This documentation is a collection of the most common use cases, and their solutions. If you have not used this library before, it may be better to read the :ref:`tutorial` first.
To match query parameters, you must not included them to the URI, as this will not work:
.. literalinclude :: ../tests/examples/test_howto_query_params_never_do_this.py :language: python
There's an explicit place where the query string should go:
.. literalinclude :: ../tests/examples/test_howto_query_params_proper_use.py :language: python
The query_string is the parameter which does not contain the leading
question mark ?.
Note
The reason behind this is the underlying http server library werkzeug,
which provides the Request object which is used for the matching the
request with the handlers. This object has the query_string attribute
which contains the query.
As the order of the parameters in the query string usually does not matter, you
can specify a dict for the query_string parameter (the naming may look a bit
strange but we wanted to keep API compatibility and this dict matching feature
was added later).
.. literalinclude :: ../tests/examples/test_howto_query_params_dict.py :language: python
In the example above, both requests pass the test as we specified the expected query string as a dictionary.
Behind the scenes an additional step is done by the library: it parses up the query_string into the dict and then compares it with the dict provided.
The simplest form of URI matching is providing as a string. This is a equality match, if the URI of the request is not equal with the specified one, the request will not be handled.
If this is not desired, you can specify a regexp object (returned by the
re.compile() call).
.. literalinclude :: ../tests/examples/test_howto_regexp.py :language: python
The above will match every URI starting with "/foo".
There's an additional way to extend this functionality. You can specify your own
method which will receive the URI. All you need is to subclass from the
URIPattern class and define the match() method which will get the uri as
string and should return a boolean value.
.. literalinclude :: ../tests/examples/test_howto_url_matcher.py :language: python
When doing http digest authentication, the client may send a request like this:
GET /dir/index.html HTTP/1.0
Host: localhost
Authorization: Digest username="Mufasa",
realm="[email protected]",
nonce="dcd98b7102dd2f0e8b11d0f600bfb0c093",
uri="/dir/index.html",
qop=auth,
nc=00000001,
cnonce="0a4f113b",
response="6629fae49393a05397450978507c4ef1",
opaque="5ccc069c403ebaf9f0171e9517f40e41"
Implementing a matcher is difficult for this request as the order of the
parameters in the Authorization header value is arbitrary.
By default, pytest-httpserver includes an Authorization header parser so the
order of the parameters in the Authorization header does not matter.
.. literalinclude :: ../tests/examples/test_howto_authorization_headers.py :language: python
Matching the request data can be done in two different ways. One way is to provide a python string (or bytes object) whose value will be compared to the request body.
When the request contains a json, matching to will be error prone as an object can be represented as json in different ways, for example when different length of indentation is used.
To match the body as json, you need to add the python data structure (which could be dict, list or anything which can be the result of json.loads() call). The request's body will be loaded as json and the result will be compared to the provided object. If the request's body cannot be loaded as json, the matcher will fail and pytest-httpserver will proceed with the next registered matcher.
Example:
.. literalinclude :: ../tests/examples/test_howto_json_matcher.py :language: python
Note
JSON requests usually come with Content-Type: application/json header.
pytest-httpserver provides the headers parameter to match the headers of
the request, however matching json body does not imply matching the
Content-Type header. If matching the header is intended, specify the expected
Content-Type header and its value to the headers parameter.
Note
json and data parameters are mutually exclusive so both of then cannot be specified as in such case the behavior is ambiguous.
Note
The request body is decoded by using the data_encoding parameter, which is default to utf-8. If the request comes in a different encoding, and the decoding fails, the request won't match with the expected json.
For each http header, you can specify a callable object (eg. a python function) which will be called with the header name, header actual value and the expected value, and will be able to determine the matching.
You need to implement such a function and then use it:
.. literalinclude :: ../tests/examples/test_howto_case_insensitive_matcher.py :language: python
Note
Header value matcher is the basis of the Authorization header parsing.
If you want to change the matching of only one header, you may want to use the
HeaderValueMatcher class.
