Create Check_Runner interface

[mehulkaklotar]

Description

The Check Runner interface will be implemented by the specific context runner classes like AJAX runner or CLI runner. This interface will have access to the Checks class and its methods to run checks. The interface will have a run method that will be the responsibility of classes to implement to start the runner according to their context.

• Create CLI_Runner class #14
• Create AJAX_Runner class #15

Acceptance Criteria

• A new Check_Runner interface is created and exists at includes/Checker.
• The Check_Runner interface contains a public is_plugin_check() method.
  • The is_plugin_check method will return a boolean.
  • The method will be used to determine if the current request is intended for the plugin checker.
• The Check_Runner interface contains a public prepare() method.
  • The prepare() method will be used to run any universal preparations depending on the checks requested.
• The Check_Runner interface contains a public run() method.
  • The run method returns an instance of the Check_Results class.
  • The method will run the requested checks against the plugin context and return the results.

[felixarntz]

@jjgrainger Can you outline what the runner method will work in its two implementations for CLI and AJAX? Is having a single method sufficient? For example, in the AJAX approach, we'll need to run individual checks per AJAX request. How would the AJAX_Runner do that if it only has a single runner method that has no context of which checks have been run already or which one should be run next?

I think this interface needs a lot more thought on how it should be implemented, to be able to cover both CLI and AJAX. CLI is a lot simpler, so we should probably look at AJAX to come up with a solid approach. We also need to think about how we can express the common parts between them in separate methods. If there's any functionality that's truly shared, we may benefit from an abstract base class implementing this interface too (not saying that we do, but maybe).

Last but not least, why is the method called runner? Methods should typically be action-based, runner is a noun.