WP Helper functions - doing_*(): ensure parameter defaults are in line with WP Core

The underlying `HookRunningStack::has()` method already allowed for a `$hook_name` being `null`, but the wrapping functions which called the method did not.

Fixed now.

Includes tests.
Includes fixing the documentation.

Refs:
* https://developer.wordpress.org/reference/functions/doing_action/
* https://developer.wordpress.org/reference/functions/doing_filter/

Author: jrfnl

inc/api.php

@@ -273,10 +273,10 @@ function did($action)
      *
      * Brain Monkey version of `doing_action` will alias here.
      *
-     * @param string $action
+     * @param string|null $action
      * @return bool
      */
-    function doing($action)
+    function doing($action = null)
     {
         return Container::instance()
                         ->hookRunningStack()
@@ -380,10 +380,10 @@ function applied($filter)
      *
      * Brain Monkey version of `doing_filter` will alias here.
      *
-     * @param string $filter
+     * @param string|null $filter
      * @return bool
      */
-    function doing($filter)
+    function doing($filter = null)
     {
         return Container::instance()
                         ->hookRunningStack()

inc/wp-hook-functions.php

@@ -143,14 +143,14 @@ function remove_filter($hook_name, $callback, $priority = 10)
 }
 
 if ( ! function_exists('doing_action')) {
-    function doing_action($hook_name)
+    function doing_action($hook_name = null)
     {
         return Monkey\Actions\doing($hook_name);
     }
 }
 
 if ( ! function_exists('doing_filter')) {
-    function doing_filter($hook_name)
+    function doing_filter($hook_name = null)
     {
         return Monkey\Filters\doing($hook_name);
     }

src/Hook/HookRunningStack.php

@@ -52,7 +52,7 @@ public function last()
     }
 
     /**
-     * @param string $hook_name
+     * @param string|null $hook_name
      * @return bool
      */
     public function has($hook_name = null)

tests/cases/unit/Api/ApplyFiltersTest.php

@@ -227,6 +227,8 @@ public function testNestedFiltersAndDoingFilter()
         Filters\expectApplied('first_level')->once()->andReturnUsing(function ($arg) {
 
             static::assertTrue(current_filter() === 'first_level');
+            static::assertTrue(doing_filter(), 'doing_filter() without hook name doesn\'t work (in first level)');
+            static::assertTrue(doing_filter(null), 'doing_filter() with null hook name doesn\'t work (in first level)');
             static::assertTrue(doing_filter('first_level'));
             static::assertFalse(doing_filter('second_level'));
 
@@ -237,6 +239,7 @@ public function testNestedFiltersAndDoingFilter()
 
             static::assertSame('How is Monkey?', $arg);
             static::assertTrue(current_filter() === 'second_level');
+            static::assertTrue(doing_filter(), 'doing_filter() without hook name doesn\'t work (in second level)');
             static::assertTrue(doing_filter('first_level'));
             static::assertTrue(doing_filter('second_level'));
 
@@ -245,6 +248,8 @@ public function testNestedFiltersAndDoingFilter()
 
 
         static::assertSame('Monkey is great!', apply_filters('first_level', 'How is Monkey?'));
+        static::assertFalse(doing_filter(), 'doing_filter() without hook name doesn\'t work (in outer code)');
+        static::assertFalse(doing_filter(null), 'doing_filter() with null hook name doesn\'t work (in outer code)');
         static::assertFalse(doing_filter('first_level'));
         static::assertFalse(doing_filter('second_level'));
     }

tests/cases/unit/Api/DoActionTest.php

@@ -116,12 +116,15 @@ public function testNestedDoWithExpectationWhenHappenDoingAction()
         Actions\expectDone('first_level')->once()->whenHappen(function () {
             do_action('second_level', 'Catch me!');
             do_action('second_level', 'Catch me!');
+            static::assertTrue(doing_action('first_level'));
         });
 
         Actions\expectDone('second_level')->twice()->whenHappen(function ($arg) {
 
             static::assertSame('Catch me!', $arg);
             static::assertTrue(current_filter() === 'second_level');
+            static::assertTrue(doing_action(), 'doing_action() without hook name doesn\'t work (in second level)');
+            static::assertTrue(doing_action(null), 'doing_action() with null hook name doesn\'t work (in second level)');
             static::assertTrue(doing_action('first_level'));
             static::assertTrue(doing_action('second_level'));
             // Checking for output will ensure above assertions have ran.
@@ -132,6 +135,7 @@ public function testNestedDoWithExpectationWhenHappenDoingAction()
 
         do_action('first_level');
 
+        static::assertFalse(doing_action(), 'doing_action() without hook name doesn\'t work (in outer code)');
         static::assertFalse(doing_action('first_level'));
         static::assertFalse(doing_action('second_level'));
     }