fix(radio): only emit change event with user input

src/lib/radio/radio.spec.ts

@@ -152,21 +152,22 @@ describe('MdRadio', () => {
       expect(spies[1]).toHaveBeenCalledTimes(1);
     });
 
-    it('should emit a change event from the radio group', () => {
+    it('should not emit a change event from the radio group when change group value '
+         + 'programmatically', () => {
       expect(groupInstance.value).toBeFalsy();
 
       let changeSpy = jasmine.createSpy('radio-group change listener');
       groupInstance.change.subscribe(changeSpy);
 
-      groupInstance.value = 'fire';
+      radioLabelElements[0].click();
       fixture.detectChanges();
 
-      expect(changeSpy).toHaveBeenCalled();
+      expect(changeSpy).toHaveBeenCalledTimes(1);
 
       groupInstance.value = 'water';
       fixture.detectChanges();
 
-      expect(changeSpy).toHaveBeenCalledTimes(2);
+      expect(changeSpy).toHaveBeenCalledTimes(1);
     });
 
     // TODO(jelbourn): test this in an e2e test with *real* focus, rather than faking
@@ -242,34 +243,36 @@ describe('MdRadio', () => {
 
       fixture.detectChanges();
 
-      expect(changeSpy).toHaveBeenCalled();
+      expect(changeSpy).toHaveBeenCalledTimes(0);
       expect(groupInstance.value).toBeTruthy();
 
       radioInstances[0].checked = false;
 
       fixture.detectChanges();
 
-      expect(changeSpy).toHaveBeenCalledTimes(2);
+      expect(changeSpy).toHaveBeenCalledTimes(0);
       expect(groupInstance.value).toBeFalsy();
       expect(radioInstances.every(radio => !radio.checked)).toBe(true);
       expect(groupInstance.selected).toBeNull();
     });
 
-    it('should fire a change event from the group whenever a radio checked state changes', () => {
+    it('should not fire a change event from the group when a radio checked state changes', () => {
       let changeSpy = jasmine.createSpy('radio-group change listener');
       groupInstance.change.subscribe(changeSpy);
       radioInstances[0].checked = true;
 
       fixture.detectChanges();
 
-      expect(changeSpy).toHaveBeenCalled();
+      expect(changeSpy).toHaveBeenCalledTimes(0);
       expect(groupInstance.value).toBeTruthy();
+      expect(groupInstance.value).toBe('fire');
 
       radioInstances[1].checked = true;
 
       fixture.detectChanges();
 
-      expect(changeSpy).toHaveBeenCalledTimes(2);
+      expect(groupInstance.value).toBe('water');
+      expect(changeSpy).toHaveBeenCalledTimes(0);
     });
   });
 

src/lib/radio/radio.ts

@@ -127,11 +127,6 @@ export class MdRadioGroup implements AfterContentInit, ControlValueAccessor {
       this._value = newValue;
 
       this._updateSelectedRadioFromValue();
-
-      // Only fire a change event if this isn't the first time the value is ever set.
-      if (this._isInitialized) {
-        this._emitChangeEvent();
-      }
     }
   }
 
@@ -171,6 +166,13 @@ export class MdRadioGroup implements AfterContentInit, ControlValueAccessor {
     }
   }
 
+  emitChangeEvent(): void {
+    // Only fire a change event if this isn't the first time the value is ever set.
+    if (this._isInitialized) {
+      this._emitChangeEvent();
+    }
+  }
+
   private _updateRadioButtonNames(): void {
     if (this._radios) {
       this._radios.forEach(radio => {
@@ -418,12 +420,16 @@ export class MdRadioButton implements OnInit {
     // emit its event object to the `change` output.
     event.stopPropagation();
 
+    let groupValueChanged = this.value != this.radioGroup.value;
     this.checked = true;
     this._emitChangeEvent();
 
     if (this.radioGroup) {
       this.radioGroup._controlValueAccessorChangeFn(this.value);
       this.radioGroup._touch();
+      if (groupValueChanged) {
+        this.radioGroup.emitChangeEvent();
+      }
     }
   }