Checkbox - add validation if no choice is selected

packages/checkbox/README.md

@@ -41,6 +41,7 @@ const answer = await checkbox({
 | choices  | `Array<{ value: string, name?: string, disabled?: boolean \| string, checked?: boolean } \| Separator>` | yes      | List of the available choices. The `value` will be returned as the answer, and used as display if no `name` is defined. Choices who're `disabled` will be displayed, but not selectable. |
 | pageSize | `number`                                                                                                | no       | By default, lists of choice longer than 7 will be paginated. Use this option to control how many choices will appear on the screen at once.                                              |
 | loop     | `boolean`                                                                                               | no       | Defaults to `true`. When set to `false`, the cursor will be constrained to the top and bottom of the choice list without looping.                                                        |
+| required | `boolean`                                                                                               | no       | When set to `true`, ensures at least one choice must be selected.                                                                                                                        |
 
 The `Separator` object can be used to render non-selectable lines in the choice list. By default it'll render a line, but you can provide the text as argument (`new Separator('-- Dependencies --')`). This option is often used to add labels to groups within long list of options.
 

packages/checkbox/checkbox.test.mts

@@ -624,4 +624,43 @@ describe('checkbox prompt', () => {
       '"[checkbox prompt] No selectable choices. All choices are disabled."',
     );
   });
+
+  it('shows validation message if user did not select any choice', async () => {
+    const { answer, events, getScreen } = await render(checkbox, {
+      message: 'Select a number',
+      choices: numberedChoices,
+      required: true,
+    });
+
+    events.keypress('enter');
+    expect(getScreen()).toMatchInlineSnapshot(`
+      "? Select a number (Press <space> to select, <a> to toggle all, <i> to invert
+      selection, and <enter> to proceed)
+      ❯◯ 1
+       ◯ 2
+       ◯ 3
+       ◯ 4
+       ◯ 5
+       ◯ 6
+       ◯ 7
+      (Use arrow keys to reveal more choices)
+      > At least one choice must be selected"
+    `);
+
+    events.keypress('space');
+    expect(getScreen()).toMatchInlineSnapshot(`
+      "? Select a number
+      ❯◉ 1
+       ◯ 2
+       ◯ 3
+       ◯ 4
+       ◯ 5
+       ◯ 6
+       ◯ 7
+      (Use arrow keys to reveal more choices)"
+    `);
+
+    events.keypress('enter');
+    await expect(answer).resolves.toEqual([1]);
+  });
 });

packages/checkbox/src/index.mts

@@ -32,6 +32,7 @@
   instructions?: string | boolean;
   choices: ReadonlyArray<Choice<Value> | Separator>;
   loop?: boolean;
+  required?: boolean;
 }>;
 
 type Item<Value> = Separator | Choice<Value>;
@@ -74,7 +75,14 @@
 
 export default createPrompt(
   <Value extends unknown>(config: Config<Value>, done: (value: Array<Value>) => void) => {
-    const { prefix = usePrefix(), instructions, pageSize, loop = true, choices } = config;
+    const {
+      prefix = usePrefix(),
+      instructions,
+      pageSize,
+      loop = true,
+      choices,
+      required,
+    } = config;
     const [status, setStatus] = useState('pending');
     const [items, setItems] = useState<ReadonlyArray<Item<Value>>>(
       choices.map((choice) => ({ ...choice })),
@@ -82,7 +90,7 @@
 
     const bounds = useMemo(() => {
       const first = items.findIndex(isSelectable);
       // TODO: Replace with `findLastIndex` when it's available.
       const last = items.length - 1 - [...items].reverse().findIndex(isSelectable);
 
       if (first < 0) {
@@ -96,11 +104,16 @@
 
     const [active, setActive] = useState(bounds.first);
     const [showHelpTip, setShowHelpTip] = useState(true);
+    const [errorMsg, setError] = useState<string | undefined>(undefined);
 
     useKeypress((key) => {
       if (isEnterKey(key)) {
-        setStatus('done');
-        done(items.filter(isChecked).map((choice) => choice.value));
+        if (required && !items.some(isChecked)) {
+          setError('At least one choice must be selected');
+        } else {
+          setStatus('done');
+          done(items.filter(isChecked).map((choice) => choice.value));
+        }
       } else if (isUpKey(key) || isDownKey(key)) {
         if (!loop && active === bounds.first && isUpKey(key)) return;
         if (!loop && active === bounds.last && isDownKey(key)) return;
@@ -111,6 +124,7 @@
         } while (!isSelectable(items[next]!));
         setActive(next);
       } else if (isSpaceKey(key)) {
+        setError(undefined);
         setShowHelpTip(false);
         setItems(items.map((choice, i) => (i === active ? toggle(choice) : choice)));
       } else if (key.name === 'a') {
@@ -162,7 +176,12 @@
       }
     }
 
-    return `${prefix} ${message}${helpTip}\n${page}${ansiEscapes.cursorHide}`;
+    let error = '';
+    if (errorMsg) {
+      error = chalk.red(`> ${errorMsg}`);
+    }
+
+    return `${prefix} ${message}${helpTip}\n${page}\n${error}${ansiEscapes.cursorHide}`;
   },
 );