feat: Add a tag validation method

Author: xgourmandin

validator_instance.go

@@ -707,3 +707,22 @@ func (v *Validate) VarWithValueCtx(ctx context.Context, field interface{}, other
 	v.pool.Put(vd)
 	return
 }
+
+// ValidateTag validates a tag. It's main purpose is to be used when validating values directly via the Var, VarCtx,
+// VarWithValue and VarWithValueCtx methods to know beforehand if the tag is known by the library instead of managing
+// a panic error.
+//
+// Parameters:
+// tag (string): The tag to be validated.
+//
+// Returns:
+// error: An error signaling the given tag is invalid.
+func (v *Validate) ValidateTag(tag string) (err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			err = fmt.Errorf("error parsing tag: %v", r)
+		}
+	}()
+	v.parseFieldTagsRecursive(tag, "", "", false)
+	return err
+}

validator_test.go

@@ -13692,3 +13692,11 @@ func TestOmitNilAndRequired(t *testing.T) {
 		AssertError(t, err2, "OmitNil.Inner.Str", "OmitNil.Inner.Str", "Str", "Str", "required")
 	})
 }
+
+func TestValidate_ValidateTag(t *testing.T) {
+	validate := New()
+	err := validate.ValidateTag("nonexsiting,nonexisting2")
+	NotEqual(t, err, nil)
+	err = validate.ValidateTag("required,email")
+	Equal(t, err, nil)
+}