Testing

A program's input and output can all be injected, so a CLI can be tested in-process without spawning Node or touching process:

• run(argv) takes argv directly
• stdout and stderr receive output
• exit receives the exit code instead of setting process.exitCode
• env replaces process.env for flags' environment variables

import { arg, command, jinju } from 'jinju';
import { expect, test } from 'vitest';

const greet = command({
	description: 'Greet someone',
	args: [arg.string({ name: 'name', description: 'Who to greet' }).required()],
	run: ({ args: [name] }) => {
		console.log(`Hello, ${name}!`);
	},
});

const setup = () => {
	const output = { stdout: '', stderr: '' };
	const app = jinju({
		name: 'greet',
		commands: { $: greet },
		env: {},
		stdout: (text) => (output.stdout += text),
		stderr: (text) => (output.stderr += text),
		exit: () => {},
	});
	return { app, output };
};

test('requires a name', async () => {
	const { app, output } = setup();

	expect(await app.run([])).toBe(1);
	expect(output.stderr).toContain('Missing required argument <name>');
});

stdout only receives Jinju's own output (help and version). Output your run handlers write is up to you. For testable handlers, pass dependencies such as a logger in from the outside.

Testing commands directly

A command's parse(argv, options?) method parses input without a program, and resolves to { ok: true, value } or { ok: false, errors }:

const serve = command({
	description: 'Serve',
	flags: { port: flag.number({ description: 'Port' }).default(8080) },
	run: () => {},
});

const result = await serve.parse(['--port', '3000']);
if (result.ok) result.value.flags; // { port: 3000 }

Snapshotting help

app.help(path?) returns a help page as a string, which is handy for snapshot tests:

expect(app.help(['sync'])).toMatchSnapshot();