Added debug message section.

src/Command/InfectionCommand.php

@@ -219,7 +219,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
         $processBuilder = new ProcessBuilder($adapter, $config->getProcessTimeout());
         $testFrameworkOptions = $this->getTestFrameworkExtraOptions($testFrameworkKey);
 
-        $initialTestsRunner = new InitialTestsRunner($processBuilder, $this->eventDispatcher);
+        $initialTestsRunner = new InitialTestsRunner($processBuilder, $this->eventDispatcher, $metricsCalculator);
         $initialTestSuitProcess = $initialTestsRunner->run(
             $testFrameworkOptions->getForInitialProcess(),
             $this->skipCoverage,

src/Logger/DebugFileLogger.php

@@ -68,6 +68,18 @@ protected function getLogLines(): array
             'Not Covered'
         );
 
+        if (!empty($this->metricsCalculator->getDebugInfo())) {
+            $logs[] = '';
+            $logs[] = 'Debug Messages:';
+            $logs[] = '===============';
+            $logs[] = '';
+
+            foreach ($this->metricsCalculator->getDebugInfo() as $line) {
+                $logs[] = '';
+                $logs[] = $line;
+            }
+        }
+
         return $logs;
     }
 

src/Mutant/MetricsCalculator.php

@@ -98,6 +98,11 @@ class MetricsCalculator
      */
     private $totalMutantsCount = 0;
 
+    /**
+     * @var string[]
+     */
+    private $debugMessage = [];
+
     /**
      * Build a metric calculator with a sub-set of mutators
      *
@@ -274,4 +279,17 @@ public function getErrorProcesses(): array
     {
         return $this->errorProcesses;
     }
+
+    public function addDebugInfo(string $msg): void
+    {
+        $this->debugMessage[] = $msg;
+    }
+
+    /**
+     * @return string[]
+     */
+    public function getDebugInfo(): array
+    {
+        return $this->debugMessage;
+    }
 }

src/Process/Runner/InitialTestsRunner.php

@@ -39,6 +39,7 @@
 use Infection\Events\InitialTestCaseCompleted;
 use Infection\Events\InitialTestSuiteFinished;
 use Infection\Events\InitialTestSuiteStarted;
+use Infection\Mutant\MetricsCalculator;
 use Infection\Process\Builder\ProcessBuilder;
 use Symfony\Component\Process\Process;
 
@@ -57,10 +58,16 @@ final class InitialTestsRunner
      */
     private $eventDispatcher;
 
-    public function __construct(ProcessBuilder $processBuilder, EventDispatcherInterface $eventDispatcher)
+    /**
+     * @var MetricsCalculator
+     */
+    private $metrics;
+
+    public function __construct(ProcessBuilder $processBuilder, EventDispatcherInterface $eventDispatcher, MetricsCalculator $metrics)
     {
         $this->processBuilder = $processBuilder;
         $this->eventDispatcher = $eventDispatcher;
+        $this->metrics = $metrics;
     }
 
     public function run(string $testFrameworkExtraOptions, bool $skipCoverage, array $phpExtraOptions = []): Process
@@ -73,6 +80,20 @@ public function run(string $testFrameworkExtraOptions, bool $skipCoverage, array
 
         $this->eventDispatcher->dispatch(new InitialTestSuiteStarted());
 
+        $cmd = $process->getCommandLine();
+
+        if (!empty($cmd)) {
+            $this->metrics->addDebugInfo(
+                sprintf(
+                    '[%s()] Command:%s%s%s',
+                    __METHOD__,
+                    PHP_EOL,
+                    $cmd,
+                    PHP_EOL
+                )
+            );
+        }
+
         $process->run(function ($type) use ($process): void {
             if ($process::ERR === $type) {
                 $process->stop();

tests/Console/E2ETest.php

@@ -172,7 +172,14 @@ private function runOnE2EFixture($path): string
             $this->markTestSkipped('Saved golden output');
         }
 
-        $this->assertFileEquals('expected-output.txt', 'infection.log', sprintf('%s/expected-output.txt is not same as infection.log (if that is OK, run GOLDEN=1 vendor/bin/phpunit)', getcwd()));
+        $this->assertStringStartsWith(
+            file_get_contents('expected-output.txt'),
+            file_get_contents('infection.log'),
+            sprintf(
+                '%s/expected-output.txt is not same as infection.log (if that is OK, run GOLDEN=1 vendor/bin/phpunit)',
+                getcwd()
+            )
+        );
 
         return $output;
     }

tests/Mutant/MetricsCalculatorTest.php

@@ -65,6 +65,8 @@ public function test_it_shows_zero_values_by_default(): void
         $this->assertSame(0.0, $calculator->getMutationScoreIndicator());
         $this->assertSame(0.0, $calculator->getCoverageRate());
         $this->assertSame(0.0, $calculator->getCoveredCodeMutationScoreIndicator());
+
+        $this->assertSame([], $calculator->getDebugInfo());
     }
 
     public function test_it_collects_all_values(): void

tests/Process/Runner/InitialTestsRunnerTest.php

@@ -39,6 +39,7 @@
 use Infection\Events\InitialTestCaseCompleted;
 use Infection\Events\InitialTestSuiteFinished;
 use Infection\Events\InitialTestSuiteStarted;
+use Infection\Mutant\MetricsCalculator;
 use Infection\Process\Builder\ProcessBuilder;
 use Infection\Process\Runner\InitialTestsRunner;
 use PHPUnit\Framework\MockObject\MockObject;
@@ -78,7 +79,10 @@ public function test_it_dispatches_events(): void
                 $this->isInstanceOf(InitialTestSuiteFinished::class)
             );
 
-        $testRunner = new InitialTestsRunner($processBuilder, $eventDispatcher);
+        $metrics = $this->getMockBuilder(MetricsCalculator::class)->getMock();
+        $metrics->method('getDebugInfo')->willReturn(['test']);
+
+        $testRunner = new InitialTestsRunner($processBuilder, $eventDispatcher, $metrics);
 
         $testRunner->run('', false);
     }