Created writer mock.

Created mock server.
Added test for ping command plugin.

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()))
+		}
+	}
+}