[Caching] Cache dry-run files whose FileDiff has no content change

src/Application/ApplicationFileProcessor.php

@@ -192,7 +192,9 @@ private function processFile(File $file, Configuration $configuration): FileProc
 
         if ($fileProcessResult->getSystemErrors() !== []) {
             $this->changedFilesDetector->invalidateFile($file->getFilePath());
-        } elseif (! $configuration->isDryRun() || ! $fileProcessResult->getFileDiff() instanceof FileDiff) {
+        } elseif (! $configuration->isDryRun() || ! $fileProcessResult->hasChanged()) {
+            // gate on the actual content change, not on FileDiff: a FileDiff also carries reported line changes
+            // that print identically, and such files would otherwise be re-processed on every dry run
             // selective runs are safe to cache now — the key is scoped to the rule selection
             $this->changedFilesDetector->cacheFile($file->getFilePath());
         }

tests/Application/ApplicationFileProcessor/ApplicationFileProcessorTest.php

@@ -43,6 +43,42 @@ public function testCleanFileIsCachedAsUnchanged(): void
         $this->assertFalse($this->changedFilesDetector->hasFileChanged($filePath));
     }
 
+    public function testDryRunCachesFileWhoseReportedChangesLeaveContentUnchanged(): void
+    {
+        self::$rectorConfig = null;
+        $this->bootFromConfigFiles([__DIR__ . '/config-import-names.php']);
+        $applicationFileProcessor = $this->make(ApplicationFileProcessor::class);
+        $changedFilesDetector = $this->make(ChangedFilesDetector::class);
+
+        $filePath = __DIR__ . '/Source/WithAliasedImportOfSameShortName.php';
+
+        // name importing reports line changes here, but the printed file is identical, so the diff is empty
+        $processResult = $applicationFileProcessor->processFiles([$filePath], new Configuration(isDryRun: true));
+
+        $fileDiffs = $processResult->getFileDiffs(onlyWithChanges: false);
+        $this->assertCount(1, $fileDiffs);
+        $this->assertSame('', $fileDiffs[0]->getDiff());
+        $this->assertFalse($changedFilesDetector->hasFileChanged($filePath));
+
+        $changedFilesDetector->clear();
+    }
+
+    public function testDryRunDoesNotCacheFileWithPendingChanges(): void
+    {
+        self::$rectorConfig = null;
+        $this->bootFromConfigFiles([__DIR__ . '/config-max-changes.php']);
+        $applicationFileProcessor = $this->make(ApplicationFileProcessor::class);
+        $changedFilesDetector = $this->make(ChangedFilesDetector::class);
+
+        $filePath = __DIR__ . '/Source/WithTwoClosuresFirst.php';
+
+        $applicationFileProcessor->processFiles([$filePath], new Configuration(isDryRun: true));
+
+        $this->assertTrue($changedFilesDetector->hasFileChanged($filePath));
+
+        $changedFilesDetector->clear();
+    }
+
     public function testOnlyRuleRunCachesUnderOwnScopeWithoutPoisoningFullRun(): void
     {
         $filePath = __DIR__ . '/Source/CleanFile.php';

tests/Application/ApplicationFileProcessor/Source/Rules/Money.php

@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\Tests\Application\ApplicationFileProcessor\Source\Rules;
+
+final class Money
+{
+}

tests/Application/ApplicationFileProcessor/Source/ValueObjects/Money.php

@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\Tests\Application\ApplicationFileProcessor\Source\ValueObjects;
+
+final class Money
+{
+}

tests/Application/ApplicationFileProcessor/Source/WithAliasedImportOfSameShortName.php

@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\Tests\Application\ApplicationFileProcessor\Source;
+
+use Rector\Tests\Application\ApplicationFileProcessor\Source\Rules\Money;
+use Rector\Tests\Application\ApplicationFileProcessor\Source\ValueObjects\Money as MoneyValue;
+
+final class WithAliasedImportOfSameShortName
+{
+    public function rule(): Money
+    {
+        return new Money();
+    }
+
+    public function value(): MoneyValue
+    {
+        return new MoneyValue();
+    }
+}

tests/Application/ApplicationFileProcessor/config-import-names.php

@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+use Rector\Config\RectorConfig;
+use Rector\Php80\Rector\Class_\StringableForToStringRector;
+
+return static function (RectorConfig $rectorConfig): void {
+    $rectorConfig->cacheDirectory(sys_get_temp_dir() . '/_rector_import_names_test');
+    $rectorConfig->importNames();
+    $rectorConfig->rule(StringableForToStringRector::class);
+};