Selenium Wire

Selenium Wire extends Selenium's Python bindings to give your tests access to the underlying requests made by the browser. It is a lightweight library designed for ease of use with minimal external dependencies.

With Selenium Wire, you author your tests in just the same way as you do with Selenium, but you get an additional user-friendly API for accessing things such as the request/response headers, status code and body content.

Simple Example

from seleniumwire import webdriver  # Import from seleniumwire

# Create a new instance of the Firefox driver
driver = webdriver.Firefox()

# Go to the Google home page
driver.get('https://www.google.com')

# Access requests via the `requests` attribute
for request in driver.requests:
    if request.response:
        print(
            request.path,
            request.response.status_code,
            request.response.headers['Content-Type']
        )

Prints:

https://www.google.com/ 200 text/html; charset=UTF-8
https://www.google.com/images/branding/googlelogo/2x/googlelogo_color_120x44dp.png 200 image/png
https://consent.google.com/status?continue=https://www.google.com&pc=s&timestamp=1531511954&gl=GB 204 text/html; charset=utf-8
https://www.google.com/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png 200 image/png
https://ssl.gstatic.com/gb/images/i2_2ec824b0.png 200 image/png
https://www.google.com/gen_204?s=webaft&t=aft&atyp=csi&ei=kgRJW7DBONKTlwTK77wQ&rt=wsrt.366,aft.58,prt.58 204 text/html; charset=UTF-8
...

Features

Straightforward, user-friendly API
All HTTP/HTTPS requests captured
Access to request/response bodies
Modify responses
Header injection/filtering
URL rewriting
Proxy server support

Compatibilty

Python 3.4+
Selenium 3.4.0+
Firefox, Chrome, Safari and Edge are supported

Installation
- OpenSSL
- Browser Setup
Usage
Request Attributes
Response Attributes
Modifying Requests
- Modifying Headers
- Rewriting URLs
Proxies
Other Options
Limitations
License

Installation

Install using pip:

pip install selenium-wire

OpenSSL

Selenium Wire requires OpenSSL for capturing HTTPS requests.

Linux

# For apt based Linux systems
sudo apt install openssl

# For RPM based Linux systems
sudo yum install openssl

MacOS

brew install openssl

Windows

No installation is required. OpenSSL for Windows is bundled with Selenium Wire.

Browser Setup

Firefox and Chrome

No specific configuration should be necessary - everything should just work.

You will however need to ensure that you have downloaded the Gecko driver and Chrome driver for Firefox and Chrome to be remotely controlled - the same as if you were using Selenium directly. Once downloaded, these executables should be placed somewhere on the system path.

Safari

There are a few manual steps that have to be carried out before you can use Safari with Selenium Wire.

Edge

Like Safari, Microsoft Edge requires some manual configuration before it can be used with Selenium Wire.

Usage

Ensure that you import webdriver from the seleniumwire package:

from seleniumwire import webdriver

For sub-packages of webdriver, you should continue to import these directly from selenium. For example, to import WebDriverWait:

# Sub-packages of webdriver must still be imported from `selenium` itself
from selenium.webdriver.support.ui import WebDriverWait

Creating the Webdriver

For Firefox and Chrome, you don't need to do anything special. Just instantiate the webdriver as you would normally, passing in Selenium specific options if you have any. Selenium Wire also has it's own options that can be passed in the seleniumwire_options attribute.

Firefox

driver = webdriver.Firefox()

Chrome

driver = webdriver.Chrome()

Safari

For Safari, you need to tell Selenium Wire the port number you selected when you configured the browser in Browser Setup. For example, if you chose port 12345, then you would pass it in the seleniumwire_options like this:

driver = webdriver.Safari(seleniumwire_options={'port': 12345})

Edge

For Edge, you need to tell Selenium Wire the port number you selected when you configured the browser in Browser Setup. For example, if you chose port 12345, then you would pass it in the seleniumwire_options like this:

driver = webdriver.Edge(seleniumwire_options={'port': 12345})

Using Self-Signed Certificates

If the site you are testing uses a self-signed certificate then you must set the verify_ssl option to False in the seleniumwire_options:

driver = webdriver.Firefox(seleniumwire_options={'verify_ssl': False})

This this will need to be done regardless of the type of browser you are using.

