Add support for get in set command 207

integration_tests/commands/resp/set_test.go

@@ -48,6 +48,106 @@ func TestSet(t *testing.T) {
 		})
 	}
 }
+func TestSetWithGetOption(t *testing.T) {
+	conn := getLocalConnection()
+	expiryTime := strconv.FormatInt(time.Now().Add(1*time.Minute).UnixMilli(), 10) // For PXAT expiry
+	defer conn.Close()
+
+	testCases := []TestCase{
+		{
+			name:     "Set with GET on Existing Key",
+			commands: []string{"SET k old_value", "SET k new_value GET", "GET k"},
+			expected: []interface{}{"OK", "old_value", "new_value"},
+		},
+		{
+			name:     "Set with GET on Non-Existent Key",
+			commands: []string{"SET k new_value GET", "GET k"},
+			expected: []interface{}{"(nil)", "new_value"},
+		},
+		{
+			name:     "Set with GET and NX on Non-Existent Key",
+			commands: []string{"DEL k", "SET k new_value NX GET", "GET k"},
+			expected: []interface{}{int64(0), "(nil)", "new_value"},
+		},
+		{
+			name:     "Bitwise Set and Retrieve with GET",
+			commands: []string{"SETBIT k 1 1", "GET k", "SET k val GET"},
+			expected: []interface{}{int64(0), "@", "@"},
+		},
+		{
+			name:     "Set with GET and NX on Existing Key",
+			commands: []string{"SET k old_value", "SET k new_value NX GET", "GET k"},
+			expected: []interface{}{"OK", "(nil)", "old_value"},
+		},
+		{
+			name:     "Set with GET and XX on Existing Key",
+			commands: []string{"SET k old_value", "SET k new_value XX GET", "GET k"},
+			expected: []interface{}{"OK", "old_value", "new_value"},
+		},
+		{
+			name:     "Set with GET and XX on Non-Existent Key",
+			commands: []string{"SET k new_value XX GET", "GET k"},
+			expected: []interface{}{"(nil)", "(nil)"},
+		},
+		{
+			name:     "Set with GET and Expiry EX option",
+			commands: []string{"SET k old_value", "SET k new_value GET EX 2", "GET k", "SLEEP 3", "GET k"},
+			expected: []interface{}{"OK", "old_value", "new_value", "OK", "(nil)"},
+		},
+		{
+			name:     "Set with GET and Expiry PX option",
+			commands: []string{"SET k old_value", "SET k new_value GET PX 2000", "GET k", "SLEEP 3", "GET k"},
+			expected: []interface{}{"OK", "old_value", "new_value", "OK", "(nil)"},
+		},
+		{
+			name:     "Set with GET and Expiry PXAT option",
+			commands: []string{"SET k old_value", "SET k new_value GET PXAT " + expiryTime, "GET k"},
+			expected: []interface{}{"OK", "old_value", "new_value"},
+		},
+		{
+			name:     "Set with GET and Invalid PXAT timestamp",
+			commands: []string{"SET k new_value GET PXAT 123123", "GET k"},
+			expected: []interface{}{"(nil)", "(nil)"},
+		},
+		{
+			name:     "Set with GET and KEEPTTL",
+			commands: []string{"SET k old_value EX 5", "SET k new_value GET KEEPTTL", "GET k"},
+			expected: []interface{}{"OK", "old_value", "new_value"},
+		},
+		// Edge cases
+		{
+			name:     "Set with GET and Both EX and PX options",
+			commands: []string{"SET k new_value GET EX 2 PX 2000"},
+			expected: []interface{}{"ERR syntax error"},
+		},
+		{
+			name:     "Set with GET and NX on an Already Existing Key",
+			commands: []string{"DEL k", "SET k existing_value", "SET k new_value NX GET", "GET k"},
+			expected: []interface{}{int64(0), "OK", "(nil)", "existing_value"},
+		},
+		{
+			name:     "Set with GET and XX on a Non-Existent Key",
+			commands: []string{"DEL k", "SET k new_value XX GET", "GET k"},
+			expected: []interface{}{int64(0), "(nil)", "(nil)"},
+		},
+		{
+			name:     "Set with GET and NX followed by XX",
+			commands: []string{"SET k first_value NX GET", "SET k second_value XX GET", "GET k"},
+			expected: []interface{}{"(nil)", "first_value", "second_value"},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			// Clean up keys before each test
+			FireCommand(conn, "DEL k")
+			for i, cmd := range tc.commands {
+				result := FireCommand(conn, cmd)
+				assert.Equal(t, tc.expected[i], result)
+			}
+		})
+	}
+}
 
 func TestSetWithOptions(t *testing.T) {
 	conn := getLocalConnection()

internal/eval/store_eval.go

@@ -44,6 +44,8 @@ func evalSET(args []string, store *dstore.Store) *EvalResponse {
 	var exDurationMs int64 = -1
 	var state exDurationState = Uninitialized
 	var keepttl bool = false
+	var isGetCmdPresent bool = false
+	var getResp *EvalResponse
 
 	key, value = args[0], args[1]
 	oType, oEnc := deduceTypeEncoding(value)
@@ -149,6 +151,13 @@ func evalSET(args []string, store *dstore.Store) *EvalResponse {
 			}
 		case KeepTTL:
 			keepttl = true
+		case GET:
+			isGetCmdPresent = true
+			getResp = evalGET([]string{key}, store)
+			// Abort SET operation if it has error
+			if getResp.Error != nil {
+				return getResp
+			}
 		default:
 			return &EvalResponse{
 				Result: nil,
@@ -174,6 +183,9 @@ func evalSET(args []string, store *dstore.Store) *EvalResponse {
 	// putting the k and value in a Hash Table
 	store.Put(key, store.NewObj(storedValue, exDurationMs, oType, oEnc), dstore.WithKeepTTL(keepttl))
 
+	if isGetCmdPresent {
+		return getResp
+	}
 	return &EvalResponse{
 		Result: clientio.OK,
 		Error:  nil,