Implement cache format versioning

Author: sebastianbergmann

src/StaticAnalysis/CachingCoveredFileAnalyser.php

@@ -16,6 +16,8 @@
  */
 final class CachingCoveredFileAnalyser extends Cache implements CoveredFileAnalyser
 {
+    private const CACHE_FORMAT_VERSION = 2;
+
     /**
      * @var CoveredFileAnalyser
      */
@@ -80,8 +82,10 @@ public function ignoredLinesFor(string $filename): array
 
     public function process(string $filename): void
     {
-        if ($this->has($filename, __CLASS__)) {
-            $this->cache[$filename] = $this->read($filename, __CLASS__, [LinesOfCode::class]);
+        $cacheKey = __CLASS__ . self::CACHE_FORMAT_VERSION;
+
+        if ($this->has($filename, $cacheKey)) {
+            $this->cache[$filename] = $this->read($filename, $cacheKey, [LinesOfCode::class]);
 
             return;
         }
@@ -94,6 +98,6 @@ public function process(string $filename): void
             'ignoredLinesFor' => $this->coveredFileAnalyser->ignoredLinesFor($filename),
         ];
 
-        $this->write($filename, __CLASS__, $this->cache[$filename]);
+        $this->write($filename, $cacheKey, $this->cache[$filename]);
     }
 }