index.js

export function isStream(stream, {checkOpen = true} = {}) {
	return stream !== null
		&& typeof stream === 'object'
		&& (stream.writable || stream.readable || !checkOpen || (stream.writable === undefined && stream.readable === undefined))
		&& typeof stream.pipe === 'function';
}

export function isWritableStream(stream, {checkOpen = true} = {}) {
	return isStream(stream, {checkOpen})
		&& (stream.writable || !checkOpen)
		&& typeof stream.write === 'function'
		&& typeof stream.end === 'function'
		&& typeof stream.writable === 'boolean'
		&& typeof stream.writableObjectMode === 'boolean'
		&& typeof stream.destroy === 'function'
		&& typeof stream.destroyed === 'boolean';
}

export function isReadableStream(stream, {checkOpen = true} = {}) {
	return isStream(stream, {checkOpen})
		&& (stream.readable || !checkOpen)
		&& typeof stream.read === 'function'
		&& typeof stream.readable === 'boolean'
		&& typeof stream.readableObjectMode === 'boolean'
		&& typeof stream.destroy === 'function'
		&& typeof stream.destroyed === 'boolean';
}

export function isDuplexStream(stream, options) {
	return isWritableStream(stream, options)
		&& isReadableStream(stream, options);
}

export function isTransformStream(stream, options) {
	return isDuplexStream(stream, options)
		&& typeof stream._transform === 'function';
}