#767: Detect enum becoming non-enum and vice-versa as BC break

Author: bdsl

src/DetectChanges/BCBreak/ClassBased/CasesChanged.php

@@ -16,20 +16,26 @@
 
 class CasesChanged implements ClassBased
 {
-    public function __invoke(ReflectionClass $fromClass, ReflectionClass $toEnum): Changes
+    public function __invoke(ReflectionClass $fromClass, ReflectionClass $toClass): Changes
     {
-        if (! $fromClass instanceof ReflectionEnum) {
+        $fromEnumName = $fromClass->getName();
+        $fromKind = $this->kindOf($fromClass);
+        $toKind = $this->kindOf($toClass);
+
+        if (! $fromClass instanceof ReflectionEnum && ! $toClass instanceof ReflectionEnum) {
             return Changes::empty();
         }
 
-        if (! $toEnum instanceof ReflectionEnum) {
-            return Changes::empty();
+        if (! $fromClass instanceof ReflectionEnum && $toClass instanceof ReflectionEnum) {
+            return Changes::fromList(Change::changed("$fromKind " . $fromEnumName . " became enum"));
         }
 
-        $fromEnumName = $fromClass->getName();
+        if ($fromClass instanceof ReflectionEnum && ! $toClass instanceof ReflectionEnum) {
+            return Changes::fromList(Change::changed("enum " . $fromEnumName . " became " . $toKind));
+        }
 
         $addedCases = array_filter(
-            $toEnum->getCases(),
+            $toClass->getCases(),
             static function (ReflectionEnumCase $case) use ($fromClass): bool {
                 if (self::isInternalDocComment($case->getDocComment())) {
                     return false;
@@ -42,17 +48,17 @@ static function (ReflectionEnumCase $case) use ($fromClass): bool {
 
         $removedCases = array_filter(
             $fromClass->getCases(),
-            static function (ReflectionEnumCase $case) use ($toEnum): bool {
+            static function (ReflectionEnumCase $case) use ($toClass): bool {
                 if (self::isInternalDocComment($case->getDocComment())) {
                     return false;
                 }
 
-                return ! $toEnum->hasCase($case->getName());
+                return ! $toClass->hasCase($case->getName());
             },
         );
 
         $internalisedCases = array_filter(
-            $toEnum->getCases(),
+            $toClass->getCases(),
             static function (ReflectionEnumCase $case) use ($fromClass) {
                 if (! self::isInternalDocComment($case->getDocComment())) {
                     return false;
@@ -105,4 +111,22 @@ private static function isInternalDocComment(string|null $comment): bool
         return $comment !== null
             && Regex\matches($comment, '/\s+@internal\s+/');
     }
+
+    /** @psalm-return 'enum'|'interface'|'trait'|'class' */
+    private function kindOf(ReflectionClass $reflectionClass): string
+    {
+        if ($reflectionClass->isEnum()) {
+            return 'enum';
+        }
+
+        if ($reflectionClass->isInterface()) {
+            return 'interface';
+        }
+
+        if ($reflectionClass->isTrait()) {
+            return 'trait';
+        }
+
+        return 'class';
+    }
 }

test/unit/DetectChanges/BCBreak/ClassBased/EnumCasesChangedTest.php

@@ -38,7 +38,7 @@ public function testDiffs(
         );
     }
 
-    public function testReturnsNoChangesIfOldEnumIsNotEnum(): void
+    public function testReturnsClassBecameEnumError(): void
     {
         // EnumCasesChanged should not be called when the old symbol is not an Enum. If it does it will
         // just return an empty list.
@@ -48,10 +48,15 @@ public function testReturnsNoChangesIfOldEnumIsNotEnum(): void
             ReflectionClass::createFromName(DummyEnum::class),
         );
 
-        $this->assertSame(0, $changes->count());
+        $this->assertEquals(
+            [
+                Change::changed("class stdClass became enum")
+            ],
+            \iterator_to_array($changes)
+        );
     }
 
-    public function testReturnsNoChangesIfNewEnumIsNotEnum(): void
+    public function testReturnsEnumBecameClassError(): void
     {
         // EnumCasesChanged should not be called when the old symbol is not an Enum. If it does it will
         // just return an empty list.
@@ -61,7 +66,12 @@ public function testReturnsNoChangesIfNewEnumIsNotEnum(): void
             ReflectionClass::createFromName(stdClass::class),
         );
 
-        $this->assertSame(0, $changes->count());
+        $this->assertEquals(
+            [
+                Change::changed("enum RoaveTest\BackwardCompatibility\DetectChanges\BCBreak\ClassBased\DummyEnum became class")
+            ],
+            \iterator_to_array($changes)
+        );
     }
 
     /**