fix(forms): the min and max validators should work correctly with…

… `0` as a value

Prior to this change the `min` and `max` validator directives would not
set the `min` and `max` attributes on the host element. The problem was
caused by the truthy check in host binding expression that was
calculated as `false` when `0` is used as a value. This commit updates
the logic to leverage nullish coalescing operator in these host binding
expressions, so `0` is treated as a valid value, thus the `min` and
`max` attributes are set correctly.

Partially closes #42267

packages/forms/src/directives/validators.ts

@@ -167,7 +167,7 @@ export const MAX_VALIDATOR: StaticProvider = {
   selector:
       'input[type=number][max][formControlName],input[type=number][max][formControl],input[type=number][max][ngModel]',
   providers: [MAX_VALIDATOR],
-  host: {'[attr.max]': 'max ? max : null'}
+  host: {'[attr.max]': 'max ?? null'}
 })
 export class MaxValidator extends AbstractValidatorDirective implements OnChanges {
   /**
@@ -227,7 +227,7 @@ export const MIN_VALIDATOR: StaticProvider = {
   selector:
       'input[type=number][min][formControlName],input[type=number][min][formControl],input[type=number][min][ngModel]',
   providers: [MIN_VALIDATOR],
-  host: {'[attr.min]': 'min ? min : null'}
+  host: {'[attr.min]': 'min ?? null'}
 })
 export class MinValidator extends AbstractValidatorDirective implements OnChanges {
   /**

packages/forms/test/reactive_integration_spec.ts

@@ -2558,8 +2558,23 @@ const ValueAccessorB = createControlValueAccessor('[cva-b]');
             fixture.componentInstance.max = 1;
             fixture.detectChanges();
 
+            expect(input.getAttribute('max')).toEqual('1');
             expect(form.valid).toBeFalse();
             expect(form.controls.pin.errors).toEqual({max: {max: 1, actual: 2}});
+
+            fixture.componentInstance.min = 0;
+            fixture.componentInstance.max = 0;
+            fixture.detectChanges();
+            expect(input.getAttribute('min')).toEqual('0');
+            expect(input.getAttribute('max')).toEqual('0');
+            expect(form.valid).toBeFalse();
+            expect(form.controls.pin.errors).toEqual({max: {max: 0, actual: 2}});
+
+            input.value = 0;
+            dispatchEvent(input, 'input');
+            fixture.detectChanges();
+            expect(form.valid).toBeTruthy();
+            expect(form.controls.pin.errors).toBeNull();
           });
 
           it('should validate max for float number', () => {
@@ -2573,6 +2588,7 @@ const ValueAccessorB = createControlValueAccessor('[cva-b]');
             const input = fixture.debugElement.query(By.css('input')).nativeElement;
             const form = fixture.componentInstance.form;
 
+            expect(input.getAttribute('max')).toEqual('10.35');
             expect(input.value).toEqual('10.25');
             expect(form.valid).toBeTruthy();
             expect(form.controls.pin.errors).toBeNull();
@@ -2586,6 +2602,7 @@ const ValueAccessorB = createControlValueAccessor('[cva-b]');
             fixture.componentInstance.max = 10.05;
             fixture.detectChanges();
 
+            expect(input.getAttribute('max')).toEqual('10.05');
             expect(form.valid).toBeFalse();
             expect(form.controls.pin.errors).toEqual({max: {max: 10.05, actual: 10.15}});
 
@@ -2618,6 +2635,7 @@ const ValueAccessorB = createControlValueAccessor('[cva-b]');
 
             fixture.componentInstance.max = 1;
             fixture.detectChanges();
+            expect(input.getAttribute('max')).toEqual('1');
             expect(form.valid).toBeFalse();
             expect(form.controls.pin.errors).toEqual({max: {max: 1, actual: 2}});
           });
@@ -2644,8 +2662,23 @@ const ValueAccessorB = createControlValueAccessor('[cva-b]');
 
             fixture.componentInstance.min = 5;
             fixture.detectChanges();
+            expect(input.getAttribute('min')).toEqual('5');
             expect(form.valid).toBeFalse();
             expect(form.controls.pin.errors).toEqual({min: {min: 5, actual: 2}});
+
+            fixture.componentInstance.min = 0;
+            input.value = -5;
+            dispatchEvent(input, 'input');
+            fixture.detectChanges();
+            expect(input.getAttribute('min')).toEqual('0');
+            expect(form.valid).toBeFalse();
+            expect(form.controls.pin.errors).toEqual({min: {min: 0, actual: -5}});
+
+            input.value = 0;
+            dispatchEvent(input, 'input');
+            fixture.detectChanges();
+            expect(form.valid).toBeTruthy();
+            expect(form.controls.pin.errors).toBeNull();
           });
 
           it('should validate min for float number', () => {
@@ -2660,6 +2693,8 @@ const ValueAccessorB = createControlValueAccessor('[cva-b]');
             const input = fixture.debugElement.query(By.css('input')).nativeElement;
             const form = fixture.componentInstance.form;
 
