Add method for getting associations by type.

A similar feature is used in bake & formhelper, I'm guessing we'll need
it again with the new ORM.

Cake/ORM/Associations.php

@@ -77,6 +77,18 @@ public function keys() {
 		return array_keys($this->_items);
 	}
 
+/**
+ * Get an array of associations matching a specific type.
+ *
+ * @return array
+ */
+	public function type($class) {
+		$out = array_filter($this->_items, function ($assoc) use ($class) {
+			return strpos(get_class($assoc), $class) !== false;
+		});
+		return array_values($out);
+	}
+
 /**
  * Drop/remove an association.
  *
@@ -85,7 +97,7 @@ public function keys() {
  * @param string The alias name.
  * @return void
  */
-	public function drop($alias) {
+	public function remove($alias) {
 		unset($this->_items[strtolower($alias)]);
 	}
 

Cake/Test/TestCase/ORM/AssociationsTest.php

@@ -39,7 +39,7 @@ public function setUp() {
  *
  * @return void
  */
-	public function testAddHasAndGet() {
+	public function testAddHasRemoveAndGet() {
 		$this->assertFalse($this->associations->has('users'));
 		$this->assertFalse($this->associations->has('Users'));
 
@@ -53,6 +53,39 @@ public function testAddHasAndGet() {
 
 		$this->assertSame($belongsTo, $this->associations->get('users'));
 		$this->assertSame($belongsTo, $this->associations->get('Users'));
+
+		$this->assertNull($this->associations->remove('Users'));
+
+		$this->assertFalse($this->associations->has('users'));
+		$this->assertFalse($this->associations->has('Users'));
+		$this->assertNull($this->associations->get('users'));
+		$this->assertNull($this->associations->get('Users'));
+	}
+
+/**
+ * Test keys()
+ *
+ * @return void
+ */
+	public function testKeys() {
+		$belongsTo = new BelongsTo([]);
+		$this->associations->add('Users', $belongsTo);
+		$this->associations->add('Categories', $belongsTo);
+		$this->assertEquals(['users', 'categories'], $this->associations->keys());
+
+		$this->associations->remove('Categories');
+		$this->assertEquals(['users'], $this->associations->keys());
+	}
+
+/**
+ * Test getting association names by type.
+ */
+	public function testType() {
+		$belongsTo = new BelongsTo([]);
+		$this->associations->add('Users', $belongsTo);
+
+		$this->assertSame([$belongsTo], $this->associations->type('BelongsTo'));
+		$this->assertSame([], $this->associations->type('HasMany'));
 	}
 
 /**