feat: new helper functions to replace regexes #807

Implemented new StringUtil helper functions: splitCommaSeparated, sanitizeUrlPart, isValidFileName.
Added helper functions to HeaderUtil: matchesAuthorizationScheme, hasScheme.
Added unit tests for the new helper functions.
Refactored codebase to use helper functions instead of regexes if applicable.

test/unit/util/StringUtil.test.ts

@@ -0,0 +1,34 @@
+import {
+  sanitizeUrlPart,
+  splitCommaSeparated,
+  isValidFileName,
+} from '../../../src/util/StringUtil';
+
+describe('HeaderUtil', (): void => {
+  describe('#sanitizeUrlPart', (): void => {
+    it('sanitizes part of a URL by replacing non-word characters with dashes (\'-\').', (): void => {
+      expect(sanitizeUrlPart('$path segment containing=non-word+chars'))
+        .toBe('-path-segment-containing-non-word-chars');
+    });
+  });
+
+  describe('#splitCommaSeparated', (): void => {
+    it('splits strings containing commas into parts based on the location of these commas.', (): void => {
+      expect(splitCommaSeparated('this,is,a,comma-separated,string'))
+        .toEqual([ 'this', 'is', 'a', 'comma-separated', 'string' ]);
+    });
+    it('handles strings without commas by returning an array containing solely the original string.', (): void => {
+      const strVal = 'this string has no commas';
+      expect(splitCommaSeparated(strVal)).toEqual([ strVal ]);
+    });
+  });
+
+  describe('#validateFileName', (): void => {
+    it('returns true if the provided file name is valid.', (): void => {
+      expect(isValidFileName('valid-file.test')).toBeTruthy();
+    });
+    it('returns false if the provided file name is invalid.', (): void => {
+      expect(isValidFileName('$%^*')).toBeFalsy();
+    });
+  });
+});