Correctly implementing support for NOT operator

lib/Cake/Model/Datasource/Database/Expression/QueryExpression.php

@@ -179,7 +179,7 @@ public function traverse($callable) {
 	}
 
 	protected function _addConditions(array $conditions, array $types) {
-		$operators = array('and', 'or', 'not', 'xor');
+		$operators = array('and', 'or', 'xor');
 
 		foreach ($conditions as $k => $c) {
 			$numericKey = is_numeric($k);
@@ -198,6 +198,11 @@ protected function _addConditions(array $conditions, array $types) {
 				continue;
 			}
 
+			if (strtolower($k) === 'not') {
+				$this->_conditions[] = new UnaryExpression(new self($c, $types), [], 'NOT');
+				continue;
+			}
+
 			if ($c instanceof QueryExpression && count($c) > 0) {
 				$this->_conditions[] = $c;
 				continue;

lib/Cake/Model/Datasource/Database/Expression/UnaryExpression.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace Cake\Model\Datasource\Database\Expression;
+
+class UnaryExpression extends QueryExpression {
+
+	public function sql() {
+		return $this->_conjunction . ' (' . ((string)current($this->_conditions)) . ')';
+	}
+
+}

lib/Cake/Test/TestCase/Model/Datasource/Database/QueryTest.php

@@ -808,4 +808,25 @@ public function testSelectExpressionComposition() {
 		$this->assertEquals(['id' => 1], $result->fetch('assoc'));
 		$this->assertEquals(['id' => 2], $result->fetch('assoc'));
 	}
+
+/**
+ * Tests that conditions can be nested with an unary operator using the array notation
+ *
+ * @return void
+ **/
+	public function testSelectWhereNot() {
+		$this->_insertDateRecords();
+		$query = new Query($this->connection);
+		$result = $query
+			->select(['id'])
+			->from('dates')
+			->where([
+				'not' => ['or' => ['id' => 1, 'id >' => 2], 'id' => 3]
+			])
+			->execute();
+		$this->assertCount(2, $result);
+		$this->assertEquals(['id' => 1], $result->fetch('assoc'));
+		$this->assertEquals(['id' => 2], $result->fetch('assoc'));
+	}
+
 }