Angular test component with service dependencies

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angular test component with service dependencies

Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I'm trying to set up a test for my service using TestBed. That service has some dependencies of other services. I've created. Problem is when I try to use these stubs in the test it still seems like the test methods use the real service and not the test. Here's my setup the fake names are just for this thread :. I understand the error, that's because behaviorSubjectTest property is on the stub and not the real service.

But why doesn't it use the stub service when I listed it as a useClass in the providers? What am I doing wrong? When I see what's available on serviceDependency1Stub I see all the methods and properties on the real service and not the stub.

This happened after updating to Angular 9. Earlier we used the. Then it was set up like this:. I guess the setup from start was wrong, but not exposed before now after changing to. I've looked at the documentation but I can't find any good examples on testing service with dependencies. If anyone could help me and point me in the right direction I would appreciate that. Learn more.

Testing service with dependencies Ask Question. Asked 4 days ago. Active 4 days ago. Viewed 23 times. Is the error coming at runtime, or from TypeScript?

You've typed the stub variable as the dependency itself, so typescript won't give you access to the extra stub properties. From TypeScript. The error shows up in the editor. If you're referring to the let variable I edited and renamed it now to make it more clear. I don't actually use these names, just replaced the real names to hide the real business logic.

Yes, let stubbedService: ServiceDependency1; - ServiceDependency1 presumably doesn't have the props the stub adds. So that property would be behaviorSubjectTest. The variable name was different in the real service. I've changed it now so the property in the real service and the stubbed service is the same. The only difference now is that the property in the real service is private and the one in the stub is public. Now I get this error: Property 'behaviorSubjectTest' is private and only accessible within class 'ServiceDependency1'.

Why would it? You've told the compiler the variable you've assigned the stub to is actually the real thing.October 5, 8 min read Have you been looking for a way to test what you have built based on user behavior?

Writing tests for different coupling blocks in your application will help demonstrate how these blocks behave. One of the easiest ways to test the strengths of these blocks is writing a test for each of them. Writing a test for your blocks components, services, etc. When you create a new project with the cli ng new appNamea default component and test file are added.

Also, for those that always like a shortcut method like me, a test script is always created alongside any component module service, component you create using Angular cli. This test script which ends with.

You might be wondering, how can we simulate a user behavior by simply writing a test, even though the project is being rendered in a browser? As we proceed, I will demonstrate how we can simulate the app running on a browser.

Karma also ensures the result of the test is printed out either in the console or in file log.

This is the only block that runs before any other block it. The same logic applies to other test declaration. You might not necessarily compile your component if you are using webpack:. The fixture.

Testing Angular 2+ services with dependencies

The third block demonstrates how you can have access to the properties of the created component AppComponent. The only property added by default is the title. You can easily check if the title you set has changed or not from the instance of the component AppComponent created:. The fourth block demonstrates how the test behaves in the browser environment.

After creating the component, an instance of the created component detectChanges to simulate running on the browser environment is called. Now that you have familiarized yourself with the basics of testing a component. Services often depend on other services that Angular injects into the constructor. The injected service handles the manipulation of all operations add, remove, fetch.

angular test component with service dependencies

Just like the way we access an element with its CSS property, we can also access an element by its class name. This operation is best treated as an asynchronous task. Angular also ensures test results are viewed in your browser. This will give a better visualization of the test results. LogRocket is like a DVR for web apps, recording literally everything that happens on your site including network requests, JavaScript errors, and much more.

Instead of guessing why problems happen, you can aggregate and report on what state your application was in when an issue occurred. The LogRocket NgRx plugin logs Angular state and actions to the LogRocket console, giving you context around what led to an error, and what state the application was in when an issue occurred. Modernize how you debug your Angular apps - Start monitoring for free.

A great Post! Reply 3. Mesh Seun Follow Software engineer. We made a custom demo for. No really. Click here to check it out. Click here to see the full demo with network requests. Experience your Angular apps exactly how a user does Debugging Angular applications can be difficult, especially when users experience issues that are difficult to reproduce. Uncategorized angular.I'm trying to set up a test for my service using TestBed.

That service has some dependencies of other services. I've created. Problem is when I try to use these stubs in the test it still seems like the test methods use the real service and not the test. Here's my setup the fake names are just for this thread :. I understand the error, that's because behaviorSubjectTest property is on the stub and not the real service. But why doesn't it use the stub service when I listed it as a useClass in the providers?

What am I doing wrong? When I see what's available on serviceDependency1Stub I see all the methods and properties on the real service and not the stub. This happened after updating to Angular 9. Earlier we used the. Then it was set up like this:. I guess the setup from start was wrong, but not exposed before now after changing to. I've looked at the documentation but I can't find any good examples on testing service with dependencies.

If anyone could help me and point me in the right direction I would appreciate that. Home angular Testing service with dependencies angular typescript testing testbed I'm trying to set up a test for my service using TestBed.In short, tests are considered isolated when a fresh instance of your service class is created before each test, like so:. The simplest test we can write, if we are using the TestBed would look something like this:. As you can see, the TestBed tests require a bit more setup up front, but individual specs it s are not any different.

So why would you ever use the TestBed for your service tests? There are advantages to that approach if your service has dependencies. As soon as you add even one dependency to your service, you need to also add it to your tests. In case of isolated tests, you will need to pass an instance of an injectable dependency class into the constructor of your service instantiation.

