class PercentagesTest

class PercentagesTest extends UnitTestCase {
  protected $testCases = [];

  /**
   * @dataProvider providerTestPercentages
   * @covers ::format
   */
  public function testPercentages($total, $current, $expected_result) {
    $actual_result = Percentage::format($total, $current);
    $this
      ->assertEquals($actual_result, $expected_result, sprintf('The expected the batch api percentage at the state %s/%s is %s%% and got %s%%.', $current, $total, $expected_result, $actual_result));
  }

  /**
   * Provide data for batch unit tests.
   *
   * @return array
   *   An array of data used by the test.
   */
  public static function providerTestPercentages() {

    // Set up an array of test cases.
    return [
      // array(total, current, expected).
      // 1/2 is 50%.
      [
        2,
        1,
        '50',
      ],
      // Though we should never encounter a case where the current set is set
      // 0, if we did, we should get 0%.
      [
        3,
        0,
        '0',
      ],
      // 1/3 is closer to 33% than to 34%.
      [
        3,
        1,
        '33',
      ],
      // 2/3 is closer to 67% than to 66%.
      [
        3,
        2,
        '67',
      ],
      // 1/199 should round up to 1%.
      [
        199,
        1,
        '1',
      ],
      // 198/199 should round down to 99%.
      [
        199,
        198,
        '99',
      ],
      // 199/200 would have rounded up to 100%, which would give the false
      // impression of being finished, so we add another digit and should get
      // 99.5%.
      [
        200,
        199,
        '99.5',
      ],
      // The same logic holds for 1/200: we should get 0.5%.
      [
        200,
        1,
        '0.5',
      ],
      // Numbers that come out evenly, such as 50/200, should be forced to have
      // extra digits for consistency.
      [
        200,
        50,
        '25.0',
      ],
      // Regardless of number of digits we're using, 100% should always just be
      // 100%.
      [
        200,
        200,
        '100',
      ],
      // 1998/1999 should similarly round down to 99.9%.
      [
        1999,
        1998,
        '99.9',
      ],
      // 1999/2000 should add another digit and go to 99.95%.
      [
        2000,
        1999,
        '99.95',
      ],
      // 19999/20000 should add yet another digit and go to 99.995%.
      [
        20000,
        19999,
        '99.995',
      ],
      // The next five test cases simulate a batch with a single operation
      // ('total' equals 1) that takes several steps to complete. Within the
      // operation, we imagine that there are 501 items to process, and 100 are
      // completed during each step. The percentages we get back should be
      // rounded the usual way for the first few passes (i.e., 20%, 40%, etc.),
      // but for the last pass through, when 500 out of 501 items have been
      // processed, we do not want to round up to 100%, since that would
      // erroneously indicate that the processing is complete.
      [
        'total' => 1,
        'current' => 100 / 501,
        '20',
      ],
      [
        'total' => 1,
        'current' => 200 / 501,
        '40',
      ],
      [
        'total' => 1,
        'current' => 300 / 501,
        '60',
      ],
      [
        'total' => 1,
        'current' => 400 / 501,
        '80',
      ],
      [
        'total' => 1,
        'current' => 500 / 501,
        '99.8',
      ],
    ];
  }

}