Created writer mock.

Created mock server.
Added test for ping command plugin.

server/main.go

@@ -39,8 +39,8 @@ func (server *Server) Lock() {
 	server.data.mu.Lock()
 }
 
-func (Server *Server) Unlock() {
-	Server.data.mu.Unlock()
+func (server *Server) Unlock() {
+	server.data.mu.Unlock()
 }
 
 func (server *Server) GetData(key string) interface{} {

server/plugins/commands/ping/ping_test.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"bufio"
+	"strings"
+	"testing"
+
+	"github.com/kelvinmwinuka/memstore/utils"
+)
+
+func TestHandleCommand(t *testing.T) {
+	server := &utils.MockServer{}
+
+	cw := &utils.CustomWriter{}
+	writer := bufio.NewWriter(cw)
+
+	tests := []struct {
+		cmd      []string
+		expected string
+	}{
+		{[]string{"ping"}, "+PONG\r\n\n"},
+		{[]string{"ping", "Ping Test"}, "+Ping Test\r\n\n"},
+		{[]string{"ping", "Ping Test", "Error"}, "-Error wrong number of arguments for PING command\r\n\n"},
+	}
+
+	for _, tt := range tests {
+		cw.Buf.Reset()
+		Plugin.HandleCommand(tt.cmd, server, writer)
+		if tt.expected != cw.Buf.String() {
+			t.Errorf("Expected %s, Got %s", strings.TrimSpace(tt.expected), strings.TrimSpace(cw.Buf.String()))
+		}
+	}
+}

utils/mock.go

@@ -0,0 +1,51 @@
+package utils
+
+import (
+	"bytes"
+	"io"
+	"sync"
+)
+
+type CustomWriter struct {
+	Buf bytes.Buffer
+}
+
+func (cw *CustomWriter) Write(p []byte) (int, error) {
+	count := 0
+
+	for _, b := range p {
+		cw.Buf.WriteByte(b)
+		count += 1
+	}
+
+	if count != len(p) {
+		return count, io.ErrShortWrite
+	}
+
+	return count, nil
+}
+
+type MockData struct {
+	mu   sync.Mutex
+	data map[string]interface{}
+}
+
+type MockServer struct {
+	data MockData
+}
+
+func (server *MockServer) Lock() {
+	server.data.mu.Lock()
+}
+
+func (server *MockServer) Unlock() {
+	server.data.mu.Unlock()
+}
+
+func (server *MockServer) GetData(key string) interface{} {
+	return server.data.data[key]
+}
+
+func (server *MockServer) SetData(key string, value interface{}) {
+	server.data.data[key] = value
+}