servo/tests/wpt/web-platform-tests/docs/_writing-tests/server-features.md

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page	Server Features	12

Advanced Testing Features

Certain test scenarios require more than just static HTML generation. This is supported through the wptserve server. Several scenarios in particular are common:

Tests Involving Multiple Origins

In the test environment, five subdomains are available: www, www1, www2, 天気の良い日, and élève; there is also nonexistent-origin which is guaranteed not to resolve. In addition, the HTTP server listens on two ports, and the WebSockets server on one. These subdomains and ports must be used for cross-origin tests. Tests must not hardcode the hostname of the server that they expect to be running on or the port numbers, as these are not guaranteed by the test environment. Instead they can get this information in one of two ways:

• From script, using the location API.

• By using a textual substitution feature of the server.

In order for the latter to work, a file must either have a name of the form {name}.sub.{ext} e.g. example-test.sub.html or be referenced through a URL containing pipe=sub in the query string e.g. example-test.html?pipe=sub. The substitution syntax uses {% raw %}{{ }}{% endraw %} to delimit items for substitution. For example to substitute in the host name on which the tests are running, one would write: {% raw %}{{host}}{% endraw %}.

As well as the host, one can get full domains, including subdomains using the domains dictionary. For example, {% raw %}{{domains[www]}}{% endraw %} or {% raw %}{{domains[élève]}}{% endraw %} would be replaced by the full qualified domain name of the respective subdomains.

Ports are also available on a per-protocol basis. For example, {% raw %}{{ports[ws][0]}}{% endraw %} is replaced with the first (and only) WebSockets port, while {% raw %}{{ports[http][1]}}{% endraw %} is replaced with the second HTTP port.

The request URL itself can be used as part of the substitution using the location dictionary, which has entries matching the window.location API. For example, {% raw %}{{location[host]}}{% endraw %}is replaced by hostname:port for the current request, matching location.host.

Tests Requiring Special Headers

For tests requiring that a certain HTTP header is set to some static value, a file with the same path as the test file except for an an additional .headers suffix may be created. For example for /example/test.html, the headers file would be /example/test.html.headers. This file consists of lines of the form

header-name: header-value

For example

Content-Type: text/html; charset=big5

To apply the same headers to all files in a directory use a __dir__.headers file. This will only apply to the immediate directory and not subdirectories.

Headers files may be used in combination with substitutions by naming the file e.g. test.html.sub.headers.

Tests Requiring Full Control Over The HTTP Response

For full control over the request and response the server provides the ability to write .asis files; these are served as literal HTTP responses. It also provides the ability to write Python scripts that have access to request data and can manipulate the content and timing of the response. For details see the wptserve documentation.