Accessing Requests

Selenium Wire captures all HTTP/HTTPS traffic made by the browser during a test.

driver.requests

You can retrieve all requests with the driver.requests attribute. The requests are just a list and can be iterated (like in the opening example) and indexed:

first_request = driver.requests[0]

driver.last_request

The list of requests held by driver.requests is in chronological order. If you want to access the most recent request, use the dedicated driver.last_request attribute:

last_request = driver.last_request

This is more efficient than using driver.requests[-1].

Waiting for a Request

When you ask for captured requests using driver.requests or driver.last_request you have to be sure that the requests you're interested in have actually been captured. If you ask too soon, then you may find that a request is not yet present, or is present but has no associated response.

driver.wait_for_request()

This method will wait for a previous request with a specific path to complete before allowing the test to continue. The path can be a unique part of the URL or the full URL itself.

For example, to wait for an AJAX request to return after a button is clicked:

# Click a button that triggers a background request to https://server/api/products/12345/
button_element.click()

# Wait for the request/response to complete
request = driver.wait_for_request('/api/products/12345/')

Note that driver.wait_for_request() doesn't make a request, it just waits for a previous request made by some other action.

The wait_for_request() method will return the first fully completed request it finds that matches the supplied path. Fully completed meaning that the response must have returned. The method will wait up to 10 seconds by default but you can vary that with the timeout argument:

# Wait up to 30 seconds for a request/response
request = driver.wait_for_request('/api/products/12345/', timeout=30)

If a fully completed request is not seen within the timeout period a TimeoutException is raised.

Clearing Requests

To clear previously captured requests, use del:

del driver.requests

Scoping Request Capture

By default, Selenium Wire will capture all requests the browser makes during a test. You may want to restrict this to particular URLs - e.g. for performance reasons.

To restrict request capture use the scopes attribute. This accepts a list of regular expressions that will match URLs to be captured.

driver.scopes = [
    '.*stackoverflow.*',
    '.*github.*'
]

# Only request URLs containing "stackoverflow" or "github" will now be captured...

Request Attributes

Requests have the following attributes.

method: The HTTP method type such as GET or POST.
path: The request path.
headers: A case-insensitive dictionary of request headers. Asking for request.headers['user-agent'] will return the value of the User-Agent header.
body: The request body as bytes. If the request has no body the value of body will be None.
response: The response associated with the request. This will be None if the request has no response.

Response Attributes

The response can be retrieved from a request via the response attribute. A response may be None if it was never captured, which may happen if you asked for it before it returned or if the server timed out etc. A response has the following attributes.

status_code: The status code of the response such as 200 or 404.
reason: The reason phrase such as OK or Not Found.
headers: A case-insensitive dictionary of response headers. Asking for response.headers['content-length'] will return the value of the Content-Length header.
body: The response body as bytes. If the response has no body the value of body will be None.

Modifying Requests

Selenium Wire allows you to modify the request headers the browser sends as well as rewrite any part of the request URL.

Modifying Headers

The driver.header_overrides attribute is used for modifying headers.

To add one or more new headers to a request, create a dictionary containing those headers and set it as the value of header_overrides.

driver.header_overrides = {
    'New-Header1': 'Some Value',
    'New-Header2': 'Some Value'
}

# All subsequent requests will now contain New-Header1 and New-Header2

If a header already exists in a request it will be overwritten by the one in the dictionary. Header names are case-insensitive.

To filter out one or more headers from a request, set the value of those headers to None.

driver.header_overrides = {
    'Existing-Header1': None,
    'Existing-Header2': None
}

# All subsequent requests will now *not* contain Existing-Header1 or Existing-Header2

To clear the header overrides that you have set, use del:

del driver.header_overrides

Header overrides can also be applied on a per-URL basis, in the following format:

driver.header_overrides = [
    ('.*prod1.server.com.*', {'User-Agent': 'Test_User_Agent_String',
                              'New-Header': 'HeaderValue'}),
    ('.*prod2.server.com.*', {'User-Agent2': 'Test_User_Agent_String2',
                              'New-Header2': 'HeaderValue'})
]

# Only requests to prod1.server.com or prod2.server.com will have their headers modified

Rewriting URLs

The driver.rewrite_rules attribute is used for rewriting request URLs.

