Testing WSGI Applications — Werkzeug Documentation (3.1.x)

# Testing WSGI Applications

## Test Client

Werkzeug provides a `Client` to simulate requests to a WSGI application without starting a server. The client has methods for making different types of requests, as well as managing cookies across requests.

    >>> from werkzeug.test import Client
    >>> from werkzeug.testapp import test_app
    >>> c = Client(test_app)
    >>> response = c.get("/")
    >>> response.status_code
    200
    >>> response.headers
    Headers([('Content-Type', 'text/html; charset=utf-8'), ('Content-Length', '5211')])
    >>> response.get_data(as_text=True)
    '<!doctype html>...'

The client’s request methods return instances of `TestResponse`. This provides extra attributes and methods on top of `Response` that are useful for testing.

## Request Body

By passing a dict to `data`, the client will construct a request body with file and form data. It will set the content type to `application/x-www-form-urlencoded` if there are no files, or `multipart/form-data` there are.

    import io

    response = client.post(data={
        "name": "test",
        "file": (BytesIO("file contents".encode("utf8")), "test.txt")
    })

Pass a string, bytes, or file-like object to `data` to use that as the raw request body. In that case, you should set the content type appropriately. For example, to post YAML:

    response = client.post(
        data="a: value\nb: 1\n", content_type="application/yaml"
    )

A shortcut when testing JSON APIs is to pass a dict to `json` instead of using `data`. This will automatically call `json.dumps()` and set the content type to `application/json`. Additionally, if the app returns JSON, `response.json` will automatically call `json.loads()`.

    response = client.post("/api", json={"a": "value", "b": 1})
    obj = response.json()

## Environment Builder

`EnvironBuilder` is used to construct a WSGI environ dict. The test client uses this internally to prepare its requests. The arguments passed to the client request methods are the same as the builder.

Sometimes, it can be useful to construct a WSGI environment manually. An environ builder or dict can be passed to the test client request methods in place of other arguments to use a custom environ.

    from werkzeug.test import EnvironBuilder
    builder = EnvironBuilder(...)
    # build an environ dict
    environ = builder.get_environ()
    # build an environ dict wrapped in a request
    request = builder.get_request()

The test client responses make this available through `TestResponse.request` and `response.request.environ`.

## API

class werkzeug.test.Client(application, response_wrapper=None, use_cookies=True, allow_subdomain_redirects=False)

  Simulate sending requests to a WSGI application without running a WSGI or HTTP server.

  Parameters:

    - application (WSGIApplication) – The WSGI application to make requests to.

    - response_wrapper (type[Response] | None) – A `Response` class to wrap response data with. Defaults to `TestResponse`. If it’s not a subclass of `TestResponse`, one will be created.

    - use_cookies (bool) – Persist cookies from `Set-Cookie` response headers to the `Cookie` header in subsequent requests. Domain and path matching is supported, but other cookie parameters are ignored.

    - allow_subdomain_redirects (bool) – Allow requests to follow redirects to subdomains. Enable this if the application handles subdomains and redirects between them.

  Changelog

  Changed in version 2.3: Simplify cookie implementation, support domain and path matching.

  Changed in version 2.1: All data is available as properties on the returned response object. The response cannot be returned as a tuple.

  Changed in version 2.0: `response_wrapper` is always a subclass of :class:`TestResponse`.

  Changed in version 0.5: Added the `use_cookies` parameter.

  get_cookie(key, domain='localhost', path='/')

    Return a `Cookie` if it exists. Cookies are uniquely identified by `(domain, path, key)`.

    Parameters:

      - key (str) – The decoded form of the key for the cookie.

      - domain (str) – The domain the cookie was set for.

      - path (str) – The path the cookie was set for.

    Return type:

      Cookie | None

    Changelog

    Added in version 2.3.

  set_cookie(key, value='', *, domain='localhost', origin_only=True, path='/', **kwargs)

    Set a cookie to be sent in subsequent requests.

