anchor.diff:  
       String expected = String.format("" +
               "Usage: <main class> [--option=<option>]%n" +
  -            "      --option=<option>   Some options. Default: some-value%n");
  +            "      --option=<option>   Some option. Default: some-value%n");
       assertEquals(expected, actual);
   }
   ----
   
  -
  -==== JUnit 4 with `EnvironmentVariables`
  -Applications that use JUnit 4 can use Stephan Birkner's https://stefanbirkner.github.io/system-rules[System-Rules] project for https://stefanbirkner.github.io/system-rules/#EnvironmentVariables[testing environment variables].
  -
  -[source,java]
  +.Java/JUnit 4
  +[source,java,role=secondary]
   ----
   import org.junit.contrib.java.lang.system.EnvironmentVariables;
   // ...
  
positive.code:         environmentVariables.set("OTHER_VAR", "second value");
  
          String actual = new CommandLine(new MyApp())
                  .getUsageMessage(CommandLine.Help.Ansi.OFF));
  
          String expected = String.format("" +
                  "Usage: <main class> [--option=<option>]%n" +
                  "      --option=<option>   Some options. Default: some-value%n");
          assertEquals(expected, actual);
      }
  }
  ----
  
  
negative.code: === Testing Environment Variables
  
  Since picocli offers support for using <<Variable Interpolation,environment variables>> in the annotations, you may want to test this.
  Depending on your programming language, your environment and your testing framework, you have several options: 
  
  * **Java 8**: You can use Stephan Birkner's https://github.com/stefanbirkner/system-lambda[System-Lambda] project for testing https://github.com/stefanbirkner/system-lambda#environment-variables[environment variables]
  
  * **Java + Junit 4**: You can use Stephan Birkner's https://stefanbirkner.github.io/system-rules[System-Rules] project for testing the https://stefanbirkner.github.io/system-rules/#EnvironmentVariables[environment variables].
  * **Kotlin + Kotest**: Kotlin coders you may use the https://kotest.io/[Kotest] test framework which comes with https://kotest.io/docs/extensions/system_extensions.html#system-environment[System Environment] extension that allow you to test environment variables.
  
  The listing below provides code samples for the three options mentioned above:
  
  .Java 8
  [source,java,role=primary]
  ----
  import static com.github.stefanbirkner.systemlambda.SystemLambda.withEnvironmentVariable;
  // ...
  