Each rewrite rule should be specified as a 2-tuple or list, the first element containing the URL pattern to match and the second element the replacement. One or more rewrite rules can be supplied.

driver.rewrite_rules = [
    (r'(https?://)prod1.server.com(.*)', r'\1prod2.server.com\2'),
]

# All subsequent requests that match http://prod1.server.com... or https://prod1.server.com...
# will be rewritten to http://prod2.server.com... or https://prod2.server.com...

The match and replacement syntax is just Python's regex syntax. See re.sub for more information.

To clear the rewrite rules that you have set, use del:

del driver.rewrite_rules

Proxies

Selenium Wire captures requests by using its own proxy server under the covers. This means you cannot use the webdriver's DesiredCapabilities API to configure your own proxy, like you might when using Selenium directly.

If the site you are testing sits behind a proxy server you can tell Selenium Wire about that proxy server in the options you pass to the webdriver instance. The configuration takes the following format:

options = {
    'proxy': {
        'http': 'http://username:password@host:port',
        'https': 'https://username:password@host:port',
        'no_proxy': 'localhost,127.0.0.1,dev_server:8080'
    }
}
driver = webdriver.Firefox(seleniumwire_options=options)

The username and password are optional and can be specified when a proxy server requires authentication. Basic authentication is assumed by default.

The proxy configuration can also be loaded through environment variables called http, https and no_proxy. The proxy configuration in the options passed to the webdriver instance will take precedence over environment variable configuration if both are specified.

Proxy authentication other than Basic

Basic authentication is used by default when supplying a username and password in the URL. If you are connecting to an upstream proxy server that uses an authentication scheme different to Basic, then you can supply the full value for the Proxy-Authorization header using the custom_authorization option. For example, if your proxy used the Bearer scheme:

options = {
    'proxy': {
        'http': 'http://host:port',
        'https': 'https://host:port',
        'no_proxy': 'localhost,127.0.0.1,dev_server:8080',
        'custom_authorization': 'Bearer mytoken123'  # Custom Proxy-Authorization header value
    }
}
driver = webdriver.Firefox(seleniumwire_options=options)

Other Options

Other options that can be passed to Selenium Wire via the seleniumwire_options webdriver attribute:

connection_timeout: The number of seconds Selenium Wire should wait before timing out requests. The default is 5 seconds. Increase this value if you're working with a slow server that needs more time to respond. Set to None for no timeout.

options = {
    'connection_timeout': None  # Never timeout
}
driver = webdriver.Firefox(seleniumwire_options=options)

custom_response_handler: This function that should be passed in custom response handlers should maintain a signature that it compatible with CaptureRequestHandler.response_handler, as all arguments passed to that function will in turn be passed to your function. In order to modify the response data, you will need to return it from your function (the response data for the request is given in the res_body argument).

def custom(req, req_body, res, res_body):
    print(f'res_body length: {len(res_body)}')

options = {
    'custom_response_handler': custom
}
drv = webdriver.Firefox(seleniumwire_options=options)
drv.get('https://example.com')

The code above will print something like this to the console (loading a page will almost always initiate more than one request):

res_body length: 471
res_body length: 606

ignore_http_methods: A list of HTTP methods (specified as uppercase strings) that should be ignored by Selenium Wire and not captured. The default is ['OPTIONS'] which ignores all OPTIONS requests. To capture all request methods, set ignore_http_methods to an empty list:

options = {
    'ignore_http_methods': []  # Capture all requests, including OPTIONS requests
}
driver = webdriver.Firefox(seleniumwire_options=options)

disable_encoding: Whether to disable content encoding. When set to True, the Accept-Encoding header will be set to identity for all requests. This tells the server to not compress/modify the response. The default is False.

options = {
    'disable_encoding': True  # Tell the server not to compress the response
}
driver = webdriver.Firefox(seleniumwire_options=options)

suppress_connection_errors: Whether to suppress connection related tracebacks. The default is True so that harmless errors that commonly occur at browser shutdown do not alarm users. When suppressed, the connection error message is logged at DEBUG level without a traceback. Set to False to allow exception propagation and see full tracebacks.

options = {
    'suppress_connection_errors': False  # Show full tracebacks for any connection errors
}
driver = webdriver.Firefox(seleniumwire_options=options)

Limitations

Selenium Wire will currently work with tests that run on the same machine as the browser. A distributed setup using Selenium Grid is not yet supported.
Sites that use NTLM authentication (Windows authentication) cannot currently be tested with Selenium Wire. NTLM authentication is not supported.

License

MIT

HankLu-2019/selenium-wire