    This is a convenience to skip making a test request to a route that would set the cookie. To test the cookie, make a test request to a route that uses the cookie value.

    The client uses `domain`, `origin_only`, and `path` to determine which cookies to send with a request. It does not use other cookie parameters that browsers use, since they’re not applicable in tests.

    Parameters:

      - key (str) – The key part of the cookie.

      - value (str) – The value part of the cookie.

      - domain (str) – Send this cookie with requests that match this domain. If `origin_only` is true, it must be an exact match, otherwise it may be a suffix match.

      - origin_only (bool) – Whether the domain must be an exact match to the request.

      - path (str) – Send this cookie with requests that match this path either exactly or as a prefix.

      - kwargs (Any) – Passed to `dump_cookie()`.

    Return type:

      None

    Changelog

    Changed in version 3.0: The parameter `server_name` is removed. The first parameter is `key`. Use the `domain` and `origin_only` parameters instead.

    Changed in version 2.3: The `origin_only` parameter was added.

    Changed in version 2.3: The `domain` parameter defaults to `localhost`.

  delete_cookie(key, *, domain='localhost', path='/')

    Delete a cookie if it exists. Cookies are uniquely identified by `(domain, path, key)`.

    Parameters:

      - key (str) – The decoded form of the key for the cookie.

      - domain (str) – The domain the cookie was set for.

      - path (str) – The path the cookie was set for.

    Return type:

      None

    Changelog

    Changed in version 3.0: The `server_name` parameter is removed. The first parameter is `key`. Use the `domain` parameter instead.

    Changed in version 3.0: The `secure`, `httponly` and `samesite` parameters are removed.

    Changed in version 2.3: The `domain` parameter defaults to `localhost`.

  open(*args, buffered=False, follow_redirects=False, **kwargs)

    Generate an environ dict from the given arguments, make a request to the application using it, and return the response.

    Parameters:

      - args (Any) – Passed to `EnvironBuilder` to create the environ for the request. If a single arg is passed, it can be an existing `EnvironBuilder` or an environ dict.

      - buffered (bool) – Convert the iterator returned by the app into a list. If the iterator has a `close()` method, it is called automatically.

      - follow_redirects (bool) – Make additional requests to follow HTTP redirects until a non-redirect status is returned. `TestResponse.history` lists the intermediate responses.

      - kwargs (Any)

    Return type:

      TestResponse

    Changelog

    Changed in version 2.1: Removed the `as_tuple` parameter.

    Changed in version 2.0: The request input stream is closed when calling `response.close()`. Input streams for redirects are automatically closed.

    Changed in version 0.5: If a dict is provided as file in the dict for the `data` parameter the content type has to be called `content_type` instead of `mimetype`. This change was made for consistency with `werkzeug.FileWrapper`.

    Changed in version 0.5: Added the `follow_redirects` parameter.

  get(*args, **kw)

    Call `open()` with `method` set to `GET`.

    Parameters:

      - args (Any)

      - kw (Any)

    Return type:

      TestResponse

  post(*args, **kw)

    Call `open()` with `method` set to `POST`.

    Parameters:

      - args (Any)

      - kw (Any)

    Return type:

      TestResponse

  put(*args, **kw)

    Call `open()` with `method` set to `PUT`.

    Parameters:

      - args (Any)

      - kw (Any)

    Return type:

      TestResponse

  delete(*args, **kw)

    Call `open()` with `method` set to `DELETE`.

    Parameters:

      - args (Any)

      - kw (Any)

    Return type:

      TestResponse

  patch(*args, **kw)

    Call `open()` with `method` set to `PATCH`.

    Parameters:

      - args (Any)

      - kw (Any)

    Return type:

      TestResponse

  options(*args, **kw)

    Call `open()` with `method` set to `OPTIONS`.

    Parameters:

      - args (Any)

      - kw (Any)

    Return type:

      TestResponse

  head(*args, **kw)

    Call `open()` with `method` set to `HEAD`.

