[HTML search] Add preparatory test coverage before anticipated partia…

…l-search refactoring.

tests/js/roots/partial/index.rst

@@ -1,7 +1,7 @@
 sphinx_utils module
 ===================
 
-Partial (also known as "prefix") matches on document titles should be possible
+Partial matches on document titles and document terms should both be possible
 using the JavaScript search functionality included when HTML documentation
 projects are built.
 

tests/js/searchtools.js

@@ -78,6 +78,24 @@ describe('Basic html theme search', function() {
       expect(Search.performTermsSearch(searchterms, excluded, terms, titleterms)).toEqual(hits);
     });
 
+    it('should partially-match within "possible" when in term index', function() {
+      eval(loadFixture("partial/searchindex.js"));
+
+      [_searchQuery, searchterms, excluded, ..._remainingItems] = Search._parseQuery('ossibl');
+      terms = Search._index.terms;
+      titleterms = Search._index.titleterms;
+
+      hits = [[
+        "index",
+        "sphinx_utils module",
+        "",
+        null,
+        2,
+        "index.rst"
+      ]];
+      expect(Search.performTermsSearch(searchterms, excluded, terms, titleterms)).toEqual(hits);
+    });
+
   });
 
   describe('aggregation of search results', function() {