public File newFile(String fileName) {
    return createFile(directory, fileName);
  }
Creates a new file with the given name in the specified {@link #directory}.

@param fileName the name of the file to create.

@return the file that was created.

@throws IllegalStateException if the file already exists.
@throws IllegalStateException if there is an {@link IOException} while creating the file.
geode-junit/src/main/java/org/apache/geode/test/junit/rules/TemporaryFileRule.java