FileUpload: associate the label with the input (#48766)

* FileUpload: associate the label with the input

* generate a unique id and set the correct role

* add a test to prevent regressions

packages/grafana-ui/src/components/FileUpload/FileUpload.test.tsx

@@ -1,4 +1,5 @@
 import { render, waitFor, fireEvent, screen } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
 import React from 'react';
 
 import { selectors } from '@grafana/e2e-selectors';
@@ -8,10 +9,23 @@ import { FileUpload } from './FileUpload';
 describe('FileUpload', () => {
   it('should render upload button with default text and no file name', () => {
     render(<FileUpload onFileUpload={() => {}} />);
-    expect(screen.getByText('Upload file')).toBeInTheDocument();
+    expect(screen.getByRole('button', { name: 'Upload file' })).toBeInTheDocument();
     expect(screen.queryByLabelText('File name')).toBeNull();
   });
 
+  it('clicking the button should trigger the input', async () => {
+    const mockInputOnClick = jest.fn();
+    const { getByTestId } = render(<FileUpload onFileUpload={() => {}} />);
+    const button = screen.getByRole('button', { name: 'Upload file' });
+    const input = getByTestId(selectors.components.FileUpload.inputField);
+
+    // attach a click listener to the input
+    input.onclick = mockInputOnClick;
+
+    await userEvent.click(button);
+    expect(mockInputOnClick).toHaveBeenCalled();
+  });
+
   it('should display uploaded file name', async () => {
     const testFileName = 'grafana.png';
     const file = new File(['(⌐□_□)'], testFileName, { type: 'image/png' });

packages/grafana-ui/src/components/FileUpload/FileUpload.tsx

@@ -1,5 +1,6 @@
 import { css, cx } from '@emotion/css';
 import React, { FC, FormEvent, useCallback, useState } from 'react';
+import { v4 as uuidv4 } from 'uuid';
 
 import { GrafanaTheme2 } from '@grafana/data';
 import { selectors } from '@grafana/e2e-selectors';
@@ -31,6 +32,7 @@ export const FileUpload: FC<Props> = ({
 }) => {
   const style = useStyles2(getStyles(size));
   const [fileName, setFileName] = useState('');
+  const id = uuidv4();
 
   const onChange = useCallback(
     (event: FormEvent<HTMLInputElement>) => {
@@ -47,14 +49,14 @@ export const FileUpload: FC<Props> = ({
     <>
       <input
         type="file"
-        id="fileUpload"
+        id={id}
         className={style.fileUpload}
         onChange={onChange}
         multiple={false}
         accept={accept}
         data-testid={selectors.components.FileUpload.inputField}
       />
-      <label className={cx(style.labelWrapper, className)}>
+      <label role="button" htmlFor={id} className={cx(style.labelWrapper, className)}>
         <Icon name="upload" className={style.icon} />
         {children}
       </label>