feat: add hasOption tester

Adds the new "hasOption" util to check for the existence of an option.

packages/core/src/testers/testers.ts

@@ -31,6 +31,7 @@ import isArray from 'lodash/isArray';
 import reduce from 'lodash/reduce';
 import toPairs from 'lodash/toPairs';
 import includes from 'lodash/includes';
+import isUndefined from 'lodash/isUndefined';
 import type {
   Categorization,
   ControlElement,
@@ -215,6 +216,23 @@ export const optionIs =
     return !isEmpty(options) && options[optionName] === optionValue;
   };
 
+/**
+ * Checks whether the given UI schema has an option with the given
+ * name. If no options property is set, returns false.
+ *
+ * @param {string} optionName the name of the option to check
+ */
+export const hasOption =
+  (optionName: string): Tester =>
+  (uischema: UISchemaElement): boolean => {
+    if (isEmpty(uischema)) {
+      return false;
+    }
+
+    const options = uischema.options;
+    return !isEmpty(options) && !isUndefined(options[optionName]);
+  };
+
 /**
  * Only applicable for Controls.
  *

packages/core/test/testers.test.ts

@@ -54,6 +54,7 @@ import {
   JsonSchema,
   LabelElement,
   UISchemaElement,
+  hasOption,
 } from '../src';
 
 const test = anyTest as TestInterface<{ uischema: ControlElement }>;
@@ -183,6 +184,30 @@ test('optionIs should return false for UI schema elements without options cell',
   t.false(optionIs('answer', 42)(control, undefined, undefined));
 });
 
+test('hasOption should check for options', (t) => {
+  const control: ControlElement = {
+    type: 'Control',
+    scope: '#/properties/bar',
+    options: {
+      answer: 42,
+    },
+  };
+  t.true(hasOption('answer')(control, undefined, undefined));
+});
+
+test('hasOption should not fail if uischema is undefined or null', (t) => {
+  const uischema: UISchemaElement = null;
+  t.false(hasOption('answer')(uischema, undefined, undefined));
+});
+
+test('hasOption should return false for UI schema elements without options cell', (t) => {
+  const control: ControlElement = {
+    type: 'Control',
+    scope: '#/properties/bar',
+  };
+  t.false(hasOption('answer')(control, undefined, undefined));
+});
+
 test('schemaMatches should check type sub-schema of control via predicate', (t) => {
   const schema: JsonSchema = {
     type: 'object',