Trestle is a nose plugin that enables you to write testable documentation for web apps (or shell commands, but more on that later).
To use trestle, write a reStructured Text document (like this one) using a set of special directives to indicate the fixtures to be used for testing (including the http or mock http client), each request to be sent via the client, and the expected response from the application under test.
A simple trestle test document might look like this:
Frog: A web service for doing things with frogs ----------------------------------------------- .. fixtures :: frog_fixtures Frog is a web service for doing things with frogs. You can list the available frogs. .. request :: List available frogs GET /frogs .. The response is in a plain-text format. .. response :: bullfrog poison dart treefrog ... .. You can find out if something is a frog. .. request :: Get bullfrog details GET /frogs/bullfrog .. If the requested term is a frog, details about the frog will be returned. .. response :: Bullfrogs are really big frogs. .. Otherwise, a 404 response is returned. .. request :: Get details for a non-frog GET /frogs/toad .. .. response :: 404 ... ... "toad" is not a frog. .. You can create frogs. .. request :: Create a frog POST /frogs/pouched+frog A pouched frog camouflages itself to look like dead leaves. .. .. response :: 201 Created ... ... ..
Fixtures for a trestle test file are set like so:
.. fixtures:: about
A fixtures directive is required in every document to be tested. The directive must name a python module. The module must include the following attribute:
And may include the following functions:
Tests in a trestle document consist of a .. request directive, followed by one or more .. response directives. The .. request directive defines the request to be sent to the web app under test, using the client defined in the fixtures module.
A simple request directive looks like this:
.. request:: A simple get GET /foo/bar ..
If the request is a POST or PUT that includes data to be sent, include that data in the body of the request, after the request line:
.. request:: A post POST /foo/bar a=1&b=2 ..
The response expected to be returned to the client is defined using a response block:
.. response:: Ponies!!1! ..
Note
Conclude each block with .. alone on a line to avoid rst parsing errors that can result in text following a block being thrown away.
The testing process is simple: each request is executed using the client defined in the fixtures module, and each expected response following that request in the text is compared against the actual response. If all responses match, the test passes. Otherwise, it fails.
Passing examples are given a pleasing green background, failures a sinister red. Details of the failed match are included following the failed example.
At times it may be necessary to execute a unique fixture before executing a request. While it's usually better to make the test depend only on public apis and not internal details or externalities, sometimes (e.g. when testing time-dependent operations) that isn't possible or reasonable. For those times, use the :setup: argument to the request. The body of the exec argument will be evaluated in the context of the fixture module before running the request. Naturally, there is also a :teardown: argument, which will be executed after the request is run and the response processed. Here's an example:
.. request:: Get something special :setup: client.set_special(true) :teardown: client.set_special(false) GET /special ..
Trestle also supports shell examples. When a shell example is executed, the shell command given is executed, and the stdout produced by the command is compared to the body of the ..shell example using the normal doctest output checker. A simple shell example looks like this:
.. shell :: echo "Hello" Hello ..
The application used by this self test is very simple: it always replies with 'Hello' to GET requests, unless special mode is active. Let's start the test examples with a simple GET request.
GET /foo
A simple get
You can match on the whole response -- be sure to always include both the full status line and headers:
200 Ok Content-type: text/plain Hello
Or just the content. Notice that multiple response blocks can be compared against the same request.
Hello
The output comparison is done using a doctest OutputChecker. The doctest extensions NORMALIZE_WHITESPACE and ELLIPSIS are always on, so this response also matches:
200 ... ... He...o
POST requests include the data to be posted after the request line.
POST /foo a=1&b=2
A simple POST
The simple application used in this self test always responds to POST requests by echoing back the posted parameters:
You said: a=1 and b=2
Just like with GETs, you can match against headers and content or content only.
200 Ok Content-type: text/plain You said: a=1 and b=2
Fixture code may be run around a request.
GET /special
A special request requiring its own fixture.
SPECIAL is set.
GET /special
Without the fixture
SPECIAL is not set.
A simple shell example.
echo "Hello"
Hello
Here is the source of the fixtures file used with this test:
from paste.fixture import TestApp
from cgi import parse_qsl
def app(environ, start_response):
start_response('200 Ok', [('Content-type', 'text/plain')])
if environ['REQUEST_METHOD'] == 'GET':
return ['Hello']
elif environ['REQUEST_METHOD'] == 'POST':
post_data = str(environ['wsgi.input'].read())
params = parse_qsl(post_data)
return ['You said: ',
' and '.join('%s=%s' % p for p in params)]
def setup_all(cls):
pass
def teardown_all(cls):
pass
def setup_each(inst):
pass
def teardown_each(inst):
pass
class SpecialTestApp(TestApp):
special = False
def get(self, url, *arg, **kw):
if url == '/special':
if self.special:
r = "SPECIAL is set."
else:
r = "SPECIAL is not set."
res = self._make_response(('200 OK', [], r, []), 0)
return res
return super(SpecialTestApp, self).get(url, *arg, **kw)
def setup_special(self):
self.special = True
def teardown_special(self):
self.special = False
client = SpecialTestApp(app)
And the source of the test document itself:
Trestle: doctest for REST(ful services)
---------------------------------------
.. fixtures:: about
.. contents::
About
~~~~~
Trestle is a nose plugin that enables you to write testable documentation for
web apps (or shell commands, but more on that later).
To use trestle, write a `reStructured Text`_ document (like this one) using a
set of special directives to indicate the **fixtures** to be used for testing
(including the http or mock http client), each **request** to be sent via the
client, and the **expected response** from the application under test.
