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+# Bats: the Bash Automated Testing System
+
+Bats is a [TAP](http://testanything.org/)-compliant testing framework
+for Bash. It provides a simple way to verify that the UNIX programs
+you write behave as expected.
+
+A Bats test file is a Bash script with special syntax for defining
+test cases. Under the hood, each test case is just a function with a
+description.
+
+```bash
+#!/usr/bin/env bats
+
+@test "addition using bc" {
+  result="$(echo 2+2 | bc)"
+  [ "$result" -eq 4 ]
+}
+
+@test "addition using dc" {
+  result="$(echo 2 2+p | dc)"
+  [ "$result" -eq 4 ]
+}
+```
+
+Test cases consist of standard shell commands. Bats makes use of
+Bash's `errexit` (`set -e`) option when running test cases. If every
+command in the test case exits with a `0` status code (success), the
+test passes. In this way, each line is an assertion of truth.
+
+To run your tests, invoke the `bats` interpreter with a path to a test
+file. The file's test cases are run sequentially and in isolation, and
+the results are written to standard output in human-readable TAP
+format. If all the test cases pass, `bats` exits with a `0` status
+code. If there is a failure, `bats` exits with a `1` status code.
+
+    $ bats addition.bats
+    1..2
+    ok 1 addition using bc
+    ok 2 addition using dc
+    $ echo $?
+    0
+
+You can also define special `setup` and `teardown` functions which run
+before and after each test case, respectively. Use these to load
+fixtures, set up your environment, and clean up when you're done.
+
+Bats is most useful when testing software written in Bash, but you can
+use it to test any UNIX program.