diff --git a/spec/AllocationManagerImpl.spec.ts b/spec/AllocationManagerImpl.spec.ts
new file mode 100644
index 0000000..cad4d81
--- /dev/null
+++ b/spec/AllocationManagerImpl.spec.ts
@@ -0,0 +1,41 @@
+import Allocation from '../src/Allocation';
+import AllocationManagerImpl from '../src/AllocationManagerImpl';
+import ArrayModelStore from '../src/ArrayModelStore';
+import Developer from '../src/Developer';
+import Project from '../src/Project';
+import Technology from '../src/Technology';
+
+describe('AllocationManagerImpl', function () {
+    describe('getFreeDevelopersForTechnology', function () {
+        it('should give empty array when no developer exists for technology', function () {
+            const developerStore = new ArrayModelStore<Developer>();
+            const projectStore = new ArrayModelStore<Project>();
+            const allocationStore = new ArrayModelStore<Allocation>();
+            const alloc_manager = new AllocationManagerImpl(projectStore, developerStore, allocationStore);
+
+            const freeDevelopersForJava = alloc_manager.getFreeDevelopersForTechnology(Technology.JAVA);
+
+            expect(freeDevelopersForJava).toEqual([]);
+        });
+    });
+
+    describe('getFreeDevelopersForTechnology', function () {
+        it('should give free developers for technology', function () {
+            const developerStore = new ArrayModelStore<Developer>();
+            developerStore.add(new Developer({ id: 1, name: 'Kick', knownTechnologies: [Technology.JAVA] }));
+            developerStore.add(new Developer({ id: 2, name: 'Nick', knownTechnologies: [Technology.JAVA] }));
+
+            const projectStore = new ArrayModelStore<Project>();
+            const allocationStore = new ArrayModelStore<Allocation>();
+            const alloc_manager = new AllocationManagerImpl(projectStore, developerStore, allocationStore);
+
+            const freeDevelopersForJava = alloc_manager.getFreeDevelopersForTechnology(Technology.JAVA);
+
+            expect(freeDevelopersForJava).toEqual([
+                new Developer({ id: 1, name: 'Kick', knownTechnologies: [Technology.JAVA] }),
+                new Developer({ id: 2, name: 'Nick', knownTechnologies: [Technology.JAVA] }),
+            ]);
+        });
+    });
+
+});
diff --git a/src/AllocationManager.ts b/src/AllocationManager.ts
index 0070cdd..e653997 100644
--- a/src/AllocationManager.ts
+++ b/src/AllocationManager.ts
@@ -8,6 +8,3 @@ export default interface AllocationManager {
     getFreeDevelopersForTechnology(technology: Technology): Developer[];
     allocateDeveloperToProjectForTechnology(developer: Developer, project: Project, technology: Technology): void;
 }
-
-
-
diff --git a/src/AllocationManagerImpl.ts b/src/AllocationManagerImpl.ts
index 999137f..4b41b88 100644
--- a/src/AllocationManagerImpl.ts
+++ b/src/AllocationManagerImpl.ts
@@ -1,42 +1,45 @@
 import Allocation from './Allocation';
 import AllocationManager from './AllocationManager';
 import Developer from './Developer';
+import ModelStore from './ModelStore';
 import Project from './Project';
-import { allocationStore, developerStore, projectStore } from './stores';
 import Technology from './Technology';
 
 export default class AllocationManagerImpl implements AllocationManager {
 
-    constructor() { }
+    constructor(
+        private projectStore: ModelStore<Project>,
+        private developerStore: ModelStore<Developer>,
+        private allocationStore: ModelStore<Allocation>) { }
 
     getUnfulfilledRequirementsForProject(projectId: number): Technology[] {
-        const requiredTechnologies = projectStore.getById(projectId).requiredTechnologies;
+        const requiredTechnologies = this.projectStore.getById(projectId).requiredTechnologies;
         const fulfilledTechnologies = new Set(this.getFulfilledRequirementsForProject(projectId));
         return requiredTechnologies.filter(technology => !fulfilledTechnologies.has(technology));
     }
 
     getAllocatedDeveloperTechnologiesForProject(projectId: number): { developerId: number, technology: Technology }[] {
-        return allocationStore
+        return this.allocationStore
             .filter(alloc => alloc.projectId === projectId)
             .map(alloc => ({ developerId: alloc.developerId, technology: alloc.technology }));
     }
 
     getFreeDevelopersForTechnology(technology: Technology): Developer[] {
-        return developerStore
+        return this.developerStore
             .filter(developer => developer.knownTechnologies.some(t => t === technology))
             .filter(developer => !this.getAllocatedDeveloperIds().some(id => id === developer.id));
     }
 
     allocateDeveloperToProjectForTechnology(developer: Developer, project: Project, technology: Technology): void {
-        allocationStore.add(new Allocation(developer.id, project.id, technology));
+        this.allocationStore.add(new Allocation(developer.id, project.id, technology));
     }
 
     private getAllocatedDeveloperIds(): number[] {
-        return allocationStore.all().map(developer => developer.id);
+        return this.allocationStore.all().map(developer => developer.id);
     }
 
     private getFulfilledRequirementsForProject(projectId: number): Technology[] {
-        return allocationStore
+        return this.allocationStore
             .filter(alloc => alloc.projectId === projectId)
             .map(alloc => alloc.technology);
     }
diff --git a/src/Developer.ts b/src/Developer.ts
index 361fb56..97aa026 100644
--- a/src/Developer.ts
+++ b/src/Developer.ts
@@ -4,4 +4,9 @@ import Technology from './Technology';
 export default class Developer extends Model {
     name: string;
     knownTechnologies: Technology[];
+
+    constructor(obj?: Partial<Developer>) {
+        super();
+        Object.assign(this, obj);
+    }
 }
diff --git a/src/Technology.ts b/src/Technology.ts
index 5fd849f..11cf75d 100644
--- a/src/Technology.ts
+++ b/src/Technology.ts
@@ -1,3 +1,7 @@
-type Technology = string;
+enum Technology {
+    JAVA,
+    PYTHON,
+    JAVASCRIPT,
+}
 
 export default Technology;
diff --git a/src/index.ts b/src/index.ts
index 4700047..ac3f702 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,10 +1,11 @@
 import Developer from "./Developer";
 import { developerStore } from "./stores";
+import Technology from "./Technology";
 
 const d = new Developer();
 
 d.id = 1;
-d.knownTechnologies = ['java', 'python'];
+d.knownTechnologies = [Technology.JAVA, Technology.PYTHON];
 
 developerStore.add(d);
 
diff --git a/src/mockData.ts b/src/mockData.ts
index ee697b6..07eabfb 100644
--- a/src/mockData.ts
+++ b/src/mockData.ts
@@ -1,24 +1,26 @@
+import Technology from './Technology';
+
 const MOCK_DATA = {
     DEVELOPERS: [
         {
             id: 1,
             name: 'Kick Buttowski',
-            knownTechnologies: ['java', 'python', 'javascript'],
+            knownTechnologies: [Technology.JAVA, Technology.PYTHON, Technology.JAVASCRIPT],
         },
         {
             id: 2,
             name: 'Courage C.D',
-            knownTechnologies: ['python'],
+            knownTechnologies: [Technology.PYTHON],
         },
     ],
     PROJECTS: [
         {
             id: 1,
-            requiredTechnologies: ['java']
+            requiredTechnologies: [Technology.JAVA]
         },
         {
             id: 2,
-            requiredTechnologies: ['python', 'javascript']
+            requiredTechnologies: [Technology.PYTHON, Technology.JAVASCRIPT]
         }
     ]
 };