354 lines
10 KiB
ReStructuredText
354 lines
10 KiB
ReStructuredText
.. index:: BATS
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************************************
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BATS - Bash Automated Testing System
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************************************
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The CoreOS distribution supports writing tests using shell syntax by providing the `bats` command.
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If you want to use `bats`, you will need the following CoreOS packages:
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- bats
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- bats-file
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- bats-assert
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Overview of BATS
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================
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A BATS test can be as simple as a single .bats file. For example:
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.. code-block:: bash
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#!/usr/bin/env bats
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bats_load_library bats-support
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bats_load_library bats-assert
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@test "can output to stdout" {
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run echo hello
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assert_output 'hello'
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}
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You can run it using the command `bats <filename>.bats`
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This will give you the following output:
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.. code-block:: bash
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sam@SAVE:~/Projects/tests$ bats <filename>.bats
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<filename>.bats
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✓ can output to stdout
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1 test, 0 failures
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The run command
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================
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In shell tests, you often need to run commands and capture their output, exit
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status, and error messages. The run command provided by `bats` allows you to
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execute commands within your test cases and collect this information for later
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assertion and validation.
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The run command will make the following variables available:
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- `${status}`: exit code of the command run by `run`
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- `${output}`: combined content of `stdout` and `stderr`
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- `${lines[@]}`: array of lines of the output
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- `${BATS_RUN_COMMAND}`: command run by the `run` command
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.. code-block:: bash
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@test "invoking foo with a nonexistent file prints an error" {
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run foo nonexistent_filename
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[ "$status" -eq 1 ]
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[ "$output" = "foo: no such file 'nonexistent_filename'" ]
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[ "$BATS_RUN_COMMAND" = "foo nonexistent_filename" ]
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}
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The `run` command accepts some parameters:
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- `-N`: Expect N as exit status and fail otherwise
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- `-!`: Expect non-zero exit status and fail if the command succeeds.
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- `--keep-empty-lines`: don't remove empty lines from `${lines}`
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- `--separate-stderr`: Use separate variables for stderr `${stderr}` and `${stderr_lines[@]}`
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.. code-block:: bash
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@test "invoking foo without arguments prints usage" {
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run -1 foo
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[ "${lines[0]}" = "usage: foo <filename>" ]
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}
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The bats-assert helper
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======================
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The `bats-assert` helper provides some functions to create more readable tests.
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These assertions use the variables created by the `run` command and can be used
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as follows:
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.. code-block:: bash
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@test 'assert_output()' {
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run echo 'have'
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assert_output 'want'
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}
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The following functions are provided:
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- `assert` and `refute`: Assert that a given expression evaluates to true or false.
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- `assert_equal`: Assert that two parameters are equal.
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- `assert_not_equal`: Assert that two parameters are not equal.
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- `assert_success` and `assert_failure`: Assert that the exit status is 0 or 1.
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- `assert_output` and `refute_output`: Assert that the output does (or does not) contain the given content.
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- `assert_line` and `refute_line`: Assert that a specific line of the output does (or does not) contain the given content.
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- `assert_regex` and `refute_regex`: Assert that a parameter matches (or does not match) the given pattern.
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The bats-file helper
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====================
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The `bats-file` helper provides functions to help work with files in tests:
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**Test File Types:**
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- `assert_exists` and `assert_not_exists`: Check if a file or directory exists.
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- `assert_file_exists` and `assert_file_not_exists`: Check if a file exists.
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- `assert_dir_exists` and `assert_dir_not_exists`: Check if a directory exists.
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- `assert_link_exists` and `assert_link_not_exists`: Check if a link exists.
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- `assert_block_exists` and `assert_block_not_exists`: Check if a block special file exists.
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- `assert_character_exists` and `assert_character_not_exists`: Check if a character special file exists.
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- `assert_socket_exists` and `assert_socket_not_exists`: Check if a socket exists.
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- `assert_fifo_exists` and `assert_fifo_not_exists`: Check if a fifo special file exists.
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**Test File Attributes:**
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- `assert_file_executable` and `assert_file_not_executable`
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- `assert_file_owner` and `assert_file_not_owner`
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- `assert_file_permission` and `assert_not_file_permission`
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- `assert_file_size_equals`
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- `assert_size_zero` and `assert_size_not_zero`
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- `assert_file_group_id_set` and `assert_file_not_group_id_set`
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- `assert_file_user_id_set` and `assert_file_not_user_id_set`
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- `assert_sticky_bit` and `assert_no_sticky_bit`
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**Test File Content:**
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- `assert_file_empty` and `assert_file_not_empty`
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- `assert_file_contains` and `assert_file_not_contains`
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- `assert_symlink_to` and `assert_not_symlink_to`
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**Working with a temporary directory:**
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- `temp_make` and `temp_del`
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Pre- and Post-test case hooks
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==============================
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In some cases, it's useful to have a function that runs before or after each test
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case in a bats file.
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A function named `setup` will run before each test case, and a function
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named `teardown` will run after each test case.
