Using JUnit for testing System.exit() calls from application code can be tricky. This is because System.exit() terminates the JVM running it. If you’re running JUnit, this is the JUnit runner. If JUnit invokes System.exit() in application code it will end your test without deciding a success / fail status and will also terminate the test run.
Spring WebClient is the reactive replacement for the legacy RestTemplate. It has a more modern fluent API and first class support for Reactive Streams. This means it supports non-blocking, asynchronous responses.
However, the reactive WebClient does not yet have the mature test support that RestTemplate now has. There is not yet a standard recipe to test Spring WebClient applications. No doubt support will be improved in future versions but for now, here’s what works for me.
A standard unit testing problem is how to unit test code that has a dependency on dates or times. For example a method that returns a greeting according to the time of day:
public String timeOfDayGreeting() {
LocalTime now = LocalTime.now();
if (now.isBefore(LocalTime.NOON)) {
return "Good morning";
} else if (now.isBefore(LocalTime.of(18, 00))) {
return "Good afternoon";
} else {
return "Good evening";
}
}
If we were to call this method from a test fixture (say JUnit), it would return different values depending on when the test was run. This is not ideal. Unit tests should pass or fail consistently.
Here’s a simple solution for testing time based code.
This article demonstrates some more advanced test first React practices. Specifically, API calls and mocks.
React is a great choice for writing test first client side Javascript. The test ecosystem is mature enough to enable test first development of complex components. This article shows how to build a React component test first and introduces supporting test libraries Jest and Enzyme. In the next article we’ll look at more advanced testing including API testing and module mocking.
In previous articles, I’ve described how to test System.out with JUnit and how to test log4j with JUnit. This article describes how to test log4j2…
Following a recent article on how to Test System.out with JUnit, here’s a follow up on how to test log4J with JUnit. This article describes a technique to test log4J output in a JUnit test by adding a custom appender. This allows us to verify that log4j output contains expected Strings.
Edit: see also the follow up article on how to Test log4j with JUnit if you’re interested in specifically testing log output.
Just occasionally, it can be useful to verify output to System.out in a unit test. For example, if you’re testing application logging or if you’re using log output to sense some other behaviour. It can be tricky to properly mock behaviour of System.out but fortunately, it is possible to test System.out with JUnit.
Spring Boot 1.4.0 is now available. Among the enhancements are new mechanisms to build and test RestTemplates used to make calls to RESTful web services.