test(resp): add unit tests for PerformRequest and ReplyCommand

resp/reply_test.go

@@ -0,0 +1,54 @@
+package resp
+
+import (
+	"io"
+	"net"
+	"testing"
+)
+
+// TestReplyCommand tests the ReplyCommand function for
+// all possible valid and invalid inputs
+func TestReplyCommand(t *testing.T) {
+	tests := []struct {
+		reply []byte
+		want  string
+	}{
+		{[]byte("+PONG\r\n"), "+PONG\r\n"},
+		{[]byte("+OK\r\n"), "+OK\r\n"},
+		{[]byte("$5\r\nhello\r\n"), "$5\r\nhello\r\n"},
+		{[]byte("-error message\r\n"), "-error message\r\n"},
+	}
+	for _, test := range tests {
+		server, client := net.Pipe()
+
+		ch := make(chan []byte, 1)
+		go func() {
+			b, _ := io.ReadAll(client)
+			ch <- b
+		}()
+
+		ReplyCommand(test.reply, server)
+		server.Close()
+
+		got := string(<-ch)
+		if got != test.want {
+			t.Errorf("ReplyCommand(%q) = %q; want %q", test.reply, got, test.want)
+		}
+		client.Close()
+	}
+}
+
+// TestReplyCommand_ClosedConn tests that ReplyCommand does not panic
+// when the connection is already closed
+func TestReplyCommand_ClosedConn(t *testing.T) {
+	server, client := net.Pipe()
+	client.Close()
+
+	defer func() {
+		if r := recover(); r != nil {
+			t.Errorf("ReplyCommand panicked on closed connection: %v", r)
+		}
+	}()
+	ReplyCommand([]byte("+PONG\r\n"), server)
+	server.Close()
+}

resp/request_test.go

@@ -0,0 +1,62 @@
+package resp
+
+import (
+	"io"
+	"net"
+	"testing"
+)
+
+// newPipe returns a connected pair of net.Conn. server is passed to the function
+// under test; client is used to read back what was written.
+func newPipe(t *testing.T) (server, client net.Conn) {
+	t.Helper()
+	server, client = net.Pipe()
+	t.Cleanup(func() {
+		server.Close()
+		client.Close()
+	})
+	return
+}
+
+// readReply reads from the client side of the pipe in a goroutine and returns
+// the bytes via a channel. The server side must be closed (or the write must
+// complete) before this unblocks.
+func readReply(client net.Conn) <-chan []byte {
+	ch := make(chan []byte, 1)
+	go func() {
+		b, _ := io.ReadAll(client)
+		ch <- b
+	}()
+	return ch
+}
+
+// TestPerformRequest tests the PerformRequest function for
+// all possible valid and invalid inputs
+func TestPerformRequest(t *testing.T) {
+	tests := []struct {
+		input []byte
+		want  string
+	}{
+		// Valid commands
+		{[]byte("*1\r\n$4\r\nPING\r\n"), "+PONG\r\n"},
+		{[]byte("*2\r\n$4\r\nECHO\r\n$5\r\nhello\r\n"), "$5\r\nhello\r\n"},
+		// Invalid RESP prefix
+		{[]byte("%1\r\n$4\r\nPING\r\n"), "-invalid request\r\n"},
+		// Unknown command
+		{[]byte("*1\r\n$3\r\nFOO\r\n"), "-unsupported command\r\n"},
+		// nil buffer — ParseCommand returns zero-value Cmd with empty Name, nothing written
+		{nil, ""},
+	}
+	for _, test := range tests {
+		server, client := newPipe(t)
+		ch := readReply(client)
+
+		PerformRequest(test.input, server)
+		server.Close()
+
+		got := string(<-ch)
+		if got != test.want {
+			t.Errorf("PerformRequest(%q) = %q; want %q", test.input, got, test.want)
+		}
+	}
+}