AnyInstance matcher for expectHookAdded

[BrianHenryIE]

Problem:

Currently WP_Mock needs a reference to an object instance for expectHookAdded to work. A common pattern where this is a problem is where the actions and filters are added during object construction.

class Problem {
	public function __construct() {
		add_filter( 'init', array( $this, 'on_init' ) );
	}
	public function on_init(){	
	}
}

class Similarly {
	public function on_init(){
	}
}
function go() {
	$similarly = new Similarly();
	add_filter( 'init', array( $similarly, 'on_init' ) );
}
go();

The problem is described in #8, #80, #93, #127, #143.

Solution:

Add a matcher like WP_Mock::fuzzyObject() – AnyInstance().

Allowing:

\WP_Mock::expectActionAdded( 'init', array( new AnyInstance( Problem::class ), 'on_init' ) );

This is basically the solution proposed in #12 .

I have this working in my own fork: Add AnyInstance matcher.

And can be tested with:

{
    "require-dev": {
        "10up/wp_mock": "0.4.2",
        "cweagans/composer-patches": "*"
    },
    "extra": {
        "patches": {
            "10up/wp_mock": {
                "Add AnyObject matcher": "https://github.com/BrianHenryIE/wp_mock/pull/1.patch"
            }
        }
    }
}

Describe alternatives you've considered

The general advice has been to separate object construction and adding hooks. This is fine, but the solution to this is easy and is coherent with WP_Mock.

I tried adding the functionality into FuzzyObject but became uncertain of side-effects. It may be possible, and preferable. The current code is a straightforward proof of concept – I expect suggestions and alterations before any PR.