+            expect(input.getAttribute('min')).toEqual('10.25');
+            expect(input.getAttribute('max')).toEqual('10.5');
             expect(input.value).toEqual('10.25');
             expect(form.valid).toBeTruthy();
             expect(form.controls.pin.errors).toBeNull();
@@ -2672,6 +2707,7 @@ const ValueAccessorB = createControlValueAccessor('[cva-b]');
 
             fixture.componentInstance.min = 10.40;
             fixture.detectChanges();
+            expect(input.getAttribute('min')).toEqual('10.4');
             expect(form.valid).toBeFalse();
             expect(form.controls.pin.errors).toEqual({min: {min: 10.40, actual: 10.35}});
 
@@ -2704,6 +2740,7 @@ const ValueAccessorB = createControlValueAccessor('[cva-b]');
 
             fixture.componentInstance.min = 5;
             fixture.detectChanges();
+            expect(input.getAttribute('min')).toEqual('5');
             expect(form.valid).toBeFalse();
             expect(form.controls.pin.errors).toEqual({min: {min: 5, actual: 2}});
           });

packages/forms/test/template_integration_spec.ts

@@ -1524,6 +1524,7 @@ import {NgModelCustomComp, NgModelCustomWrapper} from './value_accessor_integrat
            input.value = '';
            dispatchEvent(input, 'input');
            fixture.detectChanges();
+           expect(input.getAttribute('max')).toEqual('10');
            expect(form.valid).toEqual(true);
            expect(form.controls.max.errors).toBeNull();
 
@@ -1538,6 +1539,21 @@ import {NgModelCustomComp, NgModelCustomWrapper} from './value_accessor_integrat
            fixture.detectChanges();
            expect(form.valid).toEqual(true);
            expect(form.controls.max.errors).toBeNull();
+
+           fixture.componentInstance.max = 0;
+           fixture.detectChanges();
+           tick();
+           dispatchEvent(input, 'input');
+           fixture.detectChanges();
+           expect(input.getAttribute('max')).toEqual('0');
+           expect(form.valid).toEqual(false);
+           expect(form.controls.max.errors).toEqual({max: {max: 0, actual: 9}});
+
+           input.value = 0;
+           dispatchEvent(input, 'input');
+           fixture.detectChanges();
+           expect(form.valid).toEqual(true);
+           expect(form.controls.max.errors).toBeNull();
          }));
 
       it('should validate max for float number', fakeAsync(() => {
@@ -1552,6 +1568,7 @@ import {NgModelCustomComp, NgModelCustomWrapper} from './value_accessor_integrat
            input.value = '';
            dispatchEvent(input, 'input');
            fixture.detectChanges();
+           expect(input.getAttribute('max')).toEqual('10.25');
            expect(form.valid).toEqual(true);
            expect(form.controls.max.errors).toBeNull();
 
@@ -1586,6 +1603,7 @@ import {NgModelCustomComp, NgModelCustomWrapper} from './value_accessor_integrat
            input.value = '11';
            dispatchEvent(input, 'input');
            fixture.detectChanges();
+           expect(input.getAttribute('max')).toEqual('10');
            expect(form.valid).toEqual(false);
            expect(form.controls.max.errors).toEqual({max: {max: 10, actual: 11}});
 
@@ -1635,6 +1653,7 @@ import {NgModelCustomComp, NgModelCustomWrapper} from './value_accessor_integrat
            input.value = '';
            dispatchEvent(input, 'input');
            fixture.detectChanges();
+           expect(input.getAttribute('min')).toEqual('10');
            expect(form.valid).toEqual(true);
            expect(form.controls.min.errors).toBeNull();
 
@@ -1649,6 +1668,22 @@ import {NgModelCustomComp, NgModelCustomWrapper} from './value_accessor_integrat
            fixture.detectChanges();
            expect(form.valid).toEqual(false);
            expect(form.controls.min.errors).toEqual({min: {min: 10, actual: 9}});
+
+           fixture.componentInstance.min = 0;
+           fixture.detectChanges();
+           tick();
+           input.value = -5;
+           dispatchEvent(input, 'input');
+           fixture.detectChanges();
+           expect(input.getAttribute('min')).toEqual('0');
+           expect(form.valid).toEqual(false);
+           expect(form.controls.min.errors).toEqual({min: {min: 0, actual: -5}});
+
+           input.value = 0;
+           dispatchEvent(input, 'input');
+           fixture.detectChanges();
+           expect(form.valid).toEqual(true);
+           expect(form.controls.min.errors).toBeNull();
          }));
 
       it('should validate min for float number', fakeAsync(() => {
@@ -1663,6 +1698,7 @@ import {NgModelCustomComp, NgModelCustomWrapper} from './value_accessor_integrat
            input.value = '';
            dispatchEvent(input, 'input');
            fixture.detectChanges();
+           expect(input.getAttribute('min')).toEqual('10.25');
            expect(form.valid).toEqual(true);
            expect(form.controls.min.errors).toBeNull();
 
@@ -1696,6 +1732,7 @@ import {NgModelCustomComp, NgModelCustomWrapper} from './value_accessor_integrat
            input.value = '11';
            dispatchEvent(input, 'input');
            fixture.detectChanges();
+           expect(input.getAttribute('min')).toEqual('10');
            expect(form.valid).toEqual(true);
            expect(form.controls.min.errors).toBeNull();