Testing

For unit tests, use only the Go standard library testing package. To make comparing complex structures less verbose, we use the assert package from the testify library.

For parser and decoder tests, it’s a good practice to have an array with test cases containing the inputs and expected outputs. For an example, see the Test_splitCookiesHeader unit test in beats/packetbeat/protos/http/http_test.go in the Beats GitHub repository.

You can also have unit tests that treat the whole module as a black box, calling its interface functions, then reading the result and checking it. This pattern is especially useful for checking corner cases related to packet boundaries or correlation issues. Here is an example from the HTTP module:

func Test_gap_in_body_http1dot0_fin(t *testing.T) {
	if testing.Verbose() { 
		logp.LogInit(logp.LOG_DEBUG, "", false, true, []string{"http",
			"httpdetailed"})
	}
	http := HttpModForTests()

	data1 := []byte("GET / HTTP/1.0\r\n\r\n") 

	data2 := []byte("HTTP/1.0 200 OK\r\n" +
		"Date: Tue, 14 Aug 2012 22:31:45 GMT\r\n" +
		"Expires: -1\r\n" +
		"Cache-Control: private, max-age=0\r\n" +
		"Content-Type: text/html; charset=UTF-8\r\n" +
		"Content-Encoding: gzip\r\n" +
		"Server: gws\r\n" +
		"X-XSS-Protection: 1; mode=block\r\n" +
		"X-Frame-Options: SAMEORIGIN\r\n" +
		"\r\n" +
		"xxxxxxxxxxxxxxxxxxxx")

	tcptuple := testCreateTCPTuple()
	req := protos.Packet{Payload: data1}
	resp := protos.Packet{Payload: data2}

	private := protos.ProtocolData(new(httpConnectionData))

	private = http.Parse(&req, tcptuple, 0, private) 
	private = http.ReceivedFin(tcptuple, 0, private)

	private = http.Parse(&resp, tcptuple, 1, private)

	logp.Debug("http", "Now sending gap..")

	private, drop := http.GapInStream(tcptuple, 1, 10, private)
	assert.Equal(t, false, drop)

	private = http.ReceivedFin(tcptuple, 1, private)

	trans := expectTransaction(t, http) 
	assert.NotNil(t, trans)
	assert.Equal(t, trans["notes"], []string{"Packet loss while capturing the response"})
}

To check the coverage of your unit tests, run the make cover command at the top of the repository.

Because the main input to Packetbeat are packets and the main output are JSON objects, a convenient way of testing its functionality is by providing PCAP files as input and checking the results in the files created by using the "file" output plugin.

This is the approach taken by the tests in the beats/packetbeat/tests/system directory in the Beats GitHub repository. The tests are written in Python and executed using nose. Here is a simple example test from the MongoDB suite:

    def test_mongodb_find(self):
        """
        Should correctly pass a simple MongoDB find query
        """
        self.render_config_template( 
            mongodb_ports=[27017]
        )
        self.run_packetbeat(pcap="mongodb_find.pcap", 
                            debug_selectors=["mongodb"])

        objs = self.read_output() 
        o = objs[0]
        assert o["type"] == "mongodb"
        assert o["method"] == "find"
        assert o["status"] == "OK"

To run the whole test suite, use:

$ make test

This requires you to have Python and virtualenv installed, but it automatically creates and uses the virtualenv.

To run an individual test, use the following steps:

$ cd tests
$ . env/bin/activate
$ nosetests test_0025_mongodb_basic.py:Test.test_write_errors

After running the individual test, you can check the logs, the output, and the configuration file manually by looking into the folder that the last_run symlink points to:

$ cd last_run
$ ls
output packetbeat.log packetbeat.yml