Add GUI test for "no result found" links

Author: GuillaumeGomez

src/test/rustdoc-gui/search-no-result.goml

@@ -0,0 +1,36 @@
+// The goal of this test is to check the color of the "no result" links.
+goto: "file://" + |DOC_PATH| + "/lib2/index.html?search=sdkfskjfsdks"
+show-text: true
+
+define-function: (
+    "check-no-result",
+    (theme, link, link_hover),
+    [
+        // Changing theme.
+        ("local-storage", {"rustdoc-theme": |theme|, "rustdoc-use-system-theme": "false"}),
+        ("reload"),
+        ("wait-for", "#results"),
+        ("assert", ".search-failed.active"),
+        ("assert-css", ("#results a", {"color": |link|}, ALL)),
+        ("move-cursor-to", "#results a"),
+        ("assert-css", ("#results a:hover", {"color": |link_hover|})),
+        // Moving the cursor to some other place to not create issues with next function run.
+        ("move-cursor-to", ".search-input"),
+    ]
+)
+
+call-function: ("check-no-result", {
+    "theme": "ayu",
+    "link": "rgb(57, 175, 215)",
+    "link_hover": "rgb(57, 175, 215)",
+})
+call-function: ("check-no-result", {
+    "theme": "dark",
+    "link": "rgb(0, 137, 255)",
+    "link_hover": "rgb(0, 137, 255)",
+})
+call-function: ("check-no-result", {
+    "theme": "light",
+    "link": "rgb(56, 115, 173)",
+    "link_hover": "rgb(56, 115, 173)",
+})