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This example creates a directory in the setup function but lacks a teardown
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that removes the directory. The second time the setup function is run, the
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setup will fail as the directory already exists:
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.. code-block:: bash
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#!/usr/bin/env bats
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bats_load_library bats-support
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bats_load_library bats-assert
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bats_load_library bats-file
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setup() {
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mkdir tmp
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echo 'a' >> ./tmp/test
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}
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@test "test contains a single a I" {
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assert_file_contains ./tmp/test '^a$'
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}
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@test "test contains a single a II" {
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assert_file_contains ./tmp/test '^a$'
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}
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.. code-block:: bash
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sam@SAVE:~/Projects/tests$ bats test.bats
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test.bats
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✓ test contains a single a I
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✗ test contains a single a II
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(from function `setup' in test file test.bats, line 8)
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`mkdir tmp' failed
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mkdir: cannot create directory ‘tmp’: File exists
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2 tests, 1 failure
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This can be easily fixed by adding a teardown function:
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.. code-block:: bash
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#!/usr/bin/env bats
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bats_load_library bats-support
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bats_load_library bats-assert
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bats_load_library bats-file
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setup() {
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mkdir tmp
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echo 'a' >> ./tmp/test
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}
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teardown() {
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rm -rf ./tmp
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}
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@test "test contains a single a I" {
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assert_file_contains ./tmp/test '^a$'
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}
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@test "test contains a single a II" {
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assert_file_contains ./tmp/test '^a$'
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}
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.. code-block:: bash
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sam@SAVE:~/Projects/tests$ bats test.bats
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test.bats
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✓ test contains a single a I
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✓ test contains a single a II
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2 tests, 0 failures
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Pre- and Post-test file hooks
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=============================
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To run some code before executing a test file or after executing it, the
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functions `setup_file` and `teardown_file` can be used.
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The last example could be refactored to only create the tmp directory once:
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.. code-block:: bash
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#!/usr/bin/env bats
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bats_load_library bats-support
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bats_load_library bats-assert
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bats_load_library bats-file
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setup_file() {
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export DIR="./tmp"
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export FILE="${DIR}/test"
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mkdir "${DIR}"
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}
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teardown_file() {
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rm -rf "${DIR}"
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}
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setup() {
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echo 'a' >> "${FILE}"
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}
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teardown() {
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rm "${FILE}"
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}
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@test "test contains a single a I" {
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assert_file_contains "${FILE}" '^a$'
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}
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@test "test contains a single a II" {
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assert_file_contains "${FILE}" '^a$'
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}
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Multiple files
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==============
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With `bats`, a file is a test suite. If you have multiple `bats` files in a
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directory and you provide the directory in the `bats` command line, `bats`
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will execute all the test suites.
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Example: `bats .`
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.. code-block:: bash
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sam@SAVE:~/Projects/tests$ bats .
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./first.bats
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✓ can run our script
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✗ second test
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(in test file ./first.bats, line 27)
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`false' failed
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./second.bats
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✓ multi file
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./test.bats
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✓ test contains a single a I
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✓ test contains a single a II
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5 tests, 1 failure
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Pre- and Post-suite hooks
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=========================
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If you want to execute the same function before each test suite or after
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each test suite, create a file named `setup_suite.bash`. In this file,
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create a function named `setup_suite()` and another named `teardown_suite()`.
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Exporting the test results
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==========================
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Test results can be exported using the JUnit XML format. This can then be
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used in other tools and merged with other JUnit XML formats to generate a final
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test report.
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Example:
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.. code-block:: bash
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sam@SAVE:~/Projects/tests$ bats . -F junit
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This will produce the following XML content on stdout:
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.. code-block:: xml
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<?xml version="1.0" encoding="UTF-8"?>
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<testsuites time="0.048">
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<testsuite name="./first.bats" tests="2" failures="1" errors="0" skipped="0" time="0.025" timestamp="2023-08-16T14:22:15" hostname="SAVE">
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<testcase classname="./first.bats" name="can run our script" time="0.013" />
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<testcase classname="./first.bats" name="second test" time="0.012">
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<failure type="failure">(in test file ./first.bats, line 27)
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`false' failed</failure>
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</testcase>
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</testsuite>
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<testsuite name="./second.bats" tests="1" failures="0" errors="0" skipped="0" time="0.008" timestamp="2023-08-16T14:22:15" hostname="SAVE">
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<testcase classname="./second.bats" name="multi file" time="0.008" />
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</testsuite>
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<testsuite name="./test.bats" tests="2" failures="0" errors="0" skipped="0" time="0.015" timestamp="2023-08-16T14:22:15" hostname="SAVE">
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<testcase classname="./test.bats" name="test contains a single a I" time="0.008" />
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<testcase classname="./test.bats" name="test contains a single a II" time="0.007" />
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</testsuite>
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</testsuites>
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Going further
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=============
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`bats` scripts can be checked with shellcheck for common mistakes.
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The `bats-assert` add-on provides many helper functions to perform
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assertions with a more readable syntax than the shell's built-in syntax.
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See https://github.com/bats-core/bats-assert
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The `bats-file` add-on provides helper functions to check for files. See
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https://github.com/bats-core/bats-file/
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You can find a list of projects using `bats` on this page:
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https://github.com/bats-core/bats-core/wiki/Projects-Using-Bats |