From 4a57dcfd8dcd32ae08daaea90e1e81d93f40e4f1 Mon Sep 17 00:00:00 2001
From: Pawel Kozlowski <pkozlowski.opensource@gmail.com>
Date: Wed, 5 Oct 2016 01:14:23 +0200
Subject: [PATCH] fix(forms): properly validate empty strings with patterns
 (#11450)

---
 modules/@angular/forms/src/validators.ts       | 1 -
 modules/@angular/forms/test/validators_spec.ts | 9 +++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/modules/@angular/forms/src/validators.ts b/modules/@angular/forms/src/validators.ts
index e0cd411c7e..865cdc0d0d 100644
--- a/modules/@angular/forms/src/validators.ts
+++ b/modules/@angular/forms/src/validators.ts
@@ -96,7 +96,6 @@ export class Validators {
    */
   static pattern(pattern: string): ValidatorFn {
     return (control: AbstractControl): {[key: string]: any} => {
-      if (isPresent(Validators.required(control))) return null;
       let regex = new RegExp(`^${pattern}$`);
       let v: string = control.value;
       return regex.test(v) ? null :
diff --git a/modules/@angular/forms/test/validators_spec.ts b/modules/@angular/forms/test/validators_spec.ts
index 921965171d..280a3241fd 100644
--- a/modules/@angular/forms/test/validators_spec.ts
+++ b/modules/@angular/forms/test/validators_spec.ts
@@ -91,6 +91,9 @@ export function main() {
       it('should not error on null',
          () => { expect(Validators.pattern('[a-zA-Z ]*')(new FormControl(null))).toEqual(null); });
 
+      it('should not error on null value and "null" pattern',
+         () => { expect(Validators.pattern('null')(new FormControl(null))).toEqual(null); });
+
       it('should not error on valid strings', () => {
         expect(Validators.pattern('[a-zA-Z ]*')(new FormControl('aaAA'))).toEqual(null);
       });
@@ -100,6 +103,12 @@ export function main() {
           'pattern': {'requiredPattern': '^[a-zA-Z ]*$', 'actualValue': 'aaa0'}
         });
       });
+
+      it('should error on failure to match empty string', () => {
+        expect(Validators.pattern('[a-zA-Z]+')(new FormControl(''))).toEqual({
+          'pattern': {'requiredPattern': '^[a-zA-Z]+$', 'actualValue': ''}
+        });
+      });
     });
 
     describe('compose', () => {