    Parameters:

      - args (Any)

      - kw (Any)

    Return type:

      TestResponse

  trace(*args, **kw)

    Call `open()` with `method` set to `TRACE`.

    Parameters:

      - args (Any)

      - kw (Any)

    Return type:

      TestResponse

class werkzeug.test.TestResponse(response, status, headers, request, history=(), **kwargs)

  `Response` subclass that provides extra information about requests made with the test `Client`.

  Test client requests will always return an instance of this class. If a custom response class is passed to the client, it is subclassed along with this to support test information.

  If the test request included large files, or if the application is serving a file, call `close()` to close any open files and prevent Python showing a `ResourceWarning`.

  Changelog

  Changed in version 2.2: Set the `default_mimetype` to None to prevent a mimetype being assumed if missing.

  Changed in version 2.1: Response instances cannot be treated as tuples.

  Added in version 2.0: Test client methods always return instances of this class.

  Parameters:

    - response (Iterable[str] | Iterable[bytes])

    - status (str)

    - headers (Headers)

    - request (Request)

    - history (tuple[TestResponse, ...])

    - kwargs (t.Any)

  default_mimetype: str | None = None

    the default mimetype if none is provided.

  request: Request

    A request object with the environ used to make the request that resulted in this response.

  history: tuple[TestResponse, ...]

    A list of intermediate responses. Populated when the test request is made with `follow_redirects` enabled.

  property text: str

    The response data as text. A shortcut for `response.get_data(as_text=True)`.

    Changelog

    Added in version 2.1.

class werkzeug.test.Cookie(key, value, decoded_key, decoded_value, expires, max_age, domain, origin_only, path, secure, http_only, same_site)

  A cookie key, value, and parameters.

  The class itself is not a public API. Its attributes are documented for inspection with `Client.get_cookie()` only.

  Changelog

  Added in version 2.3.

  Parameters:

    - key (str)

    - value (str)

    - decoded_key (str)

    - decoded_value (str)

    - expires (datetime | None)

    - max_age (int | None)

    - domain (str)

    - origin_only (bool)

    - path (str)

    - secure (bool | None)

    - http_only (bool | None)

    - same_site (str | None)

  key: str

    The cookie key, encoded as a client would see it.

  value: str

    The cookie key, encoded as a client would see it.

  decoded_key: str

    The cookie key, decoded as the application would set and see it.

  decoded_value: str

    The cookie value, decoded as the application would set and see it.

  expires: datetime | None

    The time at which the cookie is no longer valid.

  max_age: int | None

    The number of seconds from when the cookie was set at which it is no longer valid.

  domain: str

    The domain that the cookie was set for, or the request domain if not set.

  origin_only: bool

    Whether the cookie will be sent for exact domain matches only. This is `True` if the `Domain` parameter was not present.

  path: str

    The path that the cookie was set for.

  secure: bool | None

    The `Secure` parameter.

  http_only: bool | None

    The `HttpOnly` parameter.

  same_site: str | None

    The `SameSite` parameter.

class werkzeug.test.EnvironBuilder(path='/', base_url=None, query_string=None, method='GET', input_stream=None, content_type=None, content_length=None, errors_stream=None, multithread=False, multiprocess=False, run_once=False, headers=None, data=None, environ_base=None, environ_overrides=None, mimetype=None, json=None, auth=None)

  This class can be used to conveniently create a WSGI environment for testing purposes. It can be used to quickly create WSGI environments or request objects from arbitrary data.

  The signature of this class is also used in some other places as of Werkzeug 0.5 (`create_environ()`, `Response.from_values()`, `Client.open()`). Because of this most of the functionality is available through the constructor alone.

  Files and regular form data can be manipulated independently of each other with the `form` and `files` attributes, but are passed with the same argument to the constructor: `data`.

