class DrupalJSONTest

class DrupalJSONTest extends DrupalUnitTestCase {
  public static function getInfo() {
    return array(
      'name' => 'JSON',
      'description' => 'Perform unit tests on the drupal_json_encode() and drupal_json_decode() functions.',
      'group' => 'System',
    );
  }

  /**
   * Tests converting PHP variables to JSON strings and back.
   */
  function testJSON() {

    // Setup a string with the full ASCII table.
    // @todo: Add tests for non-ASCII characters and Unicode.
    $str = '';
    for ($i = 0; $i < 128; $i++) {
      $str .= chr($i);
    }

    // Characters that must be escaped.
    // We check for unescaped " separately.
    $html_unsafe = array(
      '<',
      '>',
      '\'',
      '&',
    );

    // The following are the encoded forms of: < > ' & "
    $html_unsafe_escaped = array(
      '\\u003C',
      '\\u003E',
      '\\u0027',
      '\\u0026',
      '\\u0022',
    );

    // Verify there aren't character encoding problems with the source string.
    $this
      ->assertIdentical(strlen($str), 128, 'A string with the full ASCII table has the correct length.');
    foreach ($html_unsafe as $char) {
      $this
        ->assertTrue(strpos($str, $char) > 0, format_string('A string with the full ASCII table includes @s.', array(
        '@s' => $char,
      )));
    }

    // Verify that JSON encoding produces a string with all of the characters.
    $json = drupal_json_encode($str);
    $this
      ->assertTrue(strlen($json) > strlen($str), 'A JSON encoded string is larger than the source string.');

    // The first and last characters should be ", and no others.
    $this
      ->assertTrue($json[0] == '"', 'A JSON encoded string begins with ".');
    $this
      ->assertTrue($json[strlen($json) - 1] == '"', 'A JSON encoded string ends with ".');
    $this
      ->assertTrue(substr_count($json, '"') == 2, 'A JSON encoded string contains exactly two ".');

    // Verify that encoding/decoding is reversible.
    $json_decoded = drupal_json_decode($json);
    $this
      ->assertIdentical($str, $json_decoded, 'Encoding a string to JSON and decoding back results in the original string.');

    // Verify reversibility for structured data. Also verify that necessary
    // characters are escaped.
    $source = array(
      TRUE,
      FALSE,
      0,
      1,
      '0',
      '1',
      $str,
      array(
        'key1' => $str,
        'key2' => array(
          'nested' => TRUE,
        ),
      ),
    );
    $json = drupal_json_encode($source);
    foreach ($html_unsafe as $char) {
      $this
        ->assertTrue(strpos($json, $char) === FALSE, format_string('A JSON encoded string does not contain @s.', array(
        '@s' => $char,
      )));
    }

    // Verify that JSON encoding escapes the HTML unsafe characters
    foreach ($html_unsafe_escaped as $char) {
      $this
        ->assertTrue(strpos($json, $char) > 0, format_string('A JSON encoded string contains @s.', array(
        '@s' => $char,
      )));
    }
    $json_decoded = drupal_json_decode($json);
    $this
      ->assertNotIdentical($source, $json, 'An array encoded in JSON is not identical to the source.');
    $this
      ->assertIdentical($source, $json_decoded, 'Encoding structured data to JSON and decoding back results in the original data.');
  }

}