@Override
	protected String toDSL() {
		return String.format("file --outputType=text/plain --dir=%s",
				FixtureUtils.handleShellEscapeProcessing(file.getParent()));
	}
First make a temporary directory where our file will live.
spring-xd-test-fixtures/src/main/java/org/springframework/xd/test/fixtures/FileSource.java