@Test
  public void testDownloadNotExists() throws Exception {
    when(mockBlockBlobAsyncClient.downloadWithResponse(any(), any(), any(), anyBoolean())).thenReturn(
        Mono.error(mock(BlobStorageException.class)));
    expectBlobStorageException(() -> downloadBlob(blobId));
  }
Test download of non existent blob
@throws Exception
ambry-cloud/src/test/java/com/github/ambry/cloud/azure/AzureBlobDataAccessorTest.java