In case you want to do it globally, you can add the header name and the callable
to the HeaderValueMatcher.DEFAULT_MATCHERS dict.
from pytest_httpserver import HeaderValueMatcher
def case_insensitive_compare(actual: str, expected: str) -> bool:
return actual.lower() == expected.lower()
HeaderValueMatcher.DEFAULT_MATCHERS["X-Foo"] = case_insensitive_compare
def test_case_insensitive_matching(httpserver: HTTPServer):
httpserver.expect_request("/", headers={"X-Foo": "bar"}).respond_with_data("OK")
assert (
requests.get(httpserver.url_for("/"), headers={"X-Foo": "bar"}).status_code
== 200
)
assert (
requests.get(httpserver.url_for("/"), headers={"X-Foo": "BAR"}).status_code
== 200
)In case you don't want to change the defaults, you can provide the
HeaderValueMatcher object itself.
.. literalinclude :: ../tests/examples/test_howto_header_value_matcher.py :language: python
In the case the response is not static, for example it depends on the request,
you can pass a function to the respond_with_handler function. This function
will be called with a request object and it should return a Response object.
.. literalinclude :: ../tests/examples/test_howto_custom_handler.py :language: python
The above code implements a handler which returns a random number between 1 and 10. Not particularly useful but shows that the handler can return any computed or derived value.
In the response handler you can also use the assert statement, similar to
the tests, but there's a big difference. As the server is running in its own
thread, this will cause a HTTP 500 error returned, and the exception registered
into a list. To get that error, you need to call check_assertions() method
of the httpserver.
In case you want to ensure that there was no other exception raised which was
unhandled, you can call the check_handler_errors() method of the httpserver.
Two notable examples for this:
.. literalinclude :: ../tests/examples/test_howto_check_handler_errors.py :language: python
If you want to call both methods (check_handler_errors() and
check_assertions()) you can call the check() method, which will call
these.
.. literalinclude :: ../tests/examples/test_howto_check.py :language: python
Note
The scope of the errors checked by the check() method may
change in the future - it is added to check all possible errors happened in
the server.
By default, the server run by pytest-httpserver will listen on localhost on a random available port. In most cases it works well as you want to test your app in the local environment.
If you need to change this behavior, there are a plenty of options. It is very important to make these changes before starting the server, eg. before running any test using the httpserver fixture.
Use IP address 0.0.0.0 to listen globally.
Warning
You should be careful when listening on a non-local ip (such as 0.0.0.0). In this case anyone knowing your machine's IP address and the port can connect to the server.
Set PYTEST_HTTPSERVER_HOST and/or PYTEST_HTTPSERVER_PORT environment
variables to the desired values.
Changing HTTPServer.DEFAULT_LISTEN_HOST and
HTTPServer.DEFAULT_LISTEN_PORT attributes. Make sure that you do this before
running any test requiring the httpserver fixture. One ideal place for this
is putting it into conftest.py.
Overriding the httpserver_listen_address fixture. Similar to the solutions
above, this needs to be done before starting the server (eg. before referencing
the httpserver fixture).
import pytest
@pytest.fixture(scope="session")
def httpserver_listen_address():
return ("127.0.0.1", 8000)When your client runs in a thread, everything completes without waiting for the first response. To overcome this problem, you can wait until all the handlers have been served or there's some error happened.
This is available only for oneshot and ordered handlers, as permanent handlers last forever.
To have this feature enabled, use the context object returned by the wait()
method of the httpserver object.
This method accepts the following parameters:
- raise_assertions: whether raise assertions on unexpected request or timeout or not
- stop_on_nohandler: whether stop on unexpected request or not
- timeout: time (in seconds) until time is out
Behind the scenes it synchronizes the state of the server with the main thread.
Last, you need to assert on the result attribute of the context object.
.. literalinclude :: ../tests/examples/test_howto_wait_success.py :language: python
In the above code, all the request.get() calls could be in a different thread, eg. running in parallel, but the exit condition of the context object is to wait for the specified conditions.
If by any chance, you want to emulate network errors such as Connection reset by peer or Connection refused, you can simply do it by connecting to a random port number where no service is listening:
.. literalinclude :: ../tests/examples/test_howto_timeout_requests.py :language: python
However, connecting to the port where the httpserver had been started will still succeed as the server is running continuously. This is working by design as starting/stopping the server is costly.
