Setting Up a Test Context

For testing the weather service, 0:00 we're going to need to dive a bit deeper into the Spring Test Framework. 0:02 Currently, our application's WeatherServiceImpl, 0:05 let me open that WeatherServiceImpl. 0:08 Currently, this class depends on properties that are loaded 0:11 from a properties file, you see that with the PropertySource annotation. 0:14 As well as an Autowired bean in the Impl's superclass, 0:18 which you see here is the RestApiService and 0:22 the Autowired bean that it depends on is this RestTemplate bean. 0:25 Now, you recall from earlier in the workshop, I mentioned that RestTemplate is 0:31 a way that we can use the Spring Framework to call upon external APIs. 0:35 The problem with these Autowired fields, as well as anything that receives its 0:41 value from a value annotation that comes from a properties file, 0:46 is that since we aren't loading the entire application context right now, 0:50 these things will not be injected in our tests. 0:54 No worries though, the Spring Test Framework offers us an option. 1:00 We can load a test context by providing a test specific configuration class. 1:03 Let's add our weather service test and get started. 1:09 So I'm back in the test source folder and 1:12 I'm going to add a class for weather service test. 1:17 WeatherServiceTest. 1:21 For starters, we'll need to use Spring's JUnit runner so 1:25 we'll annotate the class with a RunWith annotation and 1:29 specify the SpringJunit4ClassRunner as the JUnit runner to be used for these tests. 1:33 And next, in order to trigger the loading of a test context, 1:41 we'll annotate this class with a ContextConfiguration annotation. 1:44 Now without specifying a class or to location as an annotation element 1:51 on this ContextConfiguration annotation, Spring will look for 1:54 classes annotated with the configuration annotation in the current class. 1:58 So let's add a static class within WeatherServiceTest. 2:03 So I will say Configuration and 2:07 call it public static class TestConfig. 2:11 Now to get those properties from api.properties, 2:18 I'll annotate this class with the same type of PropertySource annotation 2:21 that we saw in our WeatherServiceImpl class. 2:26 So PropertySource, and I'll say api.properties here, 2:29 and then I will add as a field an Autowired environment variable. 2:34 So, Autowired Environment, I'll call it env. 2:40 And remember that Autowired RestTemplate? 2:47 Let's make that available as a bean here. 2:49 So we'll call it Bean public RestTemplate, 2:52 there it is, restTemplate. 2:57 There we go. 3:02 Now we don't have to duplicate code from our AppConfig 3:04 where the production bean is located. 3:07 Let's head there to reconfigure some things. 3:09 So I'll open AppConfig.java. 3:10 And here is that RestTemplate bean right here. 3:14 You'll find that as you gain experience writing tests, 3:18 you'll get better at writing code that's more testable and test friendly. 3:21 So it's the code in this RestTemplate bean here that we'd rather not duplicate. 3:24 What we can do is make a static method that loads a default RestTemplate and 3:30 this production bean can utilize it. 3:34 Also, our test can then utilize it as well. 3:35 So, I will make that right here. 3:38 We'll say public static RestTemplate, and again, call it restTemplate. 3:40 Actually, I'll call this one defaultRestTemplate. 3:48 There we go, now I'll move all the code from here 3:53 down into the static method just like this. 3:56 With one exception, this static method doesn't need that 4:01 RequestFactory here since all that really does, if you look at this, 4:05 is it sets some connection and read timeout. 4:10 We won't need that for our tests for now. 4:14 Also, this would cause a problem for us since the method, 4:17 this ClientHttpRequestFactory method, that is an instance method and 4:20 this one is a static method so we could not call upon this method from here. 4:26 Now we can go back up here to the production bean and 4:33 tweak it a little bit so that it's still intact. 4:35 So I'll create a RestTemplate here, I'll just call it rt, and 4:37 call that default static method here. 4:41 And then, I'll just set the RequestFactory here calling upon 4:44 that method below, and this is an instance method so 4:49 it can indeed call this instance method down here. 4:52 Okay, everything's intact and 4:55 we now have this public static method where we can call it from the test class. 4:58 And I do see that I'm missing my return value here, so 5:03 I'll return that RestTemplate so that it is available as the bean. 5:07 So now that we have things set up in a more reusable manner in our application 5:12 code, let's switch back to the test. 5:15 I'm gonna close this file. 5:17 Okay, so in our test, we can now call upon that static method from AppConfig. 5:18 So I'll just return AppConfig.defaultRestTemplate, 5:25 good enough. 5:30 And another bean that we'll need to make available is a WeatherService bean, 5:31 we'll have to do this because it is our application class that contains 5:36 the ComponentScan annotation. 5:40 If I go to Application.java, I see the ComponentScan annotation which will tell 5:42 Spring that when it boots the application, remember, the application not the test, 5:46 when Spring boots the application, it'll scan the current package and 5:51 any sub packages of whatever application is located here. 5:56 So it'll scan all these sub packages for 6:00 any Spring components that are annotated with service, repository, or 6:02 any other Spring components that may be present in these packages. 6:07 Now this includes the service, 6:13 the WeatherServiceImpl that we are going to be testing. 6:16 This is annotated with a service, so when the application boots, 6:21 this WeatherService will be picked up as an auto-wireable bean and 6:25 we need that to be the case in our test as well. 6:30 So we'll need to construct and return the implementation ourselves. 6:34 Let's go back into our test and add that as a bean. 6:37 So we'll say Bean. 6:40 Public WeatherService weatherService. 6:44 And in here let's construct this. 6:51 So WeatherService, I'll just call it service = new, 6:53 I'll have to create the implementation myself and 7:00 pass in all those values that we can now grab from the env field. 7:04 Okay, so let me do that on separate lines here. 7:10 So I'll say env.getProperty, and the first one is weather.api.name. 7:13 And I'll just copy that and paste it a few times. 7:20 The next one we'll say is weather.api.key and 7:23 the next one is weather.api.host. 7:32 Cool, I've created my service implementation, 7:39 and now let's return it as the bean. 7:41 Cool, and at this point we're ready to write our test for 7:46 the weather service which is exactly what we're going to do in the next video. 7:48