But this approach would only work if MyServiceDependency does not have any dependencies itself. If it does, you would obviously need to pass them in as well, and so on and so forth.

angular test component with service dependencies

This can get out of hand really quickly. With this approach it is also harder to mock and stub dependencies, which is something we would definitely prefer to do, as we only want to test a specific service, not the dependencies. That gets rid of the error, but we are still faced with the same problems as we did with isolated tests:. The solution to both of these points would be to create a stub of MyServiceDependency and inject it instead of the real MyServiceDependency. Something we can do very easily with the TestBed approach.

First, we need to create a stub class of our MyServiceDependency class that we will be injecting instead of the real MyServiceDependency class. Even if the class is blank, i. As you write tests for your service, you will sooner or later encounter some code that uses the dependency, like calling a method or accessing a property on it, which will require you to add it to your stub. Potential test for this method would be checking that getSomeValue method is called on myServiceDependency.

However, because we are injecting a stub into our testing module, we need to make sure that when doSomething will be called within our tests - getSomeValue method is present on the stub. Simply adding it to our stub will do. Now, we can easily set up a spy on getSomeValue and assert that it was actually called during the execution of doSomethingresulting in the following full spec file:. In case you ever forget to add a method to a stub, and then try to spy on that method, you will be greeted with an Error: getSomeValue method does not exist error.

Sample application demonstrating these concepts in a more realistic scenario can be found here. Service Dependencies As soon as you add even one dependency to your service, you need to also add it to your tests.

Stubbing a dependency First, we need to create a stub class of our MyServiceDependency class that we will be injecting instead of the real MyServiceDependency class. Share this post Tweet.In this blogpost I want to describe how to use the useClassuseValueuseFactoryuseExisting providers in the new treeshakable providers from Angular.

After this blogpost you should have an example how to use those four providers and have an idea what to do with it in case they are a solution to some problems you might face when developing Angular applications.

Everybody is talking about the providedIn property of the configuration object which can be passed to the Injectable decorator of the Angular services. Basically this means that a service can provide himself to a specific injector and is treeshakeable. That means if the service is not used it will get shaken out to get your application smaller and faster. Actually this is a pretty good thing and was mentioned many times already.

But the providedIn property is only one property of many which can describe how your service should be provided to your application.

Testing AngularJS Services With Dependencies

We got. Let us start having the AngularCLI installed and scaffolding a new project with ng new myNewPlayground and wait for it to finish. After it did we can cd into the folder with cd myNewPlayground and create a new service with ng generate service Test.

The AngularCLI will create a new service for us looking a little something like this:. So we added a method which basically does nothing else than logging something out to the console.

Nothing spectacular so far. Again, we are just using the service, calling the method which logs something out. We will use the method to see which service is gonna be used later.

angular test component with service dependencies

So we see the providedIn already, which works, which is great, but we can use useClasstoo in this case. Note that this is a normal typescript class. There is no Angular reference to this class, no decorator, nothing so far. Lets use the useClass provider now. Modify the configuration object to our decorator like the following.

We are telling Angular now that if we are asking for this service anywhere in our application we want to use a different service instead! If we check the console we see that we are working with the instance of TestService2 now. With useFactory we can use a factory at runtime to decide which kind of service we want to return if it got requested by any other class in our application. You could use interfaces as contracts and abstract classes here for example. So lets create a new service first with has the same method as the other services and return a new instance in a function then.

Aditionally lets a a method as factory which we can pass to the useFactory provider. This factory pattern comes out of the box which is very powerful and gives your great possibilities when it comes to cross platform development.

Sometimes you have to add some dependencies to the factory because you need it to decide whether to return serviceA or serviceB. However, you can add the dependencies with the deps property on the configuration object. Alright, so we can use the deps property like usual. You might get the idea that in relation to the others useValue is providing a single value. This way you can pass single values around and inject them into your components, services, etc. To test the service now - remember we did not change our app.Photo by deepakrit on Pixabay.

Dependency injection is a key feature of Angular. This flexible approach makes our declarables and class-based services easier to test in isolation. Tree-shakable dependencies remove the layer of indirection that is Angular modules, but how do we test their tree-shakable providers? Some components have browser-specific features. Just kidding! We have to be careful not to get overly confident about complex integration scenarios.

Simplified Angular unit testing

We should always make sure to perform QA Quality Assurance tests in environments as close to production as possible. This means running the application in a real Internet Explorer 11 browser. The Angular testing utilities enable us to fake dependencies for the purpose of testing.

To test the Internet Explorer 11 flag provider in isolation, we can replace the userAgentToken with a fake value. We notice that the user agent string provider extracts the relevant information from the platform-specific Navigator API. Depending on the test runner we use, the Navigator API might not even be available in the testing environment. To be able to create fake navigator configurations, we create a dependency injection token for the Navigator API.

We can use these fake configurations to simulate user contexts during development and testing. What we test and how we test it should be part of our testing strategy. In more integrated component tests, we should be able to rely on most of the providers created as part of our dependency injection tokens. The Angular testing utilities give us more than one way to resolve a dependency.

The inject function allows us to resolve multiple dependencies by listing their tokens in an array that we pass as an argument. Every dependency injection token is resolved and available to the test case function as a parameter. I have created a StackBlitz project with all the tests from this article running in Jasmine. As seen in the test report, the test works. We have successfully faked the native Navigator API for the purpose of testing.

When we are using the Angular testing module without declarables, we can usually override a provider several times even within the same test case. It resolves dependencies just before the test case function body is executed. We can replace the token provider in beforeAll and beforeEach hooks using the static methods TestBed.It really is surprising sometimes to realize just how much you can do with Facebook - there are a TON of options that really allow you to experiment and work outside the box.

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Testing with Mocks & Spies

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Testing service with dependencies

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