  `data` can be any of these values:

  - a `str` or `bytes` object: The object is converted into an `input_stream`, the `content_length` is set and you have to provide a `content_type`.

  - a `dict` or `MultiDict`: The keys have to be strings. The values have to be either any of the following objects, or a list of any of the following objects:

    - a `file`-like object: These are converted into `FileStorage` objects automatically.

    - a `tuple`: The `add_file()` method is called with the key and the unpacked `tuple` items as positional arguments.

    - a `str`: The string is set as form data for the associated key.

  - a file-like object: The object content is loaded in memory and then handled like a regular `str` or a `bytes`.

  Parameters:

    - path (str) – the path of the request. In the WSGI environment this will end up as `PATH_INFO`. If the `query_string` is not defined and there is a question mark in the `path` everything after it is used as query string.

    - base_url (str | None) – the base URL is a URL that is used to extract the WSGI URL scheme, host (server name + server port) and the script root (`SCRIPT_NAME`).

    - query_string (t.Mapping[str, str] | str | None) – an optional string or dict with URL parameters.

    - method (str) – the HTTP method to use, defaults to `GET`.

    - input_stream (t.IO[bytes] | None) – an optional input stream. Do not specify this and `data`. As soon as an input stream is set you can’t modify `args` and `files` unless you set the `input_stream` to `None` again.

    - content_type (str | None) – The content type for the request. As of 0.5 you don’t have to provide this when specifying files and form data via `data`.

    - content_length (int | None) – The content length for the request. You don’t have to specify this when providing data via `data`.

    - errors_stream (t.IO[str] | None) – an optional error stream that is used for `wsgi.errors`. Defaults to `stderr`.

    - multithread (bool) – controls `wsgi.multithread`. Defaults to `False`.

    - multiprocess (bool) – controls `wsgi.multiprocess`. Defaults to `False`.

    - run_once (bool) – controls `wsgi.run_once`. Defaults to `False`.

    - headers (Headers | t.Iterable[tuple[str, str]] | None) – an optional list or `Headers` object of headers.

    - data (None | (t.IO[bytes] | str | bytes | t.Mapping[str, t.Any])) – a string or dict of form data or a file-object. See explanation above.

    - json (t.Mapping[str, t.Any] | None) – An object to be serialized and assigned to `data`. Defaults the content type to `"application/json"`. Serialized with the function assigned to `json_dumps`.

    - environ_base (t.Mapping[str, t.Any] | None) – an optional dict of environment defaults.

    - environ_overrides (t.Mapping[str, t.Any] | None) – an optional dict of environment overrides.

    - auth (Authorization | tuple[str, str] | None) – An authorization object to use for the `Authorization` header value. A `(username, password)` tuple is a shortcut for `Basic` authorization.

    - mimetype (str | None)

  Changelog

  Changed in version 3.0: The `charset` parameter was removed.

  Changed in version 2.1: `CONTENT_TYPE` and `CONTENT_LENGTH` are not duplicated as header keys in the environ.

  Changed in version 2.0: `REQUEST_URI` and `RAW_URI` is the full raw URI including the query string, not only the path.

  Changed in version 2.0: The default `request_class` is `Request` instead of `BaseRequest`.

  Added in version 2.0: Added the `auth` parameter.

  Added in version 0.15: The `json` param and `json_dumps()` method.

  Added in version 0.15: The environ has keys `REQUEST_URI` and `RAW_URI` containing the path before percent-decoding. This is not part of the WSGI PEP, but many WSGI servers include it.

  Changed in version 0.6: `path` and `base_url` can now be unicode strings that are encoded with `iri_to_uri()`.

  server_protocol = 'HTTP/1.1'

    the server protocol to use. defaults to HTTP/1.1

  wsgi_version = (1, 0)

    the wsgi version to use. defaults to (1, 0)

  request_class

    The default request class used by `get_request()`.

    alias of `Request`

  static json_dumps(obj, *, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, cls=None, indent=None, separators=None, default=None, sort_keys=False, **kw)

    The serialization function used when `json` is passed.

  classmethod from_environ(environ, **kwargs)

    Turn an environ dict back into a builder. Any extra kwargs override the args extracted from the environ.

