feat: add regex rule to StringValidator

Author: emyann

src/validation/reporter.spec.ts

@@ -201,6 +201,33 @@ describe('Reporter', () => {
           expect(errors[0]).toBe(message);
         }
       });
+
+      it('should report an error when string does not match specified regex', () => {
+        interface S {
+          s1: string;
+        }
+        interface T {
+          t1: string;
+        }
+
+        const REGEX = /^[0-9]+$/;
+        const VALUE = 'aaa';
+        const schema = createSchema<T, S>({
+          t1: {
+            fn: value => value.s1,
+            validation: Validation.string().regex(REGEX)
+          }
+        });
+        const result = morphism(schema, { s1: VALUE });
+        const error = new ValidationError({ targetProperty: 't1', expect: `value to match pattern: ${REGEX}`, value: VALUE });
+        const message = defaultFormatter(error);
+        const errors = reporter.report(result);
+        expect(errors).not.toBeNull();
+        if (errors) {
+          expect(errors.length).toEqual(1);
+          expect(errors[0]).toBe(message);
+        }
+      });
     });
 
     describe('number', () => {

src/validation/validators/StringValidator.ts

@@ -56,4 +56,17 @@ export class StringValidator extends BaseValidator<string> {
     });
     return this;
   }
+  regex(regex: RegExp) {
+    this.addRule({
+      name: 'regex',
+      expect: `value to match pattern: ${regex}`,
+      test: function(value) {
+        if (!regex.test(value)) {
+          throw new ValidatorError({ value, expect: this.expect });
+        }
+        return value;
+      }
+    });
+    return this;
+  }
 }