prevent Data to be unkown

Author: pikax

src/mount.ts

@@ -34,8 +34,8 @@ import { stubComponents } from './stubs'
 
 type Slot = VNode | string | { render: Function }
 
-interface MountingOptions<Props, Data = {}> {
-  data?: () => Data
+interface MountingOptions<Props, Data extends object = {}> {
+  data?: () => Data extends unknown ? never : Data
   props?: Props
   attrs?: Record<string, unknown>
   slots?: {

test-dts/mount.d-test.ts

@@ -20,6 +20,17 @@ expectType<string>(
   }).vm.a
 )
 
+// no data provided
+expectError(
+  mount(AppWithDefine, {
+    data() {
+      return {
+        myVal: 1
+      }
+    }
+  })
+)
+
 // can receive extra props
 // ideally, it should not
 // but the props have type { a: string } & VNodeProps