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<?php |
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use RandomLibTest\Mocks\Random\Mixer; |
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use RandomLibTest\Mocks\Random\Source; |
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use RandomLib\Generator; |
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class Vectors_Random_GeneratorTest extends PHPUnit_Framework_TestCase { |
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public static function provideGenerateInt() { |
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return array( |
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// First, lets test each offset based range |
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array(0, 7), |
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array(0, 15), |
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array(0, 31), |
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array(0, 63), |
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array(0, 127), |
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array(0, 255), |
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array(0, 511), |
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array(0, 1023), |
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// Let's try a range not starting at 0 |
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array(8, 15), |
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// Let's try a range with a negative number |
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array(-18, -11), |
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// Let's try a non-power-of-2 range |
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array(10, 100), |
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// Finally, let's try two large numbers |
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array(100000, 100007), |
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array(100000000, 100002047), |
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// Now, let's force a few loops by setting a valid offset |
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array(0, 5, 2), |
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array(0, 9, 5), |
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array(0, 27, 4), |
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); |
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} |
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public static function provideGenerators() { |
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$factory = new \RandomLib\Factory; |
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$generator = $factory->getLowStrengthGenerator(); |
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$sources = $generator->getSources(); |
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$ret = array(); |
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$ret[] = array(new Generator($sources, new \RandomLib\Mixer\Hash), 10000, 'hash'); |
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return $ret; |
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} |
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/** |
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* This test asserts that the algorithm that generates the integers does not |
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* actually introduce any bias into the generated numbers. If this test |
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* passes, the generated integers from the generator will be as unbiased as |
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* the sources that provide the data. |
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* |
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* @dataProvider provideGenerateInt |
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*/ |
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public function testGenerateInt($min, $max, $offset = 0) { |
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$generator = $this->getGenerator($max - $min + $offset); |
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for ($i = $max; $i >= $min; $i--) { |
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$this->assertEquals($i, $generator->generateInt($min, $max)); |
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} |
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} |
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/** |
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* This generator generates two bytes at a time, and uses each 8 bit segment of |
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* the generated byte as a coordinate on a grid (so 01011010 would be the |
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* coordinate (0101, 1010) or (5, 10). These are used as inputs to a MonteCarlo |
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* algorithm for the integral of y=x over a 15x15 grid. The expected answer is |
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* 1/2 * 15 * 15 (or 1/2 * base * height, since the result is a triangle). |
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* Therefore, if we get an answer close to that, we know the generator is good. |
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* |
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* Now, since the area under the line should be equal to the area above the line. |
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* Therefore, the ratio of the two areas should be equal. This way, we can avoid |
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* computing total to figure out the areas. |
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* |
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* I have set the bounds on the test to be 80% and 120%. Meaning that I will |
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* consider the test valid and unbiased if the number of random elements that |
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* fall under (inside) of the line and the number that fall outside of the line |
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* are at most 20% apart. |
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* |
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* Since testing randomness is not reliable or repeatable, I will only fail the |
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* test in two different scenarios. The first is if after the iterations the |
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* outside or the inside is 0. The chances of that happening are so low that |
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* if it happens, it's relatively safe to assume that something bad happened. The |
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* second scenario happens when the ratio is outside of the 20% tolerance. If |
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* that happens, I will re-run the entire test. If that test is outside of the 20% |
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* tolerance, then the test will fail |
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* |
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* |
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* @dataProvider provideGenerators |
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*/ |
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public function testGenerate(\RandomLib\Generator $generator, $times) { |
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$ratio = $this->doTestGenerate($generator, $times); |
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if ($ratio < 0.8 || $ratio > 1.2) { |
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$ratio2 = $this->doTestGenerate($generator, $times); |
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if ($ratio2 > 1.2 || $ratio2 < 0.8) { |
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$this->fail( |
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sprintf( |
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'The test failed multiple runs with final ratios %f and %f', |
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$ratio, |
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$ratio2 |
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) |
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); |
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} |
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} |
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} |
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protected function doTestGenerate(\RandomLib\Generator $generator, $times) { |
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$inside = 0; |
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$outside = 0; |
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$on = 0; |
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for ($i = 0; $i < $times; $i++) { |
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$byte = $generator->generate(2); |
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$byte = unpack('n', $byte); |
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$byte = array_shift($byte); |
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$xCoord = ($byte >> 8); |
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$yCoord = ($byte & 0xFF); |
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if ($xCoord < $yCoord) { |
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$outside++; |
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} elseif ($xCoord == $yCoord) { |
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$on++; |
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} else { |
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$inside++; |
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} |
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} |
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$this->assertGreaterThan(0, $outside, 'Outside Is 0'); |
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$this->assertGreaterThan(0, $inside, 'Inside Is 0'); |
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$ratio = $inside / $outside; |
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return $ratio; |
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} |
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public function getGenerator($random) { |
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$source1 = new Source(array( |
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'generate' => function ($size) use (&$random) { |
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$ret = pack('N', $random); |
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$random--; |
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return substr($ret, -1 * $size); |
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} |
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)); |
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$sources = array($source1); |
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$mixer = new Mixer(array( |
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'mix'=> function(array $sources) { |
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if (empty($sources)) return ''; |
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return array_pop($sources); |
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} |
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)); |
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return new Generator($sources, $mixer); |
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} |
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} |
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ircmaxell /
RandomLib
