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
• Header injection/filtering
• URL rewriting
• Proxy server support

Compatibilty

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

Table of Contents

• Installation
  • OpenSSL
  • Browser Setup
• Usage
  • Accessing Requests
  • Waiting for a Request
  • Clearing Requests
• Request Attributes
• Response Attributes
• Modifying Requests
  • Modifying Headers
  • Rewriting URLs
• Proxies
• 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 ought to 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.

1. You must allow Safari to be remotely controlled by selecting "Allow Remote Automation" from Safari's "Develop" menu.
2. You must install Selenium Wire's root certificate into your Mac's keystore by following these steps:
   • First extract the certificate with python -m seleniumwire extractcert. You should see a file called ca.crt in your current working directory.
   • Now open your Mac's Keychain Access utility (located in Applications > Utilities).
   • From the "File" menu, select "Import Items".
   • Browse to the ca.crt file you just extracted and import it.
   • Click on "Certificates" in the left hand side of the Key Chain Access utility and you should now see the Selenium Wire CA certificate listed.
   • Double-click the certificate in the right hand pane to open its properties.
   • At the top of the properties window that opens, expand the "Trust" section and select "Always Trust" in the top drop down menu.
   • Close the properties window (you may be prompted to enter your password).
   • Quit the Keychain Access utility.
3. You need to tell Safari to use a proxy server for its HTTP and HTTPS traffic.
   • From Safari's "Safari" menu, open "Preferences".
   • Click the "Advanced" tab at the top.
   • Click the "Change Settings..." button for the "Proxies" option.
   • Check the "Web Proxy (HTTP)" checkbox and enter "localhost" in the server box, and a port (e.g. 12345) in the box next to it.
   • Check the "Secure Web Proxy (HTTPS)" checkbox and repeat the previous step for server and port.
   • Click "OK" on the proxies window, and then "Apply" on the network window before closing it.

Edge

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

1. You must install Microsoft's WebDriver so that Edge can be remotely controlled - the same as if you were using Selenium directly.
2. You must install Selenium Wire's root certificate into your PC's certificate store by following these steps:
   • First extract the certificate with python -m seleniumwire extractcert. You should see a file called ca.crt in your current working directory.
   • Open Internet Options (you can search for it using Cortana on Windows 10).
   • Click the "Content" tab and then the "Certificates" button.
   • Press the "Import..." button to open the Certificate Import Wizard, then press "Next".
   • Browse to the ca.crt you just extracted and press "Next".
   • Select the "Place all certficates in the following store" option and browse to "Trusted Root Certification Authorities", press "OK" and then "Next".
   • Press "Finish" on the final screen of the wizard, and then "OK" on all open windows.
3. You need to tell Edge to use a proxy server for its HTTP and HTTPS traffic.
   • Open Internet Options (you can search for it from the Windows 10 start menu).
   • Click the "Connections" tab and then the "LAN settings" button.
   • Tick the box that says "Use a proxy server for your LAN...".
   • In the "Address" box enter "localhost" and in the "Port" box a port number (e.g. 12345).
   • Click "OK" and then "OK" on the Internet Options window.

Usage

Ensure that you import webdriver from the seleniumwire package:

from seleniumwire import webdriver

For sub-packages of webdriver, you can 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

Then it's just a matter of creating a new driver instance.

For Firefox and Chrome, you don't need to pass any Selenium Wire specific options (you can still pass any of your own webdriver specific options however).

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 like this:

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

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 like this:

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

Accessing Requests

Selenium Wire captures all HTTP/HTTPS traffic made by the browser during a test. Accessing captured requests is straightforward.

You can retrieve all requests with the driver.requests attribute.

all_requests = driver.requests

The requests are just a list and can be iterated (like in the opening example) and indexed:

first_request = driver.requests[0]

The list of 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.

Using implicit or explicit waits

One way to achieve this is to use Selenium's existing implicit or explicit waits to wait for the DOM to change. For example:

# Click a button that triggers a background request
button_element.click()

# Wait for an element to appear, implying request complete
element = WebDriverWait(driver, 10).until(EC.presence_of_element_located((By.ID, "some-element")))

# Now check the completed request
assert driver.last_request.response.status_code == 200

Using driver.wait_for_request()

Alternatively, Selenium Wire provides driver.wait_for_request(). This method will wait for a previous request with a specific path to complete before allowing the test to continue.

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.

The wait_for_request() method does a substring match on the path so you can pass just the part that uniquely identifies the request:

# Pass just the unique part of the path
request = driver.wait_for_request('/12345/')

Or alternatively you can pass the full URL itself:

# Match the full URL
request = driver.wait_for_request('https://server/api/products/12345/')

Clearing Requests

To clear previously captured requests, just use del:

del driver.requests

This can be useful if you're only interested in capturing requests that occur when a specific action is performed, for example, the AJAX requests associated with a button click. In this case you can clear out any previous requests with del before you click the button.

Request Attributes

Requests that you retrieve using driver.requests or one of the other mechanisms 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 as 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, just use del:

del driver.header_overrides

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, just 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 for the proxy server should be specified as a URL in the format http://username:password@server:port. The username and password are optional and can be specified when a proxy server requires authentication.

You can configure a proxy for the http and https protocols and optionally set a value for no_proxy - which should be a comma separated list of hostnames where the proxy should be bypassed. For example:

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 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.

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