fix(striker-ui): add testLength() and make test defaults optional

striker-ui/lib/test_input/testInput.ts

@@ -55,7 +55,7 @@ const testInput: TestInputFunction = ({
         min: dMin = 0,
         onSuccess: dOnSuccess,
         value: dValue = null,
-      },
+      } = {},
       onFinishBatch,
       optionalTests,
       tests: requiredTests,

striker-ui/lib/test_input/testLength.ts

@@ -0,0 +1,23 @@
+import { MinimalInputTestArgs } from '../../types/TestInputFunction';
+
+const testLength: (
+  args: Pick<MinimalInputTestArgs, 'value'> &
+    Partial<Pick<MinimalInputTestArgs, 'max' | 'min'>>,
+) => boolean = ({ max, min, value }) => {
+  const { length } = String(value);
+
+  let isGEMin = true;
+  let isLEMax = true;
+
+  if (min) {
+    isGEMin = length >= min;
+  }
+
+  if (max) {
+    isLEMax = length <= max;
+  }
+
+  return isGEMin && isLEMax;
+};
+
+export default testLength;

striker-ui/types/TestInputFunction.ts

@@ -18,8 +18,8 @@ export type InputTest = {
 
 export type InputTestBatches = {
   [id: string]: {
-    defaults: InputTestArgs & {
+    defaults?: InputTestArgs & {
-      onSuccess: () => void;
+      onSuccess?: () => void;
     };
     onFinishBatch?: () => void;
     optionalTests?: Array<InputTest>;