc-gui/src/test_docs/lib.rs

@@ -85,6 +85,9 @@ impl AsRef<str> for Foo {
     }
 }
 
+/// <div id="doc-warning-0" class="warning">I have warnings!</div>
+pub struct WarningStruct;
+
 /// Just a normal enum.
 ///
 /// # title!

Diff for: tests/rustdoc-gui/warning-block.goml

@@ -2,6 +2,7 @@
 go-to: "file://" + |DOC_PATH| + "/test_docs/struct.Foo.html"
 show-text: true
 
+store-value: (default_y_pos, 5)
 define-function: (
     "check-warning",
     (theme, color, border_color),
@@ -16,12 +17,18 @@ define-function: (
             "border-left": "2px solid " + |border_color|,
             "background-color": "transparent",
         })
+        store-position: ("#doc-warning-1", {"y": warn_div_y})
+        store-position: ("#doc-warning-1::before", {"y": warn_y})
+        assert: |warn_y| == |warn_div_y| + |default_y_pos|
         assert-css: ("#doc-warning-2", {
             "margin-bottom": "0px",
             "color": |color|,
             "border-left": "2px solid " + |border_color|,
             "background-color": "transparent",
         })
+        store-position: ("#doc-warning-2", {"y": warn_div_y})
+        store-position: ("#doc-warning-2::before", {"y": warn_y})
+        assert: |warn_y| == |warn_div_y| + |default_y_pos|
     },
 )
 
@@ -40,3 +47,9 @@ call-function: ("check-warning", {
     "color": "black",
     "border_color": "#ff8e00",
 })
+
+// We ensure that the warning element in the top doc is not overlaying the "[-]" button.
+go-to: "file://" + |DOC_PATH| + "/test_docs/struct.WarningStruct.html"
+store-position: ("#doc-warning-0", {"y": warn_div_y})
+store-position: ("#doc-warning-0::before", {"y": warn_y})
+assert: |warn_y| == |warn_div_y| + |default_y_pos| + 15