fix: alphaNumeric all chars banned (#550)

Author: xDivisionByZerox

src/random.ts

@@ -479,11 +479,17 @@ export class Random {
       'y',
       'z',
     ];
-    if (options) {
-      if (options.bannedChars) {
-        charsArray = arrayRemove(charsArray, options.bannedChars);
-      }
+
+    if (options.bannedChars) {
+      charsArray = arrayRemove(charsArray, options.bannedChars);
     }
+
+    if (charsArray.length === 0) {
+      throw new Error(
+        'Unable to generate string, because all possible characters are banned.'
+      );
+    }
+
     for (let i = 0; i < count; i++) {
       wholeString += this.faker.random.arrayElement(charsArray);
     }

test/random.spec.ts

@@ -210,7 +210,7 @@ describe('random', () => {
       expect(alphaText).match(/[b-oq-z]/);
     });
 
-    it.todo('should throw if all possible characters being banned', () => {
+    it('should throw if all possible characters being banned', () => {
       const bannedChars = 'abcdefghijklmnopqrstuvwxyz0123456789'.split('');
       expect(() =>
         faker.random.alphaNumeric(5, {