Bug 1376128 - Ensure consistent return types from findElement; r=automatedtester

MozReview-Commit-ID: LnzsAHCMAxW

--HG--
extra : rebase_source : c9c44c07df3c29b3c5b80c507ab875278d597c90

testing/marionette/element.js

@@ -451,16 +451,22 @@ function filterLinks(node, predicate) {
 function findElement(using, value, rootNode, startNode) {
   switch (using) {
     case element.Strategy.ID:
+      {
         if (startNode.getElementById) {
           return startNode.getElementById(value);
         }
-      return element.findByXPath(rootNode, startNode, `.//*[@id="${value}"]`);
+        let expr = `.//*[@id="${value}"]`;
+        return element.findByXPath( rootNode, startNode, expr);
+      }
 
     case element.Strategy.Name:
+      {
         if (startNode.getElementsByName) {
           return startNode.getElementsByName(value)[0];
         }
-      return element.findByXPath(rootNode, startNode, `.//*[@name="${value}"]`);
+        let expr = `.//*[@name="${value}"]`;
+        return element.findByXPath(rootNode, startNode, expr);
+      }
 
     case element.Strategy.ClassName:
       // works for >= Firefox 3
@@ -479,7 +485,7 @@ function findElement(using, value, rootNode, startNode) {
           return link;
         }
       }
-      break;
+      return undefined;
 
     case element.Strategy.PartialLinkText:
       for (let link of startNode.getElementsByTagName("a")) {
@@ -487,7 +493,7 @@ function findElement(using, value, rootNode, startNode) {
           return link;
         }
       }
-      break;
+      return undefined;
 
     case element.Strategy.Selector:
       try {
@@ -495,18 +501,17 @@ function findElement(using, value, rootNode, startNode) {
       } catch (e) {
         throw new InvalidSelectorError(`${e.message}: "${value}"`);
       }
-      break;
 
     case element.Strategy.Anon:
       return rootNode.getAnonymousNodes(startNode);
 
     case element.Strategy.AnonAttribute:
       let attr = Object.keys(value)[0];
-      return rootNode.getAnonymousElementByAttribute(startNode, attr, value[attr]);
-
-    default:
-      throw new InvalidSelectorError(`No such strategy: ${using}`);
+      return rootNode.getAnonymousElementByAttribute(
+          startNode, attr, value[attr]);
   }
+
+  throw new InvalidSelectorError(`No such strategy: ${using}`);
 }
 
 /**