Add test for duplicate spec names

Author: paulbalandan

tests/AutoReview/SpecificationConformanceTest.php

@@ -388,6 +388,7 @@ private static function loadSourceClasses(): void
             ),
         );
         $sourceClasses = [];
+        $classesWithDuplicateSpecNames = [];
 
         /** @var \SplFileInfo $file */
         foreach ($iterator as $file) {
@@ -410,7 +411,26 @@ private static function loadSourceClasses(): void
                 $basename = str_replace('JsonRpc', 'JSONRPC', $basename);
             }
 
-            $sourceClasses[$basename] = $sourceClass;
+            if (! \array_key_exists($basename, $sourceClasses)) {
+                $sourceClasses[$basename] = $sourceClass;
+            } else {
+                $classesWithDuplicateSpecNames[$basename] = $sourceClass;
+            }
+        }
+
+        if ([] !== $classesWithDuplicateSpecNames) {
+            self::fail(\sprintf(
+                "The following classes have duplicate spec names:\n%s",
+                implode("\n", array_map(
+                    static fn(string $class, string $sourceClass): string => \sprintf(
+                        '* %s (%s)',
+                        $class,
+                        addslashes($sourceClass),
+                    ),
+                    array_keys($classesWithDuplicateSpecNames),
+                    $classesWithDuplicateSpecNames,
+                )),
+            ));
         }
 
         ksort($sourceClasses);