Testing Applications with WebTest +++++++++++++++++++++++++++++++++ :author: Ian Bicking .. toctree:: :maxdepth: 3 license modules/webtest .. contents:: .. comment: >>> from dtopt import ELLIPSIS Status & License ================ WebTest is an extraction of ``paste.fixture.TestApp``, rewriting portions to use `WebOb `_. It is under active development as part of the Paste cloud of packages. Feedback and discussion should take place on the `Paste list `_, and bugs should go into the `Paste Trac instance `_. This library is licensed under an `MIT-style license `_. WebTest is in an svn repository at `http://svn.pythonpaste.org/Paste/WebTest/trunk `_. You can check it out with:: $ svn co http://svn.pythonpaste.org/Paste/WebTest/trunk WebTest What This Does ============== WebTest helps you test your WSGI-based web applications. This can be any application that has a WSGI interface, including an application written in a framework that supports WSGI (which includes most actively developed Python web frameworks -- almost anything that even nominally supports WSGI should be testable). With this you can test your web applications without starting an HTTP server, and without poking into the web framework shortcutting pieces of your application that need to be tested. The tests WebTest runs are entirely equivalent to how a WSGI HTTP server would call an application. By testing the full stack of your application, the WebTest testing model is sometimes called a *functional test*, *integration test*, or *acceptance test* (though the latter two are not particularly good descriptions). This is in contrast to a *unit test* which tests a particular piece of functionality in your application. While complex programming tasks are often is suited to unit tests, template logic and simple web programming is often best done with functional tests; and regardless of the presence of unit tests, no testing strategy is complete without high-level tests to ensure the entire programming system works together. WebTest helps you create tests by providing a convenient interface to run WSGI applications and verify the output. TestApp ======= The most important object in WebTest is ``webtest.TestApp``, the wrapper for WSGI applications. To use it, you simply instantiate it with your WSGI application. (Note: if your WSGI application requires any configuration, you must set that up manually in your tests.) .. code-block:: python >>> from webtest import TestApp >>> from webob import Request, Response >>> from paste.urlmap import URLMap >>> map_app = URLMap() >>> form_html = map_app['/form.html'] = Response(content_type='text/html') >>> form_html.body = ''' ... ''' >>> app = TestApp(map_app) >>> res = app.get('/form.html') >>> res.status '200 OK' >>> res.form Making Requests --------------- To make a request, use: .. code-block:: python app.get('/path', [headers], [extra_environ], ...) This does a request for ``/path``, with any extra headers or WSGI environment keys that you indicate. This returns a response object, based on `webob.Response `_. It has some additional methods to make it easier to test. If you want to do a POST request, use: .. code-block:: python app.post('/path', {'vars': 'values'}, [headers], [extra_environ], [upload_files], ...) Specifically the second argument is the *body* of the request. You can pass in a dictionary (or dictionary-like object), or a string body (dictionary objects are turned into HTML form submissions). You can also pass in the keyword argument upload_files, which is a list of ``[(fieldname, filename, fild_content)]``. File uploads use a different form submission data type to pass the structured data. For other verbs you can use: app.put(path, params, ...) app.delete(path, ...) These do PUT and DELETE requests. Modifying the Environment & Simulating Authentication ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The best way to simulate authentication is if your application looks in ``environ['REMOTE_USER']`` to see if someone is authenticated. Then you can simply set that value, like: .. code-block:: python app.get('/secret', extra_environ=dict(REMOTE_USER='bob')) If you want *all* your requests to have this key, do: .. code-block:: python app = TestApp(my_app, extra_environ=dict(REMOTE_USER='bob')) What Is Tested By Default ~~~~~~~~~~~~~~~~~~~~~~~~~ A key concept behind WebTest is that there's lots of things you shouldn't have to check everytime you do a request. It is assumed that the response will either be a 2xx or 3xx response; if it isn't an exception will be raised (you can override this for a request, of course). The WSGI application is tested for WSGI compliance with a slightly modified version of `wsgiref.validate `_ (modified to support arguments to ``InputWrapper.readline``) automatically. Also it checks that nothing is printed to the ``environ['wsgi.errors']`` error stream, which typically indicates a problem (one that would be non-fatal in a production situation, but if you are testing is something you should avoid). To indicate another status is expected, use the keyword argument ``status=404`` to (for example) check that it is a 404 status, or ``status="*"`` to allow any status. If you expect errors to be printed, use ``expect_errors=True``. The Response Object ------------------- The response object is based on `webob.Response `_ with some additions to help with testing. The inherited attributes that are most interesting: ``response.status``: The text status of the response, e.g., ``"200 OK"``. ``response.headers``: A dictionary-like object of the headers in the response. ``response.body``: The text body of the response. ``response.request``: The `webob.Request object `_ used to generate this response. The added methods: ``response.follow(**kw)``: Follows the redirect, returning the new response. It is an error if this response wasn't a redirect. Any keyword arguments are passed to ``app.get`` (e.g., ``status``). ``x in response``: Returns True if the string is found in the response body. Whitespace is normalized for this test. ``response.mustcontain(string1, string2, ...)``: Raises an error if any of the strings are not found in the response. It also prints out the response in that case, so you can see the real response. ``response.showbrowser()``: Opens the HTML response in a browser; useful for debugging. ``str(response)``: Gives a slightly-compacted version of the response. This is compacted to remove newlines, making it easier to use with `doctest `_ ``response.click(description=None, linkid=None, href=None, anchor=None, index=None, verbose=False)``: Clicks the described link (`see docstring for more <./class-webtest.TestResponse.html#click>`_) ``response.forms``: Return a dictionary of forms; you can use both indexes (refer to the forms in order) or the string ids of forms (if you've given them ids) to identify the form. See `Form Submissions <#form-submissions>`_ for more on the form objects. ``response.form``: If there is just a single form, this returns that. It is an error if you use this and there are multiple forms. Form Submissions ================ You can fill out and submit forms from your tests. First you get the form: .. code-block:: python >>> res = app.get('/form.html') >>> form = res.form Then you fill it in fields: .. code-block:: python >>> form.action '/form-submit' >>> form.method 'POST' >>> # dict of fields >>> fields = form.fields.items(); fields.sort(); fields [('name', []), ('submit', [])] >>> form['name'] = 'Bob' >>> # When names don't point to a single field: >>> form.set('name', 'Bob', index=0) Then you can submit. First we'll put up a simple test app to catch the response: .. code-block:: python >>> from webtest.debugapp import debug_app >>> map_app['/form-submit'] = debug_app Then submit: .. code-block:: python >>> # Submit with no particular submit button pressed: >>> res = form.submit() >>> # Or submit a button: >>> res = form.submit('submit') >>> print res Response: 200 OK Content-Type: text/plain ... -- Body ---------- submit=Submit%21&name=Bob Select fields can only be set to valid values (i.e., values in an ``