Merge pull request nestjs#3594 from tonyhallett/to-be-string-does-not-execute

test(common): fix expect that does not execute

Author: kamilmysliwiec

packages/common/test/utils/random-string-generator.util.spec.ts

@@ -3,6 +3,6 @@ import { randomStringGenerator } from '../../utils/random-string-generator.util'
 
 describe('randomStringGenerator', () => {
   it('should generate random string', () => {
-    expect(randomStringGenerator()).to.be.string;
+    expect(randomStringGenerator()).to.be.a('string');
   });
 });