bats(7) -- Bats test file format
================================


DESCRIPTION
-----------

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.

    #!/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 ]
    }


Each Bats test file is evaluated n+1 times, where _n_ is the number of
test cases in the file. The first run counts the number of test cases,
then iterates over the test cases and executes each one in its own
process.


THE RUN HELPER
--------------

Many Bats tests need to run a command and then make assertions about
its exit status and output. Bats includes a `run` helper that invokes
its arguments as a command, saves the exit status and output into
special global variables, and then returns with a `0` status code so
you can continue to make assertions in your test case.

For example, let's say you're testing that the `foo` command, when
passed a nonexistent filename, exits with a `1` status code and prints
an error message.

    @test "invoking foo with a nonexistent file prints an error" {
      run foo nonexistent_filename
      [ "$status" -eq 1 ]
      [ "$output" = "foo: no such file 'nonexistent_filename'" ]
    }

The `$status` variable contains the status code of the command, and
the `$output` variable contains the combined contents of the command's
standard output and standard error streams.

A third special variable, the `$lines` array, is available for easily
accessing individual lines of output. For example, if you want to test
that invoking `foo` without any arguments prints usage information on
the first line:

    @test "invoking foo without arguments prints usage" {
      run foo
      [ "$status" -eq 1 ]
      [ "${lines[0]}" = "usage: foo <filename>" ]
    }


THE LOAD COMMAND
----------------

You may want to share common code across multiple test files. Bats
includes a convenient `load` command for sourcing a Bash source file
relative to the location of the current test file. For example, if you
have a Bats test in `test/foo.bats`, the command

    load test_helper

will source the script `test/test_helper.bash` in your test file. This
can be useful for sharing functions to set up your environment or load
fixtures.


THE SKIP COMMAND
----------------

Tests can be skipped by using the `skip` command at the point in a
test you wish to skip.

    @test "A test I don't want to execute for now" {
      skip
      run foo
      [ "$status" -eq 0 ]
    }

Optionally, you may include a reason for skipping:

    @test "A test I don't want to execute for now" {
      skip "This command will return zero soon, but not now"
      run foo
      [ "$status" -eq 0 ]
    }

Or you can skip conditionally:

    @test "A test which should run" {
      if [ foo != bar ]; then
        skip "foo isn't bar"
      fi

      run foo
      [ "$status" -eq 0 ]
    }


THE TODO COMMAND
----------------

Tests can be marked as TODO by using the `todo` command at the point in a test before it completes.

A passing test marked with TODO should be considered a "bonus", but both pass and fail are considered successful.

See [the TAP specification](http://testanything.org/tap-specification.html) for more details on this feature.

    @test "A test that may fail" {
      todo
      run foo
      [ "$status" -eq 0 ]
    }

Optionally, you may include a reason for marking TODO:

    @test "A test that may fail" {
      todo "This command will return zero soon, but not now"
      run foo
      [ "$status" -eq 0 ]
    }

Or you can mark todo conditionally:

    @test "A test which usually fails on a mac" {
      if [ $(uname -s) == Darwin ]; then
        todo "Get this working on a Mac"
      fi

      run foo
      [ "$status" -eq 0 ]
    }


SETUP AND TEARDOWN FUNCTIONS
----------------------------

You can 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.


CODE OUTSIDE OF TEST CASES
--------------------------

You can include code in your test file outside of `@test` functions.
For example, this may be useful if you want to check for dependencies
and fail immediately if they're not present. However, any output that
you print in code outside of `@test`, `setup` or `teardown` functions
must be redirected to `stderr` (`>&2`). Otherwise, the output may
cause Bats to fail by polluting the TAP stream on `stdout`.


SPECIAL VARIABLES
-----------------

There are several global variables you can use to introspect on Bats
tests:

* `$BATS_TEST_FILENAME` is the fully expanded path to the Bats test
file.
* `$BATS_TEST_DIRNAME` is the directory in which the Bats test file is
located.
* `$BATS_TEST_NAMES` is an array of function names for each test case.
* `$BATS_TEST_NAME` is the name of the function containing the current
test case.
* `$BATS_TEST_DESCRIPTION` is the description of the current test
case.
* `$BATS_TEST_NUMBER` is the (1-based) index of the current test case
in the test file.
* `$BATS_TMPDIR` is the location to a directory that may be used to
store temporary files.


SEE ALSO
--------

`bash`(1), `bats`(1)