query: fix ending backslash in query serialization

We now lose the ending backslash during the serialization
in order to build a valid query string.

Stringifying `{type: "simple", value: "hello\\"}` results :
- before ` "hello\"`, which is an invalid query string ;
- now ` "hello"`, which is ok.

src/queries/query.js

@@ -672,6 +672,13 @@
                         "Argument 1 is not a search text or a parsable object");
   };
 
+  function sanitizeQueryValue(value) {
+    if (typeof value === "string") {
+      return value.replace(/((?:\\\\)*)\\$/, "$1");
+    }
+    return value;
+  }
+
   function objectToSearchText(query) {
     var i = 0,
       query_list = null,
@@ -680,7 +687,8 @@
       common_key = "";
     if (query.type === "simple") {
       return (query.key ? query.key + ": " : "") +
-        (query.operator || "") + ' "' + query.value + '"';
+        (query.operator || "") +
+        ' "' + sanitizeQueryValue(query.value) + '"';
     }
     if (query.type === "complex") {
       query_list = query.query_list;
@@ -711,7 +719,7 @@
         for (i = 0; i < query_list.length; i += 1) {
           string_list.push(
             (query_list[i].operator || "") +
-              ' "' + query_list[i].value + '"'
+              ' "' + sanitizeQueryValue(query_list[i].value) + '"'
           );
         }
       } else {

test/queries/tests.js

@@ -359,6 +359,24 @@
       "{complex query without operator}.toString()"
     );
 
+    deepEqual(
+      jIO.QueryFactory.create({
+        "type": "simple",
+        "value": "b\\a"
+      }).toString(),
+      " \"b\\a\"",
+      "{simple query with backslash}.toString()"
+    );
+
+    deepEqual(
+      jIO.QueryFactory.create({
+        "type": "simple",
+        "value": "b\\"
+      }).toString(),
+      " \"b\"",
+      "{simple query ending with backslash}.toString()"
+    );
+
   });
 
   test('Docs with space, tab, and newline', function () {