Cmdtest User Guide
==================

.. contents::

Introduction
------------

Cmdtest is a `unit testing`_ framework for testing commands (executable programs).
In other test frameworks the "unit" tested is often a class (e.g. in Java's JUnit_ or
Ruby's `Test::Unit`_), but in Cmdtest the unit is an executable. Apart from this
difference Cmdtest borrows many ideas from the other frameworks.
The program ``cmdtest`` runs the tests and reports the success or failure
in different ways, e.g. by writing to standard output or producing an XML-file on
Ant/JUnit format. The testcases are written in Ruby code. Assertions can
be made about the side effects performed by a command:

- the exit status

- the content of standard output

- the content of standard error

- newly created/removed/changed files, or other changes to the
  filesystem

A simple example
----------------

::

  $ cat CMDTEST_example.rb
  class CMDTEST_example < Cmdtest::Testcase

    def test_misc
      cmd "echo hello world" do
        stdout_equal "hello world\n"
      end

      cmd "touch foo.txt ; exit 7" do
        created_files "foo.txt"
        exit_status 7
      end
    end

  end

This example shows the basic structure of a testcase file. First we make a
subclass of ``Cmdtest::Testcase``. All methods of the new class with a
name like ``test_*`` will be considered testcases.
Inside a method we can call the ``cmd`` method. It will
execute the command given as argument and then check the assertions
given in the do-block. When ``cmdtest`` is run, it will find all
``CMDTEST_*.rb`` files in the current directory and run the tests in
the files. The output looks like::

  $ cmdtest
  ### ======================================== CMDTEST_example.rb
  ### echo hello world
  ### touch foo.txt ; exit 7

  ### 1 test classes, 1 test methods, 2 commands, 0 errors.

If we change "7" to "8", "foo" to "bar" and "world" to "WORLD" in
the example, we get the following errors::

  $ cmdtest
  ### ======================================== CMDTEST_example.rb
  ### echo hello WORLD
  --- ERROR: wrong stdout
  ---        actual: hello WORLD
  ---        expect: hello world
  ### touch bar.txt ; exit 8
  --- ERROR: created files
  ---        actual: ["bar.txt"]
  ---        expect: ["foo.txt"]
  --- ERROR: expected 7 exit status, got 8

  --- 1 test classes, 1 test methods, 2 commands, 2 errors.

The following sections will describe in more detail what can be done
with Cmdtest. See also the ``examples`` directory of the Cmdtest project,
where some larger examples of Cmdtest usage can be found.

Reporting format
----------------

Normally Cmdtest writes lines on standard output to show the progress of the
testing. As long as no error occurs, the lines will be prefixed by
"###". Error messages will instead have a "---" prefix. This makes it easy
to spot errors just by looking in the left margin. Each call to ``cmd``
will give one line on standard output. Normally the command executed will be
shown (after the "###" prefix). But one can also replace the string
written by calling the ``comment`` method inside the do-block of a ``cmd``
call.

When an error occurs in a test-method, the rest of the method will be
skipped. But all errors occurring at the same command will be reported.

Cmdtest can also be directed to write an XML file on the same format as
that used by Ant/JUnit. This makes it possible to use Cmdtest together
with `continuous integration`_ servers like Hudson_.

Structure of a test-file
------------------------

Each test-file can contain one or more subclasses to
``Cmdtest::Testcase``. The methods that are special are:

``test_*``
  These are the methods that will run tests.
  For each method, a newly created object of the class will be used.

``setup``
  This method is called before each ``test_*`` method is called.
  It gives the user a chance to initialize the "environment" of all
  the ``test_*`` methods of the class. It can be seen as a "user level"
  constructor.

``teardown``
  This method is called after each ``test_*`` method was called.  It
  gives the user a chance to cleanup the "environment" of all the
  ``test_*`` methods of the class, e.g. release some resource acquired
  by the ``setup`` method. It can be seen as a "user level" destructor.

