@Override
  public FastAppend appendFile(DataFile file) {
    Preconditions.checkNotNull(file, "Invalid data file: null");
    if (newFilePaths.add(file.path())) {
      this.hasNewFiles = true;
      newFiles.add(file);
      summaryBuilder.addedFile(spec, file);
    }

    return this;
  }
@TestTemplate
  public void appendNullFile() {
    assertThatThrownBy(() -> table.newFastAppend().appendFile(null).commit())
        .isInstanceOf(NullPointerException.class)
        .hasMessage("Invalid data file: null");
  }