fix: implement validity property for form controls

Author: madsrasmussen

packages/uui-base/lib/mixins/FormControlMixin.ts

@@ -16,6 +16,7 @@ export declare abstract class FormControlMixinInterface extends LitElement {
   formResetCallback(): void;
   checkValidity(): boolean;
   get validationMessage(): string;
+  get validity(): ValidityState;
   public setCustomValidity(error: string): void;
   protected _value: FormDataEntryValue | FormData;
   protected _internals: any;
@@ -302,6 +303,9 @@ export const FormControlMixin = <T extends Constructor<LitElement>>(
 
       const hasError = Object.values(this._validityState).includes(true);
 
+      // https://developer.mozilla.org/en-US/docs/Web/API/ValidityState#valid
+      this._validityState.valid = !hasError;
+
       if (hasError) {
         this.dispatchEvent(
           new UUIFormControlEvent(UUIFormControlEvent.INVALID)
@@ -347,6 +351,11 @@ export const FormControlMixin = <T extends Constructor<LitElement>>(
       return this._internals?.checkValidity();
     }
 
+    // https://developer.mozilla.org/en-US/docs/Web/API/HTMLObjectElement/validity
+    public get validity(): ValidityState {
+      return this._validityState;
+    }
+
     get validationMessage() {
       return this._internals?.validationMessage;
     }