Spring Boot allows us to replace our `application.properties` files with YAML equivalents. However, I seem to hit a snag with my tests. If I annotate my `TestConfiguration` (a simple Java config), it is expecting a properties file.

For example this doesn't work:
`@PropertySource(value = "classpath:application-test.yml")`

If I have this in my **YAML** file:

```
db:
  url: jdbc:oracle:thin:@pathToMyDb
  username: someUser
  password: fakePassword

```

And I'd be leveraging those values with something like this:

```java
@Value("${db.username}") String username

```

However, I end up with an error like so:

```java
Could not resolve placeholder 'db.username' in string value "${db.username}"

```

How can I leverage the YAML goodness in my tests as well?