---
title: "**echo**(1) acceptance tests"
...
# Introduction
**echo**(1) is a Unix command line tool, which writes
its command line arguments to the standard output.
This is a simple acceptance test suite for the
`/bin/echo` implementation.

# No arguments
Run `/bin/echo` without arguments.
```fable
when user runs echo without arguments
then exit code is 0
and standard output contains a newline
and standard error is empty
```