import pytest
import requests
# setting a fixed port for httpserver
@pytest.fixture(scope="session")
def httpserver_listen_address():
return ("127.0.0.1", 8000)
# this test will pass
def test_normal_connection(httpserver):
httpserver.expect_request("/foo").respond_with_data("foo")
assert requests.get("http://localhost:8000/foo").text == "foo"
# this tess will FAIL, as httpserver started in test_normal_connection is
# still running
def test_connection_refused():
with pytest.raises(requests.exceptions.ConnectionError):
# this won't get Connection refused error as the server is still
# running.
# it will get HTTP status 500 as the handlers registered in
# test_normal_connection have been removed
requests.get("http://localhost:8000/foo")To solve the issue, the httpserver can be stopped explicitly. It will start
implicitly when the first test starts to use it. So the
test_connection_refused test can be re-written to this:
def test_connection_refused(httpserver):
httpserver.stop() # stop the server explicitly
with pytest.raises(requests.exceptions.ConnectionError):
requests.get("http://localhost:8000/foo")To emulate timeout, there's one way to register a handler function which will sleep for a given amount of time.
import time
from pytest_httpserver import HTTPServer
import pytest
import requests
def sleeping(request):
time.sleep(2) # this should be greater than the client's timeout parameter
def test_timeout(httpserver: HTTPServer):
httpserver.expect_request("/baz").respond_with_handler(sleeping)
with pytest.raises(requests.exceptions.ReadTimeout):
assert requests.get(httpserver.url_for("/baz"), timeout=1)There's one drawback though: the test takes 2 seconds to run as it waits the handler thread to be completed.
To run an https server, trustme can be used to do the heavy lifting:
@pytest.fixture(scope="session")
def ca():
return trustme.CA()
@pytest.fixture(scope="session")
def httpserver_ssl_context(ca):
context = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
localhost_cert = ca.issue_cert("localhost")
localhost_cert.configure_cert(context)
return context
@pytest.fixture(scope="session")
def httpclient_ssl_context(ca):
with ca.cert_pem.tempfile() as ca_temp_path:
return ssl.create_default_context(cafile=ca_temp_path)
@pytest.mark.asyncio
async def test_aiohttp(httpserver, httpclient_ssl_context):
import aiohttp
httpserver.expect_request("/").respond_with_data("hello world!")
connector = aiohttp.TCPConnector(ssl=httpclient_ssl_context)
async with aiohttp.ClientSession(connector=connector) as session:
async with session.get(httpserver.url_for("/")) as result:
assert (await result.text()) == "hello world!"
def test_requests(httpserver, ca):
import requests
httpserver.expect_request("/").respond_with_data("hello world!")
with ca.cert_pem.tempfile() as ca_temp_path:
result = requests.get(httpserver.url_for("/"), verify=ca_temp_path)
assert result.text == "hello world!"
def test_httpx(httpserver, httpclient_ssl_context):
import httpx
httpserver.expect_request("/").respond_with_data("hello world!")
result = httpx.get(httpserver.url_for("/"), verify=httpclient_ssl_context)
assert result.text == "hello world!"pytest-httpserver can only listen on one address and it also means that address family is determined by that. As it relies on Werkzeug, it passes the provided host parameter to it and then it is up to Werkzeug how the port binding is done.
Werkzeug determines the address family by examining the string provided. If it
contains a colon (:) then it will be an IPv6 (AF_INET6) socket, otherwise, it
will be an IPv4 (AF_INET) socket. The default string in pytest-httpserver is
localhost so by default, the httpserver listens on IPv4. If you want it to
listen on IPv6 address, provide an IPv6 address (::1 for example) to it.
It should be noted that dual-stack systems are still working with
pytest-httpserver because the clients obtain the possible addresses for the a
given name by calling getaddrinfo() or similar function which returns the
addresses together with address families, and the client iterates over this
list. In the case when pytest-httpserver is listening on 127.0.0.1, and
the client uses localhost name in the url, it will try ::1 first, and
then it will move on to 127.0.0.1, which will succeed, or vica-versa, where
127.0.0.1 will be successful first.
If you want to test a connection error case in your test (such as TLS error),
the client can fail in a strange way as we seen in this issue. In such case,
client tries with 127.0.0.1 first, then reaches a TLS error (which is normal
as the test case is about testing for the TLS issue), then it moves on to
::1, then it fails with Connection reset. In such case fixing the bind
address to 127.0.0.1 (and thereby fixing the host part of the URL returned
by the url_for call) solves the issue as the client will receive the address
(127.0.0.1) instead of the name (localhost) so it won't move on to the
IPv6 address.
