CheezTest

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CheezTest lets you create and run Batcache-compatible server-side A/B tests in your theme.

A joint LOL by the fine folks I Can Has Cheezburger (http://www.cheezburger.com) and Automattic (http://automattic.com)

Main class from which all A/B tests are inherited. Enables fast setup of A/B tests - upon initialization, the basic order of execution is: set test name > check if user is qualified to participate > check if user has been assigned a segment, and assign if not > assign user to group > execute 'action' callback if present.

User's qualification, segment, and group tests are done in batcache so as to ensure correct cache variants are served.

User's segment is assigned server-side via magic. Mutliple test segments are assigned at once - so if a user is qualified to participate in more than one test, all segments are assigned at the same time. When segments need to be set, a small javascript is injected into the via a call to CheezTest::write_segment_cookie(). This javascript sets a cookie to retain the segment assigned earlier.

Test case data (name, is_qualified, & group) are stored in the $active_tests static hash and made accessible via the 'is_qualified_for', 'get_group_for', and 'is_in_group' static methods. This enables theme branching via:

if ( CheezTest::is_qualified_for( 'my-example-test' ) { //test-specific stuff goes here }

• or -

if ( CheezTest::is_in_group( 'my-example-test', 'my-example-group' ) ) { //group-specific stuff goes here }

The plugin makes use of Batcache’s support for vary_cache_on_function, which saves page variants in a page’s cache and then evaluates which one to serve when the page loads.

IMPORTANT: Since the tests run before Batcache, which in turn runs very early (before theme code is included), only built-in PHP functions and jetpack_is_mobile() can be used when defining tests. Any theme-specific functions will not be available.