Built-in commands not available for 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.