    Changelog

    Changed in version 2.0: Path and query values are passed through the WSGI decoding dance to avoid double encoding.

    Added in version 0.15.

    Parameters:

      - environ (WSGIEnvironment)

      - kwargs (t.Any)

    Return type:

      EnvironBuilder

  property base_url: str

    The base URL is used to extract the URL scheme, host name, port, and root path.

  property content_type: str | None

    The content type for the request. Reflected from and to the `headers`. Do not set if you set `files` or `form` for auto detection.

  property mimetype: str | None

    The mimetype (content type without charset etc.)

    Changelog

    Added in version 0.14.

  property mimetype_params: Mapping[str, str]

    The mimetype parameters as dict. For example if the content type is `text/html; charset=utf-8` the params would be `{'charset': 'utf-8'}`.

    Changelog

    Added in version 0.14.

  property content_length: int | None

    The content length as integer. Reflected from and to the `headers`. Do not set if you set `files` or `form` for auto detection.

  property form: MultiDict[str, str]

    A `MultiDict` of form values.

  property files: FileMultiDict

    A `FileMultiDict` of uploaded files. Use `add_file()` to add new files.

  property input_stream: IO[bytes] | None

    An optional input stream. This is mutually exclusive with setting `form` and `files`, setting it will clear those. Do not provide this if the method is not `POST` or another method that has a body.

  property query_string: str

    The query string. If you set this to a string `args` will no longer be available.

  property args: MultiDict[str, str]

    The URL arguments as `MultiDict`.

  property server_name: str

    The server name (read-only, use `host` to set)

  property server_port: int

    The server port as integer (read-only, use `host` to set)

  close()

    Closes all files. If you put real `file` objects into the `files` dict you can call this method to automatically close them all in one go.

    Return type:

      None

  get_environ()

    Return the built environ.

    Changelog

    Changed in version 0.15: The content type and length headers are set based on input stream detection. Previously this only set the WSGI keys.

    Return type:

      WSGIEnvironment

  get_request(cls=None)

    Returns a request with the data. If the request class is not specified `request_class` is used.

    Parameters:

      cls (type[Request] | None) – The request wrapper to use.

    Return type:

      Request

werkzeug.test.create_environ(*args, **kwargs)

  Create a new WSGI environ dict based on the values passed. The first parameter should be the path of the request which defaults to ‘/’. The second one can either be an absolute path (in that case the host is localhost:80) or a full path to the request with scheme, netloc port and the path to the script.

  This accepts the same arguments as the `EnvironBuilder` constructor.

  Changelog

  Changed in version 0.5: This function is now a thin wrapper over `EnvironBuilder` which was added in 0.5. The `headers`, `environ_base`, `environ_overrides` and `charset` parameters were added.

  Parameters:

    - args (t.Any)

    - kwargs (t.Any)

  Return type:

    WSGIEnvironment

werkzeug.test.run_wsgi_app(app, environ, buffered=False)

  Return a tuple in the form (app_iter, status, headers) of the application output. This works best if you pass it an application that returns an iterator all the time.

  Sometimes applications may use the `write()` callable returned by the `start_response` function. This tries to resolve such edge cases automatically. But if you don’t get the expected output you should set `buffered` to `True` which enforces buffering.

  If passed an invalid WSGI application the behavior of this function is undefined. Never pass non-conforming WSGI applications to this function.

  Parameters:

    - app (WSGIApplication) – the application to execute.

    - buffered (bool) – set to `True` to enforce buffering.

    - environ (WSGIEnvironment)

  Returns:

    tuple in the form `(app_iter, status, headers)`

  Return type:

    tuple[t.Iterable[bytes], str, Headers]