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Logging is an inevitable part of debugging. Well, at least in modern advanced programming languages and architectures. This is not thirty years ago, but now. Sometimes we track variables, although this is rarely done. More often we just print them to the console. In addition, we don't just print them using the println console or anything we have; instead, we send messages to the logging framework, which handles the console or any other logging destination, such as files. The beauty of this framework is that we don't need to delete logs after debugging is complete-- we just need to configure the framework to suppress all debug-level messages in a production environment. Some logging records may occur in unit tests, do we also leave them or not?

This is an example (it simplifies the real unit test from Polystat in CalcTest.java, which is the static analyzer we are currently working on):

Import com.jcabi.log.Logger;import com.jcabi.xml.XML;import org.hamcrest.MatcherAssert;import org.hamcrest.Matchers;import org.junit.jupiter.api.Test;public final class FooTest {@ Test public void buildsSimpleXml () {final XML xml = new Foo (). Build (); Logger.debug (this, "This is the XML:\ n% s", xml.toString ()); MatcherAssert.assertThat (xml, Matchers.notNullValue ());}}

This is Java, and I use JUnit5 + Hamcrest with my own logging framework, jcabi-log, which is a decorator for Slf4j and prints to the console using Log4j.

What's going on here? There is a class build () of Foo with a method, which generates an XML document (I'm using the jcabi-xml library, which is the decorator of JDK DOM). Then, the unit test prints the contents of the XML document to the console and makes a very stupid assertion: the document is not NULL. This is stupid because if it is NULL, the log statement will fail when .toString () is called.

I'm the developer of this code, so I know what happened: I didn't bother to write a correct assertion, which looked at the XML document and made sure there were the right elements in it. I just print it to the console, visually confirm its validity and call it one day. If I had more time, this would be how I write better unit tests (I just improved Polystat tests):

Import com.jcabi.matchers.XhtmlMatchers;import org.hamcrest.MatcherAssert;import org.junit.jupiter.api.Test;public final class FooTest {@ Test public void buildsSimpleXml () {MatcherAssert.assertThat (XhtmlMatchers.xhtml (new Foo (). Build ()), XhtmlMatchers.hasXPath ("/ / foo");}}

Now you have built the XML document and tested it for the existence of / / foo XPath. The contents of the document are printed to the console only if the assertion fails. If XML has the required XPath, there will be no console output, which means no noise for future developers.

In addition, it is now a single-statement test, which in itself is a good practice.

Reviewing my experience of testing and documenting, I think recording unit tests is a bad idea. Sometimes it's inevitable because we're lazy or don't have enough time at all, but it's still bad. Logging helps us visually confirm the correctness of the output, but it takes that knowledge away from the project. Those who will test later will not know what we saw there. They will see the output on the console, but they don't know if it still meets my expectations at the time of writing this article.

I would say that every logging line in a unit test is a message from its author: "I know something about the data I'm seeing now, but I'm too lazy to tell you that you just have to trust me."

I suggest that we don't leave such a message in our code.

At this point, I believe you have a deeper understanding of "Java login unit test case analysis". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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