Spring Boot version 2.2.0.M6
change the value of spring.messages.basename in application.properties does not make any difference
demo.zip
In this demo,the test com.example.demo.DemoApplicationTests#contextLoads will always fail.
Make a breakpoint at resolveCodeWithoutArguments:151, org.springframework.context.support.ResourceBundleMessageSource#resolveCodeWithoutArguments
The getBasenameSet() will always return a set which only contain one element: "messages"
But if eval the getResourceBundle("msg", locale) at that point,it will return the correct thing.
Also
org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration.ResourceBundleCondition#getResources returns the correct thing.