[EuiSelect] allow select's value to be reset with an undefined value

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## [`master`](https://github.com/elastic/eui/tree/master)
 
 - Added a `size` prop to `EuiContextMenu` and added a smaller size ([#4409](https://github.com/elastic/eui/pull/4409))
+- Removed selected item of `EuiSelect` when `hasNoInitialSelection=true` and value reset to `undefined` ([#4428](https://github.com/elastic/eui/pull/4428))
 
 ## [`31.2.0`](https://github.com/elastic/eui/tree/v31.2.0)
 

src/components/form/select/select.test.tsx

@@ -16,9 +16,10 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+/* eslint-disable no-irregular-whitespace */
 
 import React from 'react';
-import { render } from 'enzyme';
+import { render, mount } from 'enzyme';
 import { requiredProps } from '../../../test/required_props';
 
 import { EuiSelect } from './select';
@@ -31,7 +32,7 @@ jest.mock('../validatable_control', () => ({
 }));
 
 describe('EuiSelect', () => {
-  test('is rendered', () => {
+  it('is rendered', () => {
     const component = render(
       <EuiSelect id="id" name="name" {...requiredProps} />
     );
@@ -40,7 +41,7 @@ describe('EuiSelect', () => {
   });
 
   describe('props', () => {
-    test('options are rendered', () => {
+    it('options are rendered', () => {
       const component = render(
         <EuiSelect
           options={[
@@ -53,25 +54,25 @@ describe('EuiSelect', () => {
       expect(component).toMatchSnapshot();
     });
 
-    test('isInvalid is rendered', () => {
+    it('isInvalid is rendered', () => {
       const component = render(<EuiSelect isInvalid />);
 
       expect(component).toMatchSnapshot();
     });
 
-    test('fullWidth is rendered', () => {
+    it('fullWidth is rendered', () => {
       const component = render(<EuiSelect fullWidth />);
 
       expect(component).toMatchSnapshot();
     });
 
-    test('isLoading is rendered', () => {
+    it('isLoading is rendered', () => {
       const component = render(<EuiSelect isLoading />);
 
       expect(component).toMatchSnapshot();
     });
 
-    test('disabled options are rendered', () => {
+    it('disabled options are rendered', () => {
       const component = render(
         <EuiSelect
           options={[
@@ -84,7 +85,7 @@ describe('EuiSelect', () => {
       expect(component).toMatchSnapshot();
     });
 
-    test('value option is rendered', () => {
+    it('value option is rendered', () => {
       const component = render(
         <EuiSelect
           options={[
@@ -99,4 +100,68 @@ describe('EuiSelect', () => {
       expect(component).toMatchSnapshot();
     });
   });
+
+  describe('hasNoInitialSelection', () => {
+    it('renders with an extra option at the top', () => {
+      const component = mount(
+        <EuiSelect
+          hasNoInitialSelection
+          options={[
+            { value: '1', text: 'Option #1' },
+            { value: '2', text: 'Option #2' },
+          ]}
+          onChange={() => {}}
+        />
+      );
+
+      expect(component.find('option').length).toBe(3);
+      expect(component.find('option').at(0)).toMatchInlineSnapshot(`
+        <option
+          disabled={true}
+          hidden={true}
+          style={
+            Object {
+              "display": "none",
+            }
+          }
+          value=""
+        >
+
+        </option>
+`);
+    });
+
+    it('can be reset to an empty initial selection', () => {
+      const component = mount(
+        <EuiSelect
+          hasNoInitialSelection
+          value="1"
+          options={[
+            { value: '1', text: 'Option #1' },
+            { value: '2', text: 'Option #2' },
+          ]}
+          onChange={() => {}}
+        />
+      );
+
+      expect(
+        component.find('select').getDOMNode<HTMLSelectElement>().value
+      ).toBe('1');
+
+      component.setProps({ value: '' });
+      expect(
+        component.find('select').getDOMNode<HTMLSelectElement>().value
+      ).toBe('');
+
+      component.setProps({ value: '1' });
+      expect(
+        component.find('select').getDOMNode<HTMLSelectElement>().value
+      ).toBe('1');
+
+      component.setProps({ value: undefined });
+      expect(
+        component.find('select').getDOMNode<HTMLSelectElement>().value
+      ).toBe('');
+    });
+  });
 });

src/components/form/select/select.tsx

@@ -83,12 +83,16 @@ export const EuiSelect: FunctionComponent<EuiSelectProps> = ({
   hasNoInitialSelection = false,
   defaultValue,
   compressed = false,
-  value,
+  value: _value,
   prepend,
   append,
   onMouseUp,
   ...rest
 }) => {
+  // if this is injecting an empty option for `hasNoInitialSelection` then
+  // value needs to fallback to an empty string to interact properly with `defaultValue`
+  const value = hasNoInitialSelection ? _value ?? '' : _value;
+
   const handleMouseUp = (e: React.MouseEvent<HTMLSelectElement>) => {
     // Normalizes cross-browser mouse eventing by preventing propagation,
     // notably for use in conjunction with EuiOutsideClickDetector.