Add JOIN support to JDatabaseQuery UPDATE query

libraries/joomla/database/databasequery.php

@@ -349,6 +349,16 @@ public function __toString()
 
 			case 'update':
 				$query .= (string) $this->update;
+
+				if ($this->join)
+				{
+					// special case for joins
+					foreach ($this->join as $join)
+					{
+						$query .= (string) $join;
+					}
+				}
+
 				$query .= (string) $this->set;
 
 				if ($this->where)

tests/suite/joomla/database/JDatabaseQueryTest.php

@@ -157,6 +157,34 @@ public function test__toStringSelect()
 		);
 	}
 
+	/**
+	 * Test for the JDatabaseQuery::__string method for a 'update' case.
+	 *
+	 * @return  void
+	 *
+	 * @since   11.3
+	 */
+	public function test__toStringUpdate()
+	{
+		$q = new JDatabaseQueryInspector($this->dbo);
+
+		$q->update('#__foo AS a')
+			->join('INNER', 'b ON b.id = a.id')
+			->set('a.id = 2')
+			->where('b.id = 1');
+
+		$this->assertThat(
+			(string) $q,
+			$this->equalTo(
+				"\nUPDATE #__foo AS a" .
+				"\nINNER JOIN b ON b.id = a.id" .
+				"\nSET a.id = 2" .
+				"\nWHERE b.id = 1"
+			),
+			'Tests for correct rendering.'
+		);
+	}
+
 	/**
 	 * Test for the castAsChar method.
 	 *