test: improved pipeline tests

Author: petrknap

tests/FilterTest.php

@@ -11,6 +11,7 @@
 use PHPUnit\Framework\ExpectationFailedException;
 use PHPUnit\Framework\TestCase;
 use stdClass;
+use Symfony\Component\Process\Process;
 
 final class FilterTest extends TestCase
 {
@@ -77,26 +78,20 @@ public static function dataWritesToStreamsAndReturnsExpectedValue(): array
 
     public function testBuildsAndExecutesPipeline(): ProfileInterface
     {
-        $inputSizeInMiB = 16;
-        $outputSizeInB = 0;  # pre-allocated variable
-
         $nullInput = fopen('php://memory', 'r');
-        $generateData = new Filter('dd', ['if=/dev/random', 'bs=1M', 'count=' . $inputSizeInMiB]);
-        $forwardData = new Filter('cat');
+        $generateData = new Filter('dd', ['if=/dev/zero', 'bs=1M', 'count=16']);
+        $compressData = new Filter('gzip');
         $countBytes = new Filter('wc', ['--bytes']);
         $pipeline = $generateData
-            ->pipe($forwardData)
-            ->pipe($forwardData)
-            ->pipe($forwardData)
-            ->pipe($forwardData)
-            ->pipe($forwardData)
+            ->pipe($compressData)
             ->pipe($countBytes);
 
+        $pipelineOutput = 0;  # pre-allocated variable, must be set as `+=`
         $profiling = Profiling::start();
-        $outputSizeInB += (int) $pipeline->filter($nullInput);  # pre-allocated variable, must be set as `+=`
+        $pipelineOutput += (int) $pipeline->filter($nullInput);
         $profile = $profiling->finish();
 
-        self::assertSame($inputSizeInMiB * 1024 * 1024, $outputSizeInB);
+        self::assertSame(16303, $pipelineOutput);
 
         return $profile;
     }
@@ -114,17 +109,16 @@ public function testPipelineDoesNotHaveMemoryLeak(ProfileInterface $profile): vo
     #[Depends('testBuildsAndExecutesPipeline')]
     public function testPipelinePerformanceIsOk(ProfileInterface $profile): void
     {
-        $referenceProfiling = Profiling::start();
-        (
-            new Filter('wc', ['--bytes'])  # must be same as `$countBytes`
-        )->filter(
-            random_bytes(length: 1024 * 1024)  # must have same length as `dd bs=`
+        $referenceProcess = Process::fromShellCommandline(
+            'dd if=/dev/zero bs=1M count=16 | gzip | wc --bytes',  # must be same as $pipeline
         );
+        $referenceProfiling = Profiling::start();
+        $referenceProcess->mustRun();
         $referenceProfile = $referenceProfiling->finish();
 
         try {
             self::assertLessThanOrEqual(
-                $referenceProfile->getDuration() * 7,
+                $referenceProfile->getDuration() * 1.05,  # allow 5 % overhead
                 $profile->getDuration(),
             );
         } catch (ExpectationFailedException $expectationFailed) {