test: add unit tests for tuple data decoding logic (#87)

* test: add unit tests for tuple data decoding logic

Signed-off-by: Haluk Muhsin Karakoç <haluk_karakoc@hotmail.com>

* fix(test): resolve linter errors (require usage & imports)

Signed-off-by: Haluk Muhsin KARAKOÇ <h.karakoc@simeranya.com.tr>
Signed-off-by: Haluk Muhsin Karakoç <haluk_karakoc@hotmail.com>

---------

Signed-off-by: Haluk Muhsin Karakoç <haluk_karakoc@hotmail.com>
Signed-off-by: Haluk Muhsin KARAKOÇ <h.karakoc@simeranya.com.tr>

Author: karakoc49

pq/message/tuple/data_test.go

@@ -0,0 +1,107 @@
+package tuple
+
+import (
+	"encoding/binary"
+	"testing"
+
+	"github.com/jackc/pgx/v5/pgtype"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestNewData(t *testing.T) {
+	tupleDataType := uint8('D')
+
+	// Payload construction
+	buf := []byte{}
+	// Skip bytes (simulated garbage or other headers)
+	skipBytes := []byte{0x00}
+	buf = append(buf, skipBytes...)
+
+	// Tuple Data Type
+	buf = append(buf, tupleDataType)
+
+	// Column count (2)
+	colCount := make([]byte, 2)
+	binary.BigEndian.PutUint16(colCount, 2)
+	buf = append(buf, colCount...)
+
+	// Col 1: Text 't'
+	buf = append(buf, DataTypeText)
+	// Col 1 Length: 5 ("value")
+	lenBuf := make([]byte, 4)
+	binary.BigEndian.PutUint32(lenBuf, 5)
+	buf = append(buf, lenBuf...)
+	// Col 1 Data
+	buf = append(buf, []byte("value")...)
+
+	// Col 2: Null 'n'
+	buf = append(buf, DataTypeNull)
+
+	t.Run("should parse valid data", func(t *testing.T) {
+		d, err := NewData(buf, tupleDataType, len(skipBytes))
+		require.NoError(t, err)
+		assert.NotNil(t, d)
+		assert.Equal(t, uint16(2), d.ColumnNumber)
+		assert.Len(t, d.Columns, 2)
+
+		assert.Equal(t, DataTypeText, d.Columns[0].DataType)
+		assert.Equal(t, uint32(5), d.Columns[0].Length)
+		assert.Equal(t, []byte("value"), d.Columns[0].Data)
+
+		assert.Equal(t, DataTypeNull, d.Columns[1].DataType)
+	})
+
+	t.Run("should return error for invalid tuple data type", func(t *testing.T) {
+		_, err := NewData(buf, 'X', len(skipBytes)) // Expecting 'X', but got 'D'
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "invalid tuple data type: D")
+	})
+}
+
+func TestData_DecodeWithColumn(t *testing.T) {
+	tupleDataType := uint8('D')
+	buf := []byte{}
+	buf = append(buf, tupleDataType) // No skip bytes this time for simplicity
+
+	// Column count (2)
+	colCount := make([]byte, 2)
+	binary.BigEndian.PutUint16(colCount, 2)
+	buf = append(buf, colCount...)
+
+	// Col 1: Text 't' - Int value "123"
+	buf = append(buf, DataTypeText)
+	lenBuf := make([]byte, 4)
+	binary.BigEndian.PutUint32(lenBuf, 3)
+	buf = append(buf, lenBuf...)
+	buf = append(buf, []byte("123")...)
+
+	// Col 2: Null 'n'
+	buf = append(buf, DataTypeNull)
+
+	d, _ := NewData(buf, tupleDataType, 0)
+
+	t.Run("should decode columns correctly", func(t *testing.T) {
+		relationColumns := []RelationColumn{
+			{Name: "id", DataType: pgtype.Int4OID},
+			{Name: "description", DataType: pgtype.TextOID},
+		}
+
+		decoded, err := d.DecodeWithColumn(relationColumns)
+		require.NoError(t, err)
+		assert.NotNil(t, decoded)
+		assert.Equal(t, int32(123), decoded["id"])
+		assert.Nil(t, decoded["description"])
+	})
+
+	t.Run("should use string fallback for unknown types", func(t *testing.T) {
