[new feature] Stepper: add show-plus & show-minus prop (#4056)

src/stepper/test/__snapshots__/index.spec.js.snap

@@ -5,3 +5,5 @@ exports[`disable stepper input 1`] = `<div class="van-stepper"><button class="va
 exports[`disabled stepper 1`] = `<div class="van-stepper"><button class="van-stepper__minus van-stepper__minus--disabled"></button><input type="number" role="spinbutton" aria-valuemax="Infinity" aria-valuemin="1" aria-valuenow="1" disabled="disabled" class="van-stepper__input"><button class="van-stepper__plus van-stepper__plus--disabled"></button></div>`;
 
 exports[`input width 1`] = `<div class="van-stepper"><button class="van-stepper__minus van-stepper__minus--disabled"></button><input type="number" role="spinbutton" aria-valuemax="Infinity" aria-valuemin="1" aria-valuenow="1" class="van-stepper__input" style="width: 10rem;"><button class="van-stepper__plus"></button></div>`;
+
+exports[`show-plus & show-minus props 1`] = `<div class="van-stepper"><button class="van-stepper__minus van-stepper__minus--disabled" style="display: none;"></button><input type="number" role="spinbutton" aria-valuemax="Infinity" aria-valuemin="1" aria-valuenow="1" class="van-stepper__input"><button class="van-stepper__plus" style="display: none;"></button></div>`;

src/stepper/test/index.spec.js

@@ -176,3 +176,14 @@ test('min value is 0', () => {
 
   expect(wrapper.emitted('input')[0][0]).toEqual(0);
 });
+
+test('show-plus & show-minus props', () => {
+  const wrapper = mount(Stepper, {
+    propsData: {
+      showPlus: false,
+      showMinus: false
+    }
+  });
+
+  expect(wrapper).toMatchSnapshot();
+});