fix(VSelect): show falsy items in the list

see #4431, #4649, 43a18b6

Author: KaelWD

src/components/VSelect/VSelectList.js

@@ -204,7 +204,7 @@ export default {
       return Boolean(getPropertyFromItem(item, this.itemDisabled, false))
     },
     getText (item) {
-      return (getPropertyFromItem(item, this.itemText, item) || '').toString()
+      return String(getPropertyFromItem(item, this.itemText, item))
     },
     getValue (item) {
       return getPropertyFromItem(item, this.itemValue, this.getText(item))
@@ -218,7 +218,8 @@ export default {
         this.hasItem(item)
       ) continue
 
-      if (item.header) children.push(this.genHeader(item))
+      if (item == null) children.push(this.genTile(item))
+      else if (item.header) children.push(this.genHeader(item))
       else if (item.divider) children.push(this.genDivider(item))
       else children.push(this.genTile(item))
     }

test/unit/components/VSelect/VSelectList.spec.js

@@ -118,4 +118,15 @@ test('VSelect', ({ mount, compileToFunctions }) => {
 
     expect(wrapper.find('.v-list__tile').length).toBe(1)
   })
+
+  // https://github.com/vuetifyjs/vuetify/issues/4431
+  it('should display falsy items', () => {
+    const wrapper = mount(VSelectList, {
+      propsData: {
+        items: [0, null, false, undefined, '']
+      }
+    })
+
+    expect(wrapper.html()).toMatchSnapshot()
+  })
 })

test/unit/components/VSelect/__snapshots__/VSelectList.spec.js.snap

@@ -1,5 +1,58 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`VSelect should display falsy items 1`] = `
+
+<div class="v-select-list v-card">
+  <div class="v-list">
+    <div>
+      <a class="v-list__tile v-list__tile--link">
+        <div class="v-list__tile__content">
+          <div class="v-list__tile__title">
+            0
+          </div>
+        </div>
+      </a>
+    </div>
+    <div>
+      <a class="v-list__tile v-list__tile--link">
+        <div class="v-list__tile__content">
+          <div class="v-list__tile__title">
+            null
+          </div>
+        </div>
+      </a>
+    </div>
+    <div>
+      <a class="v-list__tile v-list__tile--link">
+        <div class="v-list__tile__content">
+          <div class="v-list__tile__title">
+            false
+          </div>
+        </div>
+      </a>
+    </div>
+    <div>
+      <a class="v-list__tile v-list__tile--link">
+        <div class="v-list__tile__content">
+          <div class="v-list__tile__title">
+            undefined
+          </div>
+        </div>
+      </a>
+    </div>
+    <div>
+      <a class="v-list__tile v-list__tile--link">
+        <div class="v-list__tile__content">
+          <div class="v-list__tile__title">
+          </div>
+        </div>
+      </a>
+    </div>
+  </div>
+</div>
+
+`;
+
 exports[`VSelect should display no-data-text when item slot is provided 1`] = `
 
 <div class="v-select-list v-card">