junit-team/junit5 · error · ParameterException

${e.getMessage()}

Error message

${e.getMessage()}

What it means

This is a wrapper exception thrown by the picocli-based console launcher's BaseCommand.call() when a subcommand's execute() method throws a PreconditionViolationException. It converts the violation into a picocli ParameterException so the CLI can render usage help and a proper exit code rather than dumping a raw stack trace. The message content comes from the original precondition violation (e.getMessage()).

Source

Thrown at junit-platform-console/src/main/java/org/junit/platform/console/command/BaseCommand.java:85

					commandLine.getErr().flush();
					cmd.usage(commandLine.getOut());
					return ExitCode.ANY_ERROR;
				}) //
				.setCaseInsensitiveEnumValuesAllowed(true) //
				.setAtFileCommentChar(null);
	}

	@Override
	public final T call() {
		PrintWriter out = getOut();
		if (!disableBanner) {
			displayBanner(out);
		}
		try {
			return execute(out);
		}
		catch (PreconditionViolationException e) {
			throw new ParameterException(commandSpec.commandLine(), e.getMessage(), e.getCause());
		}
	}

	private PrintWriter getOut() {
		return commandSpec.commandLine().getOut();
	}

	private void displayBanner(PrintWriter out) {
		out.println();
		CommandLine.Help.ColorScheme colorScheme = getColorScheme();
		if (colorScheme.ansi().enabled()) {
			out.print("💚 ");
		}
		out.println(colorScheme.string(
			"@|italic Thanks for using JUnit!|@ Support its development at @|underline https://junit.org/sponsoring|@"));
		out.println();
		out.flush();
	}

View on GitHub (pinned to f070c699a0)

Solutions

1. Read the full error message: it is the downstream precondition text (e.getMessage()), which identifies which argument/selector is at fault — fix that argument.
2. Re-run with --help on the specific subcommand (e.g. 'junit execute --help' or 'junit discover --help') to confirm accepted options and value formats.
3. If the underlying cause chain is unclear, temporarily remove --disable-banner is not relevant; instead enable picocli's stack trace by inspecting the printed usage, or run a tiny Launcher API call to reproduce the precondition outside the CLI.
4. Ensure the junit-platform-console and junit-platform-launcher versions are aligned (see error 112) so preconditions are not misreported.

Example fix

// before
java -jar junit-platform-console-standalone.jar execute --select 'bad spec' --config=''
// after: provide a valid selector and config value
java -jar junit-platform-console-standalone.jar execute --select-class com.example.MyTests --config 'junit.jupiter.testinstance.lifecycle.default=per_class'

// Validate selector strings before invoking the launcher programmatically.
// For the CLI case, validate args at the script level:
if (args.length == 0 || (!args[0].equals("discover") && !args[0].equals("execute"))) {
  System.err.println("First arg must be 'discover' or 'execute' (or use --help/--version).");
  System.exit(2);
}

// When embedding the launcher, catch PreconditionViolationException before it is wrapped.
try {
  LauncherFactory.create().execute(request);
} catch (org.junit.platform.commons.PreconditionViolationException e) {
  // handle invalid request construction
  throw new IllegalArgumentException("Bad launcher request: " + e.getMessage(), e);
}

When it happens

Trigger: Running the JUnit Platform Console Launcher (junit-platform-console[-standalone]) with invalid arguments that pass picocli parsing but fail a programmatic precondition inside a subcommand's execute() — e.g. mutually-exclusive options, a selector that cannot be resolved, or an invalid configuration parameter value. Any PreconditionViolationException raised downstream during discover/execute lands here.

Common situations: Invoking the standalone jar with a malformed --select, --scan-classpath with no matching classpath entries, passing --config KEY=VALUE with an invalid value, or combining options the subcommand later rejects. Common when scripting the console launcher in CI or from build tools.

Related errors

• Missing required subcommand
• Duplicate key '%s' for values '%s' and '%s'.
• Unsupported argument count validation mode: %s
• Invalid classpath entry: ${path}
• Failed to close custom class loader

AI-assisted analysis of junit-team/junit5@f070c699a0 (2026-08-11). Data as JSON: /api/errors/165eea15ff4f100d. Report an issue: GitHub.