[Composition] Disallow composition for leaf types

Disallow composition for domain object types which will
not have a composition property; WTD-1221.

platform/containment/test/CompositionModelPolicySpec.js

@@ -0,0 +1,26 @@
+/*global define,Promise,describe,it,expect,beforeEach,waitsFor,jasmine*/
+
+define(
+    ["../src/CompositionModelPolicy"],
+    function (CompositionModelPolicy) {
+        "use strict";
+
+        describe("The composition model policy", function () {
+            var mockType,
+                policy;
+
+            beforeEach(function () {
+                mockType = jasmine.createSpyObj('type', ['getInitialModel']);
+                policy = new CompositionModelPolicy();
+            });
+
+            it("only allows composition for types which will have a composition property", function () {
+                mockType.getInitialModel.andReturn({});
+                expect(policy.allow(mockType)).toBeFalsy();
+                mockType.getInitialModel.andReturn({ composition: [] });
+                expect(policy.allow(mockType)).toBeTruthy();
+            });
+        });
+
+    }
+);

platform/containment/test/CompositionMutabilityPolicySpec.js

@@ -35,7 +35,7 @@ define(
                 policy = new CompositionMutabilityPolicy();
             });
 
-            it("only allows composition for types which will have a composition capability", function () {
+            it("only allows composition for types which can be created/modified", function () {
                 expect(policy.allow(mockType)).toBeFalsy();
                 mockType.hasFeature.andReturn(true);
                 expect(policy.allow(mockType)).toBeTruthy();

platform/containment/test/suite.json

@@ -1,6 +1,7 @@
 [
     "CapabilityTable",
     "ComposeActionPolicy",
+    "CompositionModelPolicy",
     "CompositionMutabilityPolicy",
     "CompositionPolicy",
     "ContainmentTable"