fix(Dropdown): prefer key property for generated options

src/modules/Dropdown/Dropdown.js

@@ -1058,8 +1058,8 @@ export default class Dropdown extends Component {
     return (
       <select type='hidden' aria-hidden='true' name={name} value={value} multiple={multiple}>
         <option value='' />
-        {_.map(options, option => (
-          <option key={option.value} value={option.value}>{option.text}</option>
+        {_.map(options, (option, i) => (
+          <option key={option.key || `${option.value}-${i}`} value={option.value}>{option.text}</option>
         ))}
       </select>
     )
@@ -1152,7 +1152,7 @@ export default class Dropdown extends Component {
 
     return _.map(options, (opt, i) => (
       <DropdownItem
-        key={`${opt.value}-${i}`}
+        key={opt.key || `${opt.value}-${i}`}
         active={isActive(opt.value)}
         onClick={this.handleItemClick}
         selected={selectedIndex === i}

test/specs/modules/Dropdown/Dropdown-test.js

@@ -1835,6 +1835,28 @@ describe('Dropdown', () => {
     })
   })
 
+  describe('renderOptions', () => {
+    it('prefers the option\'s "key" property for keying generated DropdownItems', () => {
+      const customOptions = [
+        { text: '1', value: '1', key: 'a' },
+        { text: '2', value: '2', key: 'b' },
+      ]
+      wrapperShallow(<Dropdown options={customOptions} />)
+      wrapper.should.contain('DropdownItem[key="a"]')
+      wrapper.should.contain('DropdownItem[key="b"]')
+    })
+
+    it('generates a "key" property using the option.value if no key is provided', () => {
+      const customOptions = [
+        { text: '1', value: '1' },
+        { text: '2', value: '2' },
+      ]
+      wrapperShallow(<Dropdown options={customOptions} />)
+      wrapper.should.contain('DropdownItem[key="1-0"]')
+      wrapper.should.contain('DropdownItem[key="2-1"]')
+    })
+  })
+
   describe('Dropdown.Menu child', () => {
     it('renders child passed', () => {
       wrapperShallow(