Make unlink() return true.

Having this method return true allows it to be used in conditionals.
While it never returns false naturally, returning true makes this method
more consistent with other methods like link() and replaceLinks().

Refs #9208

src/ORM/Association/BelongsToMany.php

@@ -709,12 +709,12 @@ class BelongsToMany extends Association
      * `$article->get('tags')` will contain all tags in `$newTags` after liking
      *
      * @param \Cake\Datasource\EntityInterface $sourceEntity the row belonging to the `source` side
-     * of this association
+     *   of this association
      * @param array $targetEntities list of entities belonging to the `target` side
-     * of this association
+     *   of this association
      * @param array $options list of options to be passed to the internal `save` call
      * @throws \InvalidArgumentException when any of the values in $targetEntities is
-     * detected to not be already persisted
+     *   detected to not be already persisted
      * @return bool true on success, false otherwise
      */
     public function link(EntityInterface $sourceEntity, array $targetEntities, array $options = [])
@@ -759,14 +759,14 @@ class BelongsToMany extends Association
      * `$article->get('tags')` will contain only `[$tag4]` after deleting in the database
      *
      * @param \Cake\Datasource\EntityInterface $sourceEntity an entity persisted in the source table for
-     * this association
+     *   this association
      * @param array $targetEntities list of entities persisted in the target table for
-     * this association
+     *   this association
      * @param array|bool $options list of options to be passed to the internal `delete` call,
-     * or a `boolean`
+     *   or a `boolean`
      * @throws \InvalidArgumentException if non persisted entities are passed or if
-     * any of them is lacking a primary key value
-     * @return void
+     *   any of them is lacking a primary key value
+     * @return bool Success
      */
     public function unlink(EntityInterface $sourceEntity, array $targetEntities, $options = [])
     {
@@ -792,7 +792,7 @@ class BelongsToMany extends Association
 
         $existing = $sourceEntity->get($property) ?: [];
         if (!$options['cleanProperty'] || empty($existing)) {
-            return;
+            return true;
         }
 
         $storage = new SplObjectStorage;
@@ -808,6 +808,7 @@ class BelongsToMany extends Association
 
         $sourceEntity->set($property, array_values($existing));
         $sourceEntity->dirty($property, false);
+        return true;
     }
 
     /**
@@ -991,12 +992,12 @@ class BelongsToMany extends Association
      * `$article->get('tags')` will contain only `[$tag1, $tag3]` at the end
      *
      * @param \Cake\Datasource\EntityInterface $sourceEntity an entity persisted in the source table for
-     * this association
+     *   this association
      * @param array $targetEntities list of entities from the target table to be linked
      * @param array $options list of options to be passed to the internal `save`/`delete` calls
-     * when persisting/updating new links, or deleting existing ones
+     *   when persisting/updating new links, or deleting existing ones
      * @throws \InvalidArgumentException if non persisted entities are passed or if
-     * any of them is lacking a primary key value
+     *   any of them is lacking a primary key value
      * @return bool success
      */
     public function replaceLinks(EntityInterface $sourceEntity, array $targetEntities, array $options = [])

tests/TestCase/ORM/Association/BelongsToManyTest.php

@@ -518,7 +518,7 @@ class BelongsToManyTest extends TestCase
         $initial = $entity->tags;
         $this->assertCount(1, $initial);
 
-        $assoc->unlink($entity, $entity->tags);
+        $this->assertTrue($assoc->unlink($entity, $entity->tags));
         $this->assertEmpty($entity->get('tags'), 'Property should be empty');
 
         $new = $articles->get(2, ['contain' => 'Tags']);
@@ -549,7 +549,7 @@ class BelongsToManyTest extends TestCase
         $initial = $entity->tags;
         $this->assertCount(1, $initial);
 
-        $assoc->unlink($entity, $initial, ['cleanProperty' => false]);
+        $this->assertTrue($assoc->unlink($entity, $initial, ['cleanProperty' => false]));
         $this->assertNotEmpty($entity->get('tags'), 'Property should not be empty');
         $this->assertEquals($initial, $entity->get('tags'), 'Property should be untouched');