System.out.print() doesn't show anything in test methods

Question

I\'m trying to print some data with System.out in my unit tests (@Test mehotds), but it is not showing anything. However, it works properly in

Answer 1

Ran into this as well. I'm using gradle to manage my tasks and I put this in at the end of by build.gradle file :

test {
  testLogging.showStandardStreams = true
}

Now I see System.out.println(whateves).

Answer 2

The -Dtest=* command line option of Maven appears to trigger the show of stdout in unit tests.

By convention, the stdout shows in target/surefire-reports/*-output.txt. Apparently, the Surefire plugin developers could not reuse stdout for communication of many things between the tests and the framework.

Answer 3

I made i little trick in separate non-test class. It is not that smooth as logger, but if you are looking for quick solution in Spring Boot you can use this.

PrintForTest.java

import org.springframework.stereotype.Controller;

@Controller
public class PrintForTest {

    public static void print(String input){
        System.out.println(input);
    }
}

MainTest.java

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.junit.Assert;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

@SpringBootTest
@RunWith(SpringRunner.class)
public class MainTest {

...

    @Test
    public void testingSomething(){
        PrintForTest.print("My new System.out.print()");
        Assert.assertEquals(...);
    }
}

---

edited: using static method, no need to use @Autowired.

Answer 4

To get the output of your written Tests via System.out.println you need to configure maven-surefire-plugin to redirect this output into a file which can be achieved by using the following:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-surefire-plugin</artifactId>
  <version>2.18.1</version>
  <configuration>
    <redirectTestOutputToFile>true</redirectTestOutputToFile>
  </configuration>
</plugin>

The option redirectTestOutputToFile will redirect the output of System.out.println etc. into a file which is separately created:

Excerpt from the docs:

Set this to "true" to redirect the unit test standard output to a file (found in reportsDirectory/testName-output.txt).

Apart from that a System.out.println does not make sense in a unit test in general.

Answer 5

The problem is the name of your test class. To be recognized in the test phase within the build (by the Maven surefire plugin), it must be named "*Test":

Inclusions and Exclusions of Tests

Answer 6

I am using gradle. I had this problem with both System.out and java.util.logging.Logger. I edited the following part of my build.gradle file:

test {
  testLogging {
    exceptionFormat = 'full'
    events = ["passed", "failed", "skipped"]
  }
}

and added showStandardStreams = true under testLogging. The result was as follows:

test {
  testLogging {
    exceptionFormat = 'full'
    events = ["passed", "failed", "skipped"]
    showStandardStreams = true
  }
}

It fixed both of them.