rustdoc: add test cases, and fix, search tabs

Author: notriddle

src/librustdoc/html/static/js/search.js

@@ -2334,11 +2334,16 @@ ${item.displayPath}<span class="${type}">${name}</span>\
     }
 
     function makeTabHeader(tabNb, text, nbElems) {
+        // https://blog.horizon-eda.org/misc/2020/02/19/ui.html
+        let fmtNbElems =
+            nbElems < 10  ? `\u{2007}\u{2007}(${nbElems})` :
+            nbElems < 100 ? `\u{2007}(${nbElems})` :
+            `(${nbElems})`;
         if (searchState.currentTab === tabNb) {
             return "<button class=\"selected\">" + text +
-                   " <span class=\"count\">(" + nbElems + ")</span></button>";
+                   "<span class=\"count\">" + fmtNbElems + "</span></button>";
         }
-        return "<button>" + text + " <span class=\"count\">(" + nbElems + ")</span></button>";
+        return "<button>" + text + "<span class=\"count\">" + fmtNbElems + "</span></button>";
     }
 
     /**

tests/rustdoc-gui/search-tab.goml

@@ -1,5 +1,5 @@
 // Checking the colors of the search tab headers.
-go-to: "file://" + |DOC_PATH| + "/test_docs/fn.foo.html?search=something"
+go-to: "file://" + |DOC_PATH| + "/test_docs/fn.foo.html?search=foo"
 show-text: true
 
 define-function: (
@@ -74,3 +74,14 @@ call-function: ("check-colors", {
     "border_top_selected": "2px solid #0089ff",
     "border_top_hover": "2px solid #0089ff",
 })
+
+// Check the size and count in tabs
+assert-text: ("#search-tabs > button:nth-child(1) > .count", " (23)")
+assert-text: ("#search-tabs > button:nth-child(2) > .count", "  (4)")
+assert-text: ("#search-tabs > button:nth-child(3) > .count", "  (0)")
+store-property: ("#search-tabs > button:nth-child(1)", {"offsetWidth": buttonWidth})
+assert-property: ("#search-tabs > button:nth-child(2)", {"offsetWidth": |buttonWidth|})
+assert-property: ("#search-tabs > button:nth-child(3)", {"offsetWidth": |buttonWidth|})
+store-property: ("#search-tabs > button:nth-child(1) > .count", {"offsetWidth": countWidth})
+assert-property: ("#search-tabs > button:nth-child(2) > .count", {"offsetWidth": |countWidth|})
+assert-property: ("#search-tabs > button:nth-child(3) > .count", {"offsetWidth": |countWidth|})