class PercentagesTest

class PercentagesTest extends UnitTestCase {
    
    /**
     * @dataProvider providerTestPercentages
     * @covers ::format
     */
    public function testPercentages($total, $current, $expected_result) : void {
        $actual_result = Percentage::format($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,
                'expected_result' => '20',
            ],
            [
                'total' => 1,
                'current' => 200 / 501,
                'expected_result' => '40',
            ],
            [
                'total' => 1,
                'current' => 300 / 501,
                'expected_result' => '60',
            ],
            [
                'total' => 1,
                'current' => 400 / 501,
                'expected_result' => '80',
            ],
            [
                'total' => 1,
                'current' => 500 / 501,
                'expected_result' => '99.8',
            ],
        ];
    }

}