Fix error when attempting to render layoutData without parent in flush

This error only occured if a flush caused a layoutData to be rendered
when the widget has no parent. It worked fine outside a flush or when
only the sibling is missing.

This is the least invasive solution. I will come back to this code later
and refactor.

Fix #303

Change-Id: Ic2490b49b382c8c8ae42f19d6f6cd675b1e022a8

src/js/Layout.js

@@ -85,7 +85,7 @@
 
   var emptyParent = {
     children: function() {
-      return null;
+      return [];
     }
   };
 

test/js/Layout.spec.js

@@ -141,21 +141,36 @@ describe("Layout:", function() {
       expect(layoutData.top).toEqual([other, 42]);
     });
 
-    it("throws if selector does not resolve", function() {
+    it("throws if selector does not resolve due to missing sibling", function() {
       other.dispose();
 
       expect(function() {
         encode({left: 23, right: "#other", top: ["#other", 42]}, widget);
       }).toThrow();
     });
 
-    it("replaces unresolved selector with 0 if forced ", function() {
+    it("throws if selector does not resolve due to missing parent", function() {
+      widget = tabris.create("TestType");
+
+      expect(function() {
+        encode({left: 23, right: "#other", top: ["#other", 42]}, widget);
+      }).toThrow();
+    });
+
+    it("replaces selector not resolved due to missing sibling with 0", function() {
       other.dispose();
 
       expect(encode({left: 23, right: "#noone", top: ["#noone", 42]}, widget, true))
         .toEqual({left: 23, right: [0, 0], top: [0, 42]});
     });
 
+    it("replaces selector not resolved due to missing parent with 0", function() {
+      widget = tabris.create("TestType");
+
+      expect(encode({left: 23, right: "#noone", top: ["#noone", 42]}, widget, true))
+        .toEqual({left: 23, right: [0, 0], top: [0, 42]});
+    });
+
   });
 
 });

test/js/Widgets.spec.js

@@ -244,25 +244,41 @@ describe("Widgets", function() {
       expect(call.properties.layoutData).toEqual(expected);
     });
 
-    it("SET layoutData again until selector resolves", function() {
+    it("SET layoutData again until selector resolves by adding sibling", function() {
       other.dispose();
 
       widget.set("layoutData", {right: "#other"});
-      var calls1 = nativeBridge.calls({op: "set"});
-      nativeBridge.resetCalls();
-      var calls2 = nativeBridge.calls({op: "set"});
-      nativeBridge.resetCalls();
+      var withoutSibling = nativeBridge.calls({op: "set"});
+      var retry = nativeBridge.calls({op: "set"});
       other = tabris.create("TestType", {id: "other"}).appendTo(parent);
-      var calls3 = nativeBridge.calls({op: "set"});
+      var withSibling = nativeBridge.calls({op: "set"});
+      var noRetry = nativeBridge.calls({op: "set"});
+
+      expect(withoutSibling.length).toBe(1);
+      expect(retry.length).toBe(1);
+      expect(withSibling.length).toBe(2);
+      expect(noRetry.length).toBe(2);
+      expect(withoutSibling[0].properties.layoutData).toEqual({right: [0, 0]});
+      expect(withSibling[1].properties.layoutData).toEqual({right: [other.cid, 0]});
+    });
+
+    it("SET layoutData again until selector resolves by setting parent", function() {
+      widget = tabris.create("TestType");
       nativeBridge.resetCalls();
-      var calls4 = nativeBridge.calls({op: "set"});
-
-      expect(calls1.length).toBe(1);
-      expect(calls2.length).toBe(0);
-      expect(calls3.length).toBe(1);
-      expect(calls4.length).toBe(0);
-      expect(calls1[0].properties.layoutData).toEqual({right: [0, 0]});
-      expect(calls3[0].properties.layoutData).toEqual({right: [other.cid, 0]});
+
+      widget.set("layoutData", {right: "#other"});
+      var withoutParent = nativeBridge.calls({op: "set"});
+      var retry = nativeBridge.calls({op: "set"});
+      widget.appendTo(parent);
+      var withParent = nativeBridge.calls({op: "set"});
+      var noRetry = nativeBridge.calls({op: "set"});
+
+      expect(withoutParent.length).toBe(1);
+      expect(retry.length).toBe(1);
+      expect(withParent.length).toBe(2);
+      expect(noRetry.length).toBe(2);
+      expect(withoutParent[0].properties.layoutData).toEqual({right: [0, 0]});
+      expect(withParent[1].properties.layoutData).toEqual({right: [other.cid, 0]});
     });
 
   });