remove one more usage of fs.promises

src/core/server/uuid/resolve_uuid.test.ts

@@ -17,15 +17,15 @@
  * under the License.
  */
 
-import { promises } from 'fs';
+import Fs from 'fs';
 import { join } from 'path';
 import { resolveInstanceUuid } from './resolve_uuid';
 import { configServiceMock } from '../config/config_service.mock';
 import { loggingServiceMock } from '../logging/logging_service.mock';
 import { BehaviorSubject } from 'rxjs';
 import { Logger } from '../logging';
 
-const { readFile, writeFile } = promises;
+const { readFile, writeFile } = Fs;
 
 jest.mock('uuid', () => ({
   v4: () => 'NEW_UUID',
@@ -35,11 +35,8 @@ jest.mock('fs', () => {
   const actual = jest.requireActual('fs');
   return {
     ...actual,
-    promises: {
-      ...actual.promises,
-      readFile: jest.fn(() => Promise.resolve('')),
-      writeFile: jest.fn(() => Promise.resolve('')),
-    },
+    readFile: jest.fn().mockImplementation((...args) => process.nextTick(args.pop())),
+    writeFile: jest.fn().mockImplementation((...args) => process.nextTick(args.pop())),
   };
 });
 

src/core/server/uuid/resolve_uuid.ts

@@ -18,15 +18,17 @@
  */
 
 import uuid from 'uuid';
-import { promises } from 'fs';
+import Fs from 'fs';
+import { promisify } from 'util';
 import { join } from 'path';
 import { take } from 'rxjs/operators';
 import { IConfigService } from '../config';
 import { PathConfigType, config as pathConfigDef } from '../path';
 import { HttpConfigType, config as httpConfigDef } from '../http';
 import { Logger } from '../logging';
 
-const { readFile, writeFile } = promises;
+const readFile = promisify(Fs.readFile);
+const writeFile = promisify(Fs.writeFile);
 
 const FILE_ENCODING = 'utf8';
 const FILE_NAME = 'uuid';