Why Does System.out.print() Not Display Output in JUnit Test Methods?

Why isn't System.out.print() working in my JUnit test methods?

public class MyTests {

  @Before
  void init(){
    System.out.println("Initializing some data..."); // Works as expected
  }

  @Test
  void shouldRemoveSeries() {
    System.out.println("TEST: Should remove series"); // No output here
  }
}

When using JUnit with the Maven Surefire plugin, output from System.out.println() statements in your test methods may not display as expected. This can occur due to how the test framework manages output streams during test execution.

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-surefire-plugin</artifactId>
  <version>2.22.2</version>
  <configuration>
    <redirectTestOutputToFile>true</redirectTestOutputToFile>
    <includes>
      <include>**/*Tests.java</include>
    </includes>
  </configuration>
</plugin>

Causes

• The Maven Surefire plugin buffers output during test runs, which may prevent immediate display.
• JUnit outputs logs to a different stream that might not be visible in the console unless configured.

Solutions

• Use Logger instead of System.out for better tracking of test outputs.
• Update the Maven Surefire plugin to the latest version to ensure optimal output handling.
• Configure Maven Surefire plugin to not buffer output; you can set the `redirectTestOutputToFile` property to `true`.
• Run your tests using the command line, where output may display more reliably.

Mistake: Not updating the Maven Surefire plugin version.

Solution: Ensure you use the latest version of the plugin for improved functionality.

Mistake: Using System.out.println() instead of a logging framework.

Solution: Switch to using a logging framework like SLF4J or Log4j for better output management.

Mistake: Ignoring test output configuration settings in Maven.

Solution: Check your pom.xml for any output redirection or buffering settings.