Refactor deviation calculations and enhance related tests

Author: andrey-helldar

src/Data/DeviationData.php

@@ -7,6 +7,6 @@
 readonly class DeviationData
 {
     public function __construct(
-        public MetricData $avg,
+        public MetricData $percent,
     ) {}
 }

src/Services/DeviationService.php

@@ -9,6 +9,8 @@
 use DragonCode\Benchmark\Data\ResultData;
 
 use function array_map;
+use function array_sum;
+use function count;
 use function sqrt;
 
 class DeviationService
@@ -55,58 +57,46 @@ protected function metric(array $item, string $key): MetricData
 
     protected function deviationMetric(array $item): DeviationData
     {
+        $time   = $this->result->values($item['avg'], 0, false);
+        $memory = $this->result->values($item['avg'], 1, false);
+
         return new DeviationData(
-            avg: $this->result->avg(
-                $this->result->values($item['deviation'], 0, false),
-                $this->result->values($item['deviation'], 1, false),
+            percent: $this->metricData(
+                $this->deviation($time),
+                $this->deviation($memory),
             ),
         );
     }
 
+    protected function metricData(float $time, float $memory): MetricData
+    {
+        return new MetricData($time, $memory);
+    }
+
     protected function flatten(array $collection): array
     {
-        $default = [];
-        $result  = [];
+        $result = [];
 
-        foreach ($collection as $i => $items) {
+        foreach ($collection as $items) {
             foreach ($items as $key => $item) {
                 $result[$key]['min'][]   = [$item->min->time, $item->min->memory];
                 $result[$key]['max'][]   = [$item->max->time, $item->max->memory];
                 $result[$key]['avg'][]   = [$item->avg->time, $item->avg->memory];
                 $result[$key]['total'][] = [$item->total->time, $item->total->memory];
-
-                if ($i === 0) {
-                    $default[$key] = [$item->avg->time, $item->avg->memory];
-
-                    continue;
-                }
-
-                $result[$key]['deviation'][] = [
-                    $this->percentage($default[$key][0], $this->deviation($default[$key][0], $item->avg->time)),
-                    $this->percentage($default[$key][1], $this->deviation($default[$key][1], $item->avg->memory)),
-                ];
             }
         }
 
         return $result;
     }
 
-    protected function deviation(float $first, float $second): float
+    protected function deviation(array $values): float
     {
-        $avg = ($first + $second) / 2;
-
-        $deviation1 = ($first - $avg) ** 2;
-        $deviation2 = ($second - $avg) ** 2;
+        $avg = array_sum($values) / count($values);
 
-        return sqrt(($deviation1 + $deviation2) / 2);
-    }
-
-    protected function percentage(float $reference, float $value): float
-    {
-        if ($reference === 0.0) {
-            return 0;
+        foreach ($values as &$value) {
+            $value = ($value - $avg) ** 2;
         }
 
-        return ($value - $reference) / $reference * 100;
+        return sqrt(array_sum($values) / count($values));
     }
 }

src/Transformers/ResultTransformer.php

@@ -54,7 +54,7 @@ protected function map(array $table, array $collection): array
             $table[3][$key] = $this->value($item->total);
             $table[5][$key] = 0;
 
-            if (! $deviation = $item->deviation?->avg) {
+            if (! $deviation = $item->deviation?->percent) {
                 continue;
             }
 
@@ -100,9 +100,11 @@ protected function value(MetricData $metric): string
             : sprintf('%s ms', $time);
     }
 
-    protected function deviation(float $value): ?string
+    protected function deviation(float $value): string
     {
-        return ($value > 0 ? '+' : '') . round($value, 2) . '%';
+        $value = round($value, 6);
+
+        return ($value > 0 ? '+' : '') . $value;
     }
 
     protected function time(float $value): float

…ts/Unit/Result/ToConsoleTest/output.snap …s/Unit/Result/ToConsoleTest/compare.snaptests/.pest/snapshots/Unit/Result/ToConsoleTest/output.snap renamed to tests/.pest/snapshots/Unit/Result/ToConsoleTest/compare.snap tests/.pest/snapshots/Unit/Result/ToConsoleTest/output.snap renamed to tests/.pest/snapshots/Unit/Result/ToConsoleTest/compare.snap

@@ -0,0 +1,17 @@
+
+ 0/1 [░░░░░░░░░░░░░░░░░░░░░░░░░░░░] 0% 1/1 [▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓] 100%
+
+
++------------------+-------------------------------+------------------------------+
+| #                | 0                             | 1                            |
++------------------+-------------------------------+------------------------------+
+| min              | 15.67890123 ms - 202 bytes    | 2.3456789 ms - 102 bytes     |
+| max              | 112.78901234 ms - 209 bytes   | 9.75678901 ms - 109 bytes    |
+| avg              | 53.02524845125 ms - 205 bytes | 5.94290024625 ms - 105 bytes |
+| total            | 848.40397522 ms - 3.21 KB     | 95.08640394 ms - 1.65 KB     |
++------------------+-------------------------------+------------------------------+
+| order            | 2                             | 1                            |
++------------------+-------------------------------+------------------------------+
+| deviation time   | 0                             | 0                            |
+| deviation memory | 0                             | 0                            |
++------------------+-------------------------------+------------------------------+

tests/.pest/snapshots/Unit/Result/ToConsoleTest/deviations.snap

@@ -2,8 +2,16 @@
 
 declare(strict_types=1);
 
-test('output', function () {
+test('compare', function () {
     benchmark()->toConsole();
 
     expectOutputToMatchSnapshot();
 });
+
+test('deviations', function () {
+    benchmark()
+        ->deviations()
+        ->toConsole();
+
+    expectOutputToMatchSnapshot();
+});