Fix COUNT(*) with group by operations.

Both group by and mapReduce should work with count.

Cake/ORM/Query.php

@@ -620,17 +620,23 @@ public function first() {
 /**
  * Return the COUNT(*) for for the query.
  *
- * This method will replace the selected fields with a COUNT(*)
- * erase any configured mapReduce functions and execute the query
- * returning the number of rows.
+ * If the query does not contain GROUP BY or map reduce functions, then
+ * this method will replace the selected fields with a COUNT(*), and the resulting
+ * count will be returned.
+ *
+ * If the query does contain GROUP BY or map reduce functions, then it
+ * will be executed, and the number of rows in the ResultSet will be returned.
  *
  * @return integer
  */
 	public function count() {
-		$query = $this->select(['count' => $this->func()->count('*')], true)
-			->hydrate(false);
-		$query->mapReduce(null, null, true);
-		return $query->first()['count'];
+		if ($this->clause('group') === [] && $this->mapReduce() === []) {
+			$this->select(['count' => $this->func()->count('*')], true)
+				->hydrate(false);
+			return $this->first()['count'];
+		}
+		$results = $this->execute();
+		return count($results);
 	}
 
 /**

Cake/Test/TestCase/ORM/QueryTest.php

@@ -1403,4 +1403,15 @@ public function testCount() {
 		$this->assertEquals(['count' => 2], $result->one());
 	}
 
+/**
+ * Test that count() returns correct results with group by.
+ */
+	public function testCountWithGroup() {
+		$table = TableRegistry::get('articles');
+		$query = $table->find('all')
+			->group(['published']);
+		$result = $query->count();
+		$this->assertEquals(1, $result);
+	}
+
 }