diff --git a/src/app/service-graph/services/node-positioner.service.spec.ts b/src/app/service-graph/services/node-positioner.service.spec.ts
new file mode 100644
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--- /dev/null
+++ b/src/app/service-graph/services/node-positioner.service.spec.ts
@@ -0,0 +1,128 @@
+
+/*
+ * Copyright 2017-present Open Networking Foundation
+
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+
+ * http://www.apache.org/licenses/LICENSE-2.0
+
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+import * as angular from 'angular';
+import 'angular-mocks';
+import 'angular-ui-router';
+import {IXosNodePositioner, XosNodePositioner} from './node-positioner.service';
+
+let service: IXosNodePositioner;
+
+let scope: ng.IRootScopeService;
+
+let constraints: string = '';
+
+let mockResource = {
+  query: () => {
+    return;
+  }
+};
+
+const mockModelRest = {
+  getResource: jasmine.createSpy('ModelRest.getResource')
+    .and.returnValue(mockResource)
+};
+
+describe('The XosNodePositioner service', () => {
+
+  beforeEach(() => {
+    angular.module('XosNodePositioner', [])
+      .service('XosNodePositioner', XosNodePositioner)
+      .value('ModelRest', mockModelRest);
+
+    angular.mock.module('XosNodePositioner');
+  });
+
+  beforeEach(angular.mock.inject((
+    XosNodePositioner: IXosNodePositioner,
+    $rootScope: ng.IRootScopeService,
+    _$q_: ng.IQService) => {
+
+    service = XosNodePositioner;
+    scope = $rootScope;
+
+    spyOn(mockResource, 'query').and.callFake(() => {
+      const d = _$q_.defer();
+      d.resolve([{constraints}]);
+      return {$promise: d.promise};
+    });
+  }));
+
+  it('should position the nodes on the svg', (done) => {
+    const svg = {width: 300, height: 100};
+    const nodes = [
+      {data: {name: 'a'}},
+      {data: {name: 'b'}}
+    ];
+    constraints = '["a", "b"]';
+    service.positionNodes(svg, nodes)
+      .then((positioned) => {
+        expect(positioned[0].x).toBe(100);
+        expect(positioned[0].y).toBe(50);
+        expect(positioned[1].x).toBe(200);
+        expect(positioned[1].y).toBe(50);
+        done();
+      });
+
+    scope.$apply();
+  });
+
+  it('should position the nodes on the svg in vertical bundles', (done) => {
+    const svg = {width: 300, height: 90};
+    const nodes = [
+      {data: {name: 'a'}},
+      {data: {name: 'b'}},
+      {data: {name: 'c'}}
+    ];
+    constraints = '["a", ["b", "c"]]';
+    service.positionNodes(svg, nodes)
+      .then((positioned) => {
+        expect(positioned[0].x).toBe(100);
+        expect(positioned[0].y).toBe(45);
+        expect(positioned[1].x).toBe(200);
+        expect(positioned[1].y).toBe(30);
+        expect(positioned[2].x).toBe(200);
+        expect(positioned[2].y).toBe(60);
+        done();
+      });
+
+    scope.$apply();
+  });
+
+  it('should accept null as constraint to leave an empty space', (done) => {
+    const svg = {width: 300, height: 90};
+    const nodes = [
+      {data: {name: 'a'}},
+      {data: {name: 'b'}},
+      {data: {name: 'c'}}
+    ];
+    constraints = '[[null, "a"], ["b", "c"]]';
+    service.positionNodes(svg, nodes)
+      .then((positioned) => {
+        expect(positioned[0].x).toBe(100);
+        expect(positioned[0].y).toBe(60);
+        expect(positioned[1].x).toBe(200);
+        expect(positioned[1].y).toBe(30);
+        expect(positioned[2].x).toBe(200);
+        expect(positioned[2].y).toBe(60);
+        done();
+      });
+
+    scope.$apply();
+  });
+});