wdspec tests¶
The term “wdspec” describes a type of test in WPT which verifies some aspect of the WebDriver protocol. These tests are written in the Python programming language and structured with the pytest testing framework.
The test files are organized into subdirectories based on the WebDriver
command under test. For example, tests for the Close Window
command are located in then
close_window
directory.
Similar to testharness.js tests, wdspec tests contain within
them any number of “sub-tests.” Sub-tests are defined as Python functions whose
name begins with test_
, e.g. test_stale_element
.
The webdriver
client library¶
web-platform-tests maintains a WebDriver client library called webdriver
located in the tools/webdriver/
directory. Like other client libraries, it
makes it easier to write code which interfaces with a browser using the
protocol.
Many tests require some “set up” code–logic intended to bring the browser to a
known state from which the expected behavior can be verified. The convenience
methods in the webdriver
library should be used to perform this task
because they reduce duplication.
However, the same methods should not be used to issue the command under test. Instead, the HTTP request describing the command should be sent directly. This practice promotes the descriptive quality of the tests and limits indirection that tends to obfuscate test failures.
Here is an example of a test for the Element Click command:
from tests.support.asserts import assert_success
def test_null_response_value(session, inline):
# The high-level API is used to set up a document and locate a click target
session.url = inline("<p>foo")
element = session.find.css("p", all=False)
# An HTTP request is explicitly constructed for the "click" command itself
response = session.transport.send(
"POST", "session/{session_id}/element/{element_id}/click".format(
session_id=session.session_id,
element_id=element.id))
assert_success(response)
Utility functions¶
The wedbdriver
library is minimal by design. It mimics the structure of the
WebDriver specification. Many conformance tests perform similar operations
(e.g. calculating the center point of an element or creating a document), but
the library does not expose methods to facilitate them. Instead, wdspec tests
define shared functionality in the form of “support” files.
Many of these functions are intended to be used directly from the tests using
Python’s built-in import
keyword. Others (particularly those that operate on
a WebDriver session) are defined in terms of Pytest “fixtures” and must be
loaded accordingly. For more detail on how to define and use test fixtures,
please refer to the pytest project’s documentation on the
topic.