Tests for command `PING`

[arpitbbhayani]

Currently, there are almost no unit tests for the PING command. We need a comprehensive test suite for this command that also checks the correctness and completeness.

1. covers the correctness of single command
2. covers the correctness when multiple commands are fired
3. no commands are dropped abruptly
4. ensure we check for small, large, and massive inputs (if applicable)

[harin-ramesh]

Hi, I will take up this issue.

[harin-ramesh]

Hi, I am getting a connection refused error while running test case, seems like PING commands are properly working.

Below is my code for the test. @arpitbbhayani @rohanverma94

var wg sync.WaitGroup
go runTestServer(&wg)

var b []byte
var buf = bytes.NewBuffer(b)
conn := getLocalConnection()
buf.WriteByte('a')
cmd := fmt.Sprintf("PING")
v := fireCommand(conn, cmd)
if v != "PONG" {
	t.Fail()
}
fmt.Println("====================================")
fmt.Println(v)
fmt.Println("====================================")


cmd = fmt.Sprintf("PING HELLO!")
v = fireCommand(conn, cmd)
if v != "HELLO!" {
	t.Fail()
}
fmt.Println("====================================")
fmt.Println(v)
fmt.Println("====================================")
fireCommand(conn, "ABORT")
wg.Wait()

[rohanverma94]

@HarinRamesh I'll have a look at this in some time!

[rohanverma94]

@HarinRamesh Thanks for reporting this! This is not an issue with PING, but it has to do with the organization of the TestSuite code. The client connection should provide a warmup to disallow any data race with server FD. The insight of this issue is below:

syscall.Listen(serverFD, maxClients)

and

net.Dial("tcp", "localhost:8379")

Both are called concurrently, and you can't predict which one executes first i.e. data race, it is a nondeterministic behavior

If Dial is called before Listen then there is obviously no listening socket yet and that produces the error.

@arpitbbhayani I propose following change-

//In runTestServer func , return an error channel also
func runTestServer(wg *sync.WaitGroup) error {
	config.IOBufferLength = 16
	config.Port = 8379
	wg.Add(1)
	return server.RunAsyncTCPServer(wg)
}

//In ping_test.go use that error channel to make sure that listen() is called before Dial() 
func TestPING(t *testing.T) {
	var wg sync.WaitGroup
	go func() {
		err := runTestServer(&wg)
		if err != nil {
			conn := getLocalConnection()

			cmd := fmt.Sprintf("PING")
			v := fireCommand(conn, cmd)
			if v != "PONG" {
				t.Fail()
			}
			fmt.Println("====================================")
			fmt.Println(v)
			fmt.Println("====================================")

			cmd = fmt.Sprintf("PING HELLO!")
			v = fireCommand(conn, cmd)
			if v != "HELLO!" {
				t.Fail()
			}
			fmt.Println("====================================")
			fmt.Println(v)
			fmt.Println("====================================")
			fireCommand(conn, "ABORT")
			wg.Done()
		}
	}()

	wg.Wait()
}