assertSame( $expected, $formatter->normalizeKey( $key ) ); } public function provideKeyNormalizations() { return [ [ 'a b', 'a_b' ], [ 'a __ b', 'a_b' ], [ ':', ':' ], [ "\t\n", ' ' ], [ "'", ''' ], [ "''", '''' ], [ '"%&/<>?[]{|}', '"%&/<>?[]{|}' ], [ 'ISBN', 'ISBN' ], ]; } }