Add empty string validation for Tags and Authors

x-pack/plugins/security_solution/public/detections/components/rules/step_about_rule/field_validators.ts

@@ -0,0 +1,25 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { ValidationFunc, ERROR_CODE } from '../../../../shared_imports';
+
+export const emptyArrayItem = (message: string) => (
+  ...args: Parameters<ValidationFunc>
+): ReturnType<ValidationFunc<FormData, ERROR_CODE>> => {
+  const [{ value }] = args;
+
+  if (typeof value !== 'string') {
+    return;
+  }
+
+  return value.trim() === ''
+    ? {
+        code: 'ERR_INVALID_CHARS',
+        message,
+      }
+    : undefined;
+};

x-pack/plugins/security_solution/public/detections/components/rules/step_about_rule/schema.tsx

@@ -38,6 +38,19 @@ export const schema: FormSchema<AboutStepRule> = {
       }
     ),
     labelAppend: OptionalFieldLabel,
+    validations: [
+      {
+        validator: emptyArrayItem(
+          i18n.translate(
+            'xpack.securitySolution.detectionEngine.createRule.stepAboutRule.tagFieldEmptyError',
+            {
+              defaultMessage: 'An author must not be empty',
+            }
+          )
+        ),
+        type: 'arrayItem',
+      },
+    ],
   },
   name: {
     type: FIELD_TYPES.TEXT,
@@ -243,6 +256,19 @@ export const schema: FormSchema<AboutStepRule> = {
       }
     ),
     labelAppend: OptionalFieldLabel,
+    validations: [
+      {
+        validator: emptyArrayItem(
+          i18n.translate(
+            'xpack.securitySolution.detectionEngine.createRule.stepAboutRule.tagFieldEmptyError',
+            {
+              defaultMessage: 'A tag must not be empty',
+            }
+          )
+        ),
+        type: 'arrayItem',
+      },
+    ],
   },
   note: {
     type: FIELD_TYPES.TEXTAREA,