In this mode, the code which is being tested (the client) is executed in a background thread, while the server events are synchronized to the main thread, so it looks like it is running in the main thread. This allows to catch the assertions occured on the server side synchronously, and assertions are raised to the main thread. You need to call check_assertions at the end for only the unexpected requests.
This is an experimental feature so pytest-httpserver has no fixture for it yet. If you find this feature useful any you have ideas or suggestions related to this, feel free to open an issue.
Example:
.. literalinclude :: ../tests/examples/test_example_blocking_httpserver.py :language: python
pytest-httpserver keeps a log of request-response pairs in a python list. This
log can be accessed by the log attibute of the httpserver instance, but
there are methods made specifically to query the log.
Each of the log querying methods accepts a :py:class:`pytest_httpserver.RequestMatcher` object which uses the same matching logic which is used by the server itself. Its parameters are the same to the parameters specified for the server's except_request (and the similar) methods.
The methods for querying:
- :py:meth:`pytest_httpserver.HTTPServer.get_matching_requests_count` returns how many requests are matching in the log as an int
- :py:meth:`pytest_httpserver.HTTPServer.assert_request_made` asserts the given amount of requests are matching in the log. By default it checks for one (1) request but other value can be specified. For example, 0 can be specified to check for requests not made.
- :py:meth:`pytest_httpserver.HTTPServer.iter_matching_requests` is a generator yielding Request-Response tuples of the matching entries in the log. This offers greater flexibility (compared to the other methods)
Example:
.. literalinclude :: ../tests/examples/test_howto_log_querying.py :language: python
pytest-httpserver serves the request in a single-threaded, blocking way. That means that if multiple requests are made to it, those will be served one by one.
There can be cases where parallel processing is required, for those cases pytest-httpserver allows running a server which start one thread per request handler, so the requests are served in parallel way (depending on Global Interpreter Lock this is not truly parallel, but from the I/O point of view it is).
To set this up, you have two possibilities.
One is to customize how the HTTPServer object is created. This is possible by defining the following fixture:
@pytest.fixture(scope="session")
def make_httpserver() -> Iterable[HTTPServer]:
server = HTTPServer(threaded=True) # set threaded=True to enable thread support
server.start()
yield server
server.clear()
if server.is_running():
server.stop()This will override the httpserver fixture in your tests.
This way, you can create a different httpserver fixture and you can use it besides the main one.
@pytest.fixture()
def threaded() -> Iterable[HTTPServer]:
server = HTTPServer(threaded=True)
server.start()
yield server
server.clear()
if server.is_running():
server.stop()
def test_threaded(threaded: HTTPServer): ...This will start and stop the server for each tests, which causes about 0.5
seconds waiting when the server is stopped. It won't override the httpserver
fixture so you can keep the original single-threaded behavior.
Warning
Handler threads which are still running when the test is finished, will be left behind and won't be join()ed between the tests. If you want to ensure that all threads are properly cleaned up and you want to wait for them, consider using the second option (:ref:`Creating a different httpserver fixture`) described above.
Sometimes there's a need to add side effects to the handling of the requests. Such side effect could be adding some amount of delay to the serving or adding some garbage to response data.
While these can be achieved by using :py:meth:`pytest_httpserver.RequestHandler.respond_with_handler` where you can implement your own function to serve the request, pytest-httpserver provides a hooks API where you can add side effects to request handlers such as :py:meth:`pytest_httpserver.RequestHandler.respond_with_json` and others. This allows to use the existing API of registering handlers.
Example:
.. literalinclude :: ../tests/examples/test_howto_hooks.py
:language: python
:py:mod:`pytest_httpserver.hooks` module provides some pre-defined hooks to use.
You can implement your own hook as well. The requirement is to have a callable
object (a function) Callable[[Request, Response], Response]. In details:
- Parameter :py:class:`werkzeug.Request` which represents the request sent by the client.
- Parameter :py:class:`werkzeug.Response` which represents the response made by the handler.
- Returns a :py:class:`werkzeug.Response` object which represents the response will be returned to the client.
Example:
.. literalinclude :: ../tests/examples/test_howto_custom_hooks.py
:language: python
with_post_hook can be called multiple times, in this case pytest-httpserver
will register the hooks, and hooks will be called sequentially, one by one. Each
hook will receive the response what the previous hook returned, and the last
hook called will return the final response which will be sent back to the client.