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 @@ protected function _saveLinks(EntityInterface $sourceEntity, $targetEntities, $o
      * `$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 $options = [])
@@ -759,14 +759,14 @@ function () use ($sourceEntity, $targetEntities, $options) {
      * `$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, $options = [])
     {
@@ -792,7 +792,7 @@ function () use ($sourceEntity, $targetEntities, $options) {
 
         $existing = $sourceEntity->get($property) ?: [];
         if (!$options['cleanProperty'] || empty($existing)) {
-            return;
+            return true;
         }
 
         $storage = new SplObjectStorage;
@@ -808,6 +808,7 @@ function () use ($sourceEntity, $targetEntities, $options) {
 
         $sourceEntity->set($property, array_values($existing));
         $sourceEntity->dirty($property, false);
+        return true;
     }
 
     /**
@@ -991,12 +992,12 @@ protected function _appendJunctionJoin($query, $conditions)
      * `$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 @@ public function testUnlinkSuccess()
         $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 @@ public function testUnlinkWithoutPropertyClean()
         $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');