fix(number-input): toFormValue should handle both undefined and null (#870)

Author: emmenko

src/components/inputs/number-input/number-input.js

@@ -60,8 +60,15 @@ NumberInput.defaultProps = {
   horizontalConstraint: 'scale',
 };
 
-NumberInput.toFormValue = numberOrString =>
-  typeof numberOrString === 'undefined' ? '' : numberOrString;
+NumberInput.toFormValue = numberOrString => {
+  if (
+    typeof numberOrString === 'number' ||
+    typeof numberOrString === 'string'
+  ) {
+    return numberOrString;
+  }
+  return '';
+};
 
 NumberInput.isEmpty = value => {
   if (typeof value === 'string') return value.trim().length === 0;

src/components/inputs/number-input/number-input.spec.js

@@ -16,10 +16,11 @@ describe('NumberInput.toFormValue', () => {
       expect(NumberInput.toFormValue('3,4')).toEqual('3,4');
     });
   });
-  describe('when called with undefined', () => {
+  describe('when called with undefined or null', () => {
     it('should return an empty string', () => {
       expect(NumberInput.toFormValue()).toEqual('');
       expect(NumberInput.toFormValue(undefined)).toEqual('');
+      expect(NumberInput.toFormValue(null)).toEqual('');
     });
   });
 });