Structure of a test-method
--------------------------

Each test-method (named ``test_*``) should contain a number of calls to
the ``cmd`` method. Inside the do-block of the ``cmd`` calls, a number of
assertions can be made about the outcome of the command. The simplest
possible call looks like::

  cmd "true" do
  end

Here no explicit assertions have been given. In that case Cmdtest
applies some implicit assertions. The code above is equivalent to the
following more explicit one::

  cmd "true" do
    exit_zero
    stdout_equal ""
    stderr_equal ""
    created_files []
    modified_files []
    removed_files []
  end

The idea is that all differences in behaviour from the trivial ``true``
command should be described as an assertion in the do-block. The list
of possible assertions includes: ``exit_zero``, ``exit_nonzero``,
``exit_status``, ``created_files``, ``modified_files``, ``removed_files``,
``written_files``, ``affected_files``, ``file_equal``, ``stdout_equal``
and ``stderr_equal``.

In addition to the assertions there are other helper-functions to set
up the "environment" for the commands and assertions. An example is
the creation of files::

  ...
  create_file "foo.txt", "abc\ndef\n"
  cmd "cat -n foo.txt" do
    stdout_equal [
      "     1\tabc",
      "     2\tdef",
    ]
  end
  ...

The list of such helper functions includes:
``create_file``, ``touch_file``, ``import_file`` and ``ignore_file``.
Beside these methods the test can of course also contain arbitrary Ruby-code.


Work directory
--------------

All tests are performed in a "clean" temporary directory, here called the "work directory".
When the ``setup``, ``test_*`` and ``teardown`` methods are called the current directory
will be the "work directory" (unless ``Dir.chdir`` is called by the methods themselves).

Several of the assertions and helper functions take filename arguments
that are evaluated relative to the "work directory" (or sometimes the
current directory if they differ).

Matching standard output content
--------------------------------

An assertion like ``stdout_equal`` compares the actual standard output of a
command with the expected outcome. The expected value can be specified
in different ways, and is best explained by example::

  cmd "echo hello ; echo world" do
    stdout_equal "hello\nworld\n"            # 1
    stdout_equal [                           # 2
      "hello",
      "world"
    ]
    stdout_equal /orld/                      # 3
    stdout_equal [                           # 4
      "hello",
      /world|earth/
    ]
  end

In the example we see how the content can be specified:

1) as a string, with a newline (``\n``) character for each new line

2) as an array of lines

3) as a regexp that should match the file content given as a string

4) as an array of lines where some lines should match a regexp rather than be compared
   for string equality

Invoking ``cmdtest``
--------------------

``cmdtest`` can be called without any arguments at all. It will then look
for ``CMDTEST_*.rb`` files in the following places:

1) first ``t/CMDTEST_*.rb``

2) otherwise ``CMDTEST_*.rb``

If some command line arguments have been given, ``cmdtest`` will use
them instead of searching by itself. Some examples::

  $ cmdtest CMDTEST_foo.rb                   # just one file
  $ cmdtest CMDTEST_foo.rb CMDTEST_bar.rb    # two files
  $ cmdtest t                                # all CMDTEST_*.rb files in "t" dir
  $ cmdtest . t                              # all CMDTEST_*.rb files in both dirs


Reference Part
--------------

cmd
+++

The ``cmd`` method is the central method of the whole Cmdtest framework.
It should always be called with a block like this::

  cmd "some_prog ..." do
    assertion1 ...
    ...
    assertionN ...
  end

A block is used to make it easy to know when the last assertion has
been found.  The do-block should only contain assertions.  Cmdtest
applies some implicit assertions if the do-block is empty or misses
some kind of assertion::

  # all assertions implicit
  cmd "true" do
  end

  # exit status assertion explicit, but other assertions implicit
  cmd "true" do
    exit_zero
  end

See also the example in the `Structure of a test-method`_ section above.


Assertions - exit status
++++++++++++++++++++++++

``exit_nonzero``
    The command should have exited with a non-zero exit status (i.e. it
    should have failed).

``exit_status(status)``
    The command should have exited with the specified exit status.

``exit_zero``
    The command should have exited with a zero exit status (i.e. it
    should have succeeded). This is the default if none of the other
    exit-related methods have been called.

Assertions - files
++++++++++++++++++

``affected_files(file1,...,fileN)``
    The specified files should have been created, removed or modified by the
    command. This assertion can be used when it doesn't matter which
    of ``created_files``, ``removed_files`` or ``modified_files`` that apply
    (cf. ``written_files``).

``created_files(file1,...,fileN)``
    The specified files should have been created by the command.

``modified_files(file1,...,fileN)``
    The specified files should have been modified by the command. A
    file is considered modified if it existed before the command, and
    something about the file has changed after the command (inode
    number, modification date or content).

``removed_files(file1,...,fileN)``
    The specified files should have been removed by the command.

``written_files(file1,...,fileN)``
    The specified files should have been created or modified by the
    command. This assertion can be used when it doesn't matter which
    of ``created_files`` or ``modified_files`` that apply. A typical scenario is
    in a test method where repeated operations are done on the same
    file. By using ``written_files`` we don't have to treat the first
    case special (when the file is created).

Assertions - stdout/stderr/file content
+++++++++++++++++++++++++++++++++++++++

``file_equal(file, content)``
    Assert that the specified file matches the given content.
    See "stdout_equal" for how "content" can be specified.

``file_not_equal(file, content)``
    Like ``file_equal`` but with inverted test.

``stderr_equal(content)``
    Assert that the standard error of the command matches the given content.
    See "stdout_equal" for how "content" can be specified.

``stderr_not_equal(content)``
    Like ``stderr_equal`` but with inverted test.

``stdout_equal(content)``
    Assert that the standard output of the command matches the given content.
    The content can be given in several different forms: 1) as a
    string that should be equal to the entire file, 2) as an array of
    lines that should be equal to the entire file, 3) as a regexp that
    should match the entire file (given as one string).
    For more details and examples see the section "Matching standard output content".

``stdout_not_equal(content)``
    Like ``stdout_equal`` but with inverted test.


Assertions - misc
+++++++++++++++++

``assert(flag, msg=nil)``
    Assert that ``flag`` is true. This assertion is a last resort, when no other
    assertion fits. Should normally not be used.


Helper functions
++++++++++++++++

``create_file(filename, content)``
    Create a file inside the "work directory".
    The content can be specified either as an array of lines or as
    a string with the content of the whole file.
    The filename is evaluated relative to the current directory at the
    time of the call.

``ignore_file(file)``
    Ignore the specified file when looking for differences in the filesystem.

``ignore_files(file1, ..., fileN)``
    Ignore the specified files when looking for differences in the filesystem.

``import_file(src, tgt)``
    Copy a file from outside of the "work directory" to inside.
    The ``src`` path is evaluated relative to the current directory
    when ``cmdtest`` was called. The ``tgt`` is evaluated relative to
    the current directory inside the "work directory" at the time
    of the call.

``prepend_path(dir)``
    Prepend the given directory to the ``PATH`` so commands executed via ``cmd``
    are looked up using the modified ``PATH``. A typical use is to add the directory
    where the executable tested is located. The argument ``dir`` is evaluated
    relative to the current directory  in effect when ``cmdtest`` was invoked.


``touch_file(filename)``
    "touch" a file inside the "work directory".
    The filename is evaluated relative to the current directory at the
    time of the call.

.. _`unit testing`: http://en.wikipedia.org/wiki/Unit_testing
.. _`junit`:        http://en.wikipedia.org/wiki/JUnit
.. _`Test::Unit`:   http://www.ruby-doc.org/stdlib/libdoc/test/unit/rdoc/classes/Test/Unit.html

.. _`continuous integration`: http://en.wikipedia.org/wiki/Continuous_integration
.. _Hudson: https://hudson.dev.java.net