[SEBA-537] Reading priority from ServiceGraphConstraints

Change-Id: I8f510f46d3d4f0df0e26896ad9d64920b62bbb50
diff --git a/src/app/service-graph/services/node-positioner.service.spec.ts b/src/app/service-graph/services/node-positioner.service.spec.ts
index c6308e9..7356e46 100644
--- a/src/app/service-graph/services/node-positioner.service.spec.ts
+++ b/src/app/service-graph/services/node-positioner.service.spec.ts
@@ -19,7 +19,7 @@
 import * as angular from 'angular';
 import 'angular-mocks';
 import 'angular-ui-router';
-import {IXosNodePositioner, XosNodePositioner} from './node-positioner.service';
+import {IXosNodePositioner, IServiceGraphConstraint,  XosNodePositioner} from './node-positioner.service';
 
 let service: IXosNodePositioner;
 
@@ -152,4 +152,22 @@
 
     scope.$apply();
   });
+
+  describe('the readConstraints method', () => {
+    it('should return the constraint with higher priority', () => {
+      const constraints: IServiceGraphConstraint[] = [
+        {
+          constraints: JSON.stringify(['foo', 'bar']),
+          priority: 10
+        },
+        {
+          constraints: JSON.stringify(['foo', 'bar', 'baz']),
+          priority: 20
+        }
+      ];
+      const fn = service['readConstraints']; // we need this as it's a private method
+      const res = fn(constraints);
+      expect(res).toEqual(['foo', 'bar', 'baz']);
+    });
+  });
 });