Command output not available in non-interactive mode in 4.0

[ThomasVitale]

In Spring Shell 4.0, the built-in commands don't seem to be available when running in non-interactive mode (e.g. help or version). They don't work for showing the available command (e.g. mycli help) and don't work for subcommands either (e.g. mycli cmd --help).

The curious thing is that the built-in commands/options seem to be registered internally in Spring Shell, so no error is thrown when calling them. However, the output is always empty.

I'm available to help with a potential PR.

[czpilar]

They are available; however, they are printed to PrintWriter.nullWriter() because the non-interactive shell runner uses it by default.

spring-shell/spring-shell-core/src/main/java/org/springframework/shell/core/NonInteractiveShellRunner.java

Line 52 in 2a1f020

private final PrintWriter outputWriter = new PrintWriter(PrintWriter.nullWriter());

[czpilar]

It will be possible to reconfigure the non-interactive shell runner to use System.out as its PrintWriter after my PR (#1275) is merged, for example like this:

@Primary
@Bean
@ConditionalOnProperty(prefix = "spring.shell.interactive", name = "enabled", havingValue = "false")
public ShellRunner sysOutNonInteractiveShellRunner(CommandParser commandParser, CommandRegistry commandRegistry) {
	return new NonInteractiveShellRunner(commandParser, commandRegistry, new PrintWriter(System.out));
}

Or it might be a good idea to have a PrintWriter defined as a bean and inject it into the non-interactive shell runner. However, this would be a design change that I cannot make myself. Only maintainer can.

[fmbenhassine]

@ThomasVitale Thank you for reporting this issue.

The curious thing is that the built-in commands/options seem to be registered internally in Spring Shell, so no error is thrown when calling them. However, the output is always empty.

Indeed, they are available, but the output writer was incorrectly set to discard everything in non-interactive mode. I planned the fix for the upcoming 4.0.1.

Thank you for the follow up, @czpilar!

[ThomasVitale]

Thanks so much @fmbenhassine and @czpilar!