[bugfix] Slider: should not emit change event when value not changed (#4087)

src/slider/test/index.spec.js

@@ -116,3 +116,21 @@ it('bar height', () => {
 
   expect(wrapper).toMatchSnapshot();
 });
+
+it('should not emit change event when value not changed', () => {
+  const wrapper = mount(Slider, {
+    propsData: {
+      value: 50
+    },
+    listeners: {
+      input(value) {
+        wrapper.setProps({ value });
+      }
+    }
+  });
+
+  trigger(wrapper, 'click', 100, 0);
+  trigger(wrapper, 'click', 100, 0);
+
+  expect(wrapper.emitted('change').length).toEqual(1);
+});