src/app/input-component-manager.service.spec.ts

@@ -1,6 +1,7 @@
-import { TestBed, inject } from '@angular/core/testing';
+import {inject, TestBed} from '@angular/core/testing';
 
-import { InputComponentManagerService } from './input-component-manager.service';
+import {InputComponentManagerService} from './input-component-manager.service';
+import {Step} from './step';
 
 describe('InputComponentManagerService', () => {
   beforeEach(() => {
@@ -12,4 +13,59 @@ describe('InputComponentManagerService', () => {
   it('should be created', inject([InputComponentManagerService], (service: InputComponentManagerService) => {
     expect(service).toBeTruthy();
   }));
+
+  it('should create a component if requesting the first one',
+    inject([InputComponentManagerService], (service: InputComponentManagerService) => {
+      const firstStep: Step = service.getFirst();
+      expect(firstStep).toBeTruthy();
+      expect(service.getFirst()).toBe(firstStep);
+      expect(service.getAllComponents().length).toEqual(1);
+    })
+  );
+
+  it('must not add a null Step', inject([InputComponentManagerService], (service: InputComponentManagerService) => {
+    expect(() => service.register(null)).toThrowError();
+    expect(service.getAllComponents().length).toEqual(0);
+  }));
+
+  it('must not add an undefined Step', inject([InputComponentManagerService], (service: InputComponentManagerService) => {
+    expect(() => service.register(undefined)).toThrowError();
+    expect(service.getAllComponents().length).toEqual(0);
+  }));
+
+  it('should register new Steps', inject([InputComponentManagerService], (service: InputComponentManagerService) => {
+    service.register(new Step(99));
+    expect(service.getAllComponents().length).toEqual(1);
+    service.register(new Step(100));
+    expect(service.getAllComponents().length).toEqual(2);
+  }));
+
+  it('should return a new step if the next step doesn\'t exist',
+    inject([InputComponentManagerService], (service: InputComponentManagerService) => {
+      // arrange
+      const firstStep: Step = new Step(0);
+      service.register(firstStep);
+
+      // act
+      const nextStep: Step = service.getNext(firstStep);
+
+      // assert
+      expect(service.getAllComponents().length).toEqual(2);
+      expect(nextStep.index).toEqual(1);
+    })
+  );
+
+  it('should return the next step if requested', inject([InputComponentManagerService], (service: InputComponentManagerService) => {
+    // arrange
+    const firstStep: Step = new Step(0);
+    const nextStep: Step = new Step(1);
+    service.register(firstStep);
+    service.register(nextStep);
+
+    // act
+    const requestedStep: Step = service.getNext(firstStep);
+    // assert
+    expect(service.getAllComponents().length).toEqual(2);
+    expect(requestedStep).toEqual(nextStep);
+  }));
 });

src/app/input-component-manager.service.ts

@@ -11,6 +11,9 @@ export class InputComponentManagerService {
   }
 
   public register(component: Step): void {
+    if (!component) {
+      throw new Error('component to add must not be empty or undefined');
+    }
     this.components.push(component);
   }