Closes #8123: Fix plus-handling (+) in search terms for basic html theme search

Note, that the default splitter will not index +, so this isn't of much of much use, unless
the splitter of the search-language is reconfigured.

tests/js/doctools.js

@@ -12,6 +12,10 @@ describe('jQuery extensions', function() {
       expect(jQuery.urldecode(test_encoded_string)).toEqual(test_decoded_string);
     });
 
+    it('+ should result in " "', function() {
+      expect(jQuery.urldecode('+')).toEqual(' ');
+    });
+
   });
 
   describe('getQueryParameters', function() {

tests/js/searchtools.js

@@ -0,0 +1,32 @@
+describe('Basic html theme search', function() {
+
+  describe('terms search', function() {
+
+    it('should find "C++" when in index', function() {
+      index = {
+        docnames:["index"],
+        filenames:["index.rst"],
+        terms:{'c++':0},
+        titles:["<no title>"],
+        titleterms:{}
+      }
+      Search.setIndex(index);
+      searchterms = ['c++'];
+      excluded = [];
+      terms = index.terms;
+      titleterms = index.titleterms;
+
+      hits = [[
+        "index",
+        "<no title>",
+        "",
+        null,
+        2,
+        "index.rst"
+      ]];
+      expect(Search.performTermsSearch(searchterms, excluded, terms, titleterms)).toEqual(hits);
+    });
+
+  });
+
+});