A simple trestle test document might look like this::
Frog: A web service for doing things with frogs
-----------------------------------------------
.. fixtures :: frog_fixtures
Frog is a web service for doing things with frogs.
You can list the available frogs.
.. request :: List available frogs
GET /frogs
..
The response is in a plain-text format.
.. response ::
bullfrog
poison dart
treefrog
...
..
You can find out if something is a frog.
.. request :: Get bullfrog details
GET /frogs/bullfrog
..
If the requested term is a frog, details about the frog will be returned.
.. response ::
Bullfrogs are really big frogs.
..
Otherwise, a 404 response is returned.
.. request :: Get details for a non-frog
GET /frogs/toad
..
.. response ::
404 ...
...
"toad" is not a frog.
..
You can create frogs.
.. request :: Create a frog
POST /frogs/pouched+frog
A pouched frog camouflages itself to look like dead leaves.
..
.. response ::
201 Created
...
...
..
Trestle directives
^^^^^^^^^^^^^^^^^^
Fixtures for a trestle test file are set like so::
.. fixtures:: about
A fixtures directive is required in every document to be tested. The
directive must name a python module. The module must include the
following attribute:
client
A client application to be called with methods .get(), .post(),
.put(), etc. Each method must accept at least the arguments url and
data, and may accept others but may not require
them. `paste.fixtures.TestApp`_ is such a client, though it natively
supports only .get() and .post().
And may include the following functions:
setup_all(cls)
Setup fixture run before the first request.
teardown_all(cls)
Teardown fixture run after the last request.
setup_each(inst)
Setup fixture run before each request.
teardown_each(inst)
Teardown fixture run after each request.
Tests in a trestle document consist of a ``.. request`` directive, followed by
one or more ``.. response`` directives. The ``.. request`` directive defines
the request to be sent to the web app under test, using the client defined in
the fixtures module.
A simple request directive looks like this::
.. request:: A simple get
GET /foo/bar
..
If the request is a POST or PUT that includes data to be sent, include
that data in the body of the request, after the request line::
.. request:: A post
POST /foo/bar
a=1&b=2
..
The response expected to be returned to the client is defined using a
response block::
.. response::
Ponies!!1!
..
.. note:: Conclude each block with ``..`` alone on a line to avoid rst parsing
errors that can result in text following a block being thrown away.
The testing process is simple: each request is executed using the
client defined in the fixtures module, and each expected response
following that request in the text is compared against the actual
response. If all responses match, the test passes. Otherwise, it
fails.
.. raw:: html
<p>Passing examples are given a <span class="pass">pleasing green
background</span>, failures a <span class="fail">sinister red</span>.
Details of the failed match are included following the
failed example.</p>
Fixture commands
^^^^^^^^^^^^^^^^
At times it may be necessary to execute a unique fixture before executing a
request. While it's usually better to make the test depend only on public apis
and not internal details or externalities, sometimes (e.g. when testing
time-dependent operations) that isn't possible or reasonable. For those times,
use the **:setup:** argument to the request. The body of the exec argument
will be evaluated in the context of the fixture module before running the
request. Naturally, there is also a **:teardown:** argument, which will be
executed after the request is run and the response processed. Here's an
example::
.. request:: Get something special
:setup: client.set_special(true)
:teardown: client.set_special(false)
GET /special
..
Shell examples
^^^^^^^^^^^^^^
Trestle also supports shell examples. When a shell example is executed, the
shell command given is executed, and the stdout produced by the command is
compared to the body of the ``..shell`` example using the normal doctest
output checker. A simple shell example looks like this::
.. shell :: echo "Hello"
Hello
..
Examples
~~~~~~~~
The application used by this self test is very simple: it always replies with
'Hello' to GET requests, unless **special** mode is active. Let's start the
test examples with a simple GET request.
.. request:: A simple get
GET /foo
..
You can match on the whole response -- be sure to always include both
the full status line and headers:
.. response::
200 Ok
Content-type: text/plain
Hello
..
Or just the content. Notice that multiple response blocks can be
compared against the same request.
.. response::
Hello
..
The output comparison is done using a doctest OutputChecker. The
doctest extensions NORMALIZE_WHITESPACE and ELLIPSIS are always on, so
this response also matches:
.. response::
200 ...
...
He...o
..
----
POST requests include the data to be posted after the request line.
.. request:: A simple POST
POST /foo
a=1&b=2
..
The simple application used in this self test always responds to POST
requests by echoing back the posted parameters:
.. response::
You said: a=1 and b=2
..
Just like with GETs, you can match against headers and content or content only.
.. response::
200 Ok
Content-type: text/plain
You said: a=1 and b=2
..
----
Fixture code may be run around a request.
.. request:: A special request requiring its own fixture.
:setup: client.setup_special()
:teardown: client.teardown_special()
GET /special
..
.. response ::
SPECIAL is set.
..
.. request:: Without the fixture
GET /special
..
.. response::
SPECIAL is not set.
..
----
A simple shell example.
.. shell :: echo "Hello"
Hello
..
Source
~~~~~~
Here is the source of the fixtures file used with this test:
.. include:: about.py
:literal:
And the source of the test document itself:
.. include:: about.rst
:literal:
.. _`reStructured Text`: http://docutils.sourceforge.net/rst.html`
.. _`paste.fixtures.TestApp` : http://pythonpaste.org/testing-applications.html