fix(class): #5624 Reset direction to default in classDiagram

packages/mermaid/src/diagrams/class/classDb.ts

@@ -113,6 +113,7 @@ export const clear = function () {
   functions.push(setupToolTips);
   namespaces = new Map();
   namespaceCounter = 0;
+  direction = 'TB';
   commonClear();
 };
 

packages/mermaid/src/diagrams/class/classDiagram.spec.ts

@@ -444,6 +444,17 @@ class C13["With Città foreign language"]
         ]
       `);
     });
+
+    it('should revert direction to default once direction is removed', () => {
+      parser.parse(`classDiagram
+          direction RL
+          class A`);
+      expect(classDb.getDirection()).toBe('RL');
+      classDb.clear();
+      parser.parse(`classDiagram
+          class B`);
+      expect(classDb.getDirection()).toBe('TB');
+    });
   });
 
   describe('when parsing class defined in brackets', function () {