public ParserBuilder inputPath(Path inputPath) {
            if (inputPath == null) {
                throw new NullPointerException("inputPath");
            }
            this.inputPath = inputPath;
            return this;
        }
This method returns PreviewResult.

@return PreviewResult returns the result by PreviewExecutor
@throws IOException in case of failures in file operations
embulk-junit4/src/main/java/org/embulk/test/TestingEmbulk.java