@Test
	public void testJsonFilter() {
		String lastName = UUID.randomUUID().toString();
		String goodData = "{\"firstName\":\"good\", \"lastName\":\"g" + lastName + "\"}";
		String badData = "{\"firstName\":\"bad\", \"lastName\":\"b" + lastName + "\"}";

		stream(sources.http() + XD_DELIMITER
				+ " filter --expression=#jsonPath(payload,'$.firstName').contains('"
				+ "good') " + XD_DELIMITER
				+ sinks.file());

		sources.httpSource().postData(goodData);
		sources.httpSource().postData(badData);

		assertValid(goodData, sinks.file());
		assertReceived(1);
	}
Tests that a json string is written to file if it meets the filter criteria.
spring-xd-integration-test/src/test/java/org/springframework/xd/integration/test/ProcessorTest.java