public function data_mb_substr_phpcore_input_type_handling() {
    $heredoc = <<<EOT
hello world
EOT;

    return array(
      'integer zero'                   => array(
        'input'    => 0,
        'expected' => '0',
      ),
      'integer 1'                      => array(
        'input'    => 1,
        'expected' => '1',
      ),
      'positive integer'               => array(
        'input'    => 12345,
        'expected' => '12345',
      ),
      'negative integer'               => array(
        'input'    => -2345,
        'expected' => '-2345',
      ),
      // Float data.
      'positive float with fraction'   => array(
        'input'    => 10.5,
        'expected' => '10.5',
      ),
      'negative float with fraction'   => array(
        'input'    => -10.5,
        'expected' => '-10.5',
      ),
      'float scientific whole number'  => array(
        'input'    => 12.3456789000e10,
        'expected' => '12345',
      ),
      'float scientific with fraction' => array(
        'input'    => 12.3456789000E-10,
        'expected' => '1.234',
      ),
      'float, fraction only'           => array(
        'input'    => .5,
        'expected' => '0.5',
      ),
      // Null data.
      'null'                           => array(
        'input'    => null,
        'expected' => '',
      ),
      // Boolean data.
      'boolean true'                   => array(
        'input'    => true,
        'expected' => '1',
      ),
      'boolean false'                  => array(
        'input'    => false,
        'expected' => '',
      ),
      // Empty data.
      'empty string'                   => array(
        'input'    => '',
        'expected' => '',
      ),
      // String data.
      'double quoted string'           => array(
        'input'    => "string'",
        'expected' => 'strin',
      ),
      'single quoted string'           => array(
        'input'    => 'string',
        'expected' => 'strin',
      ),
      'heredoc string'                 => array(
        'input'    => $heredoc,
        'expected' => 'hello',
      ),
      // Object data.
      'object with __toString method'  => array(
        'input'    => new ClassWithToStringForMbSubstr(),
        'expected' => 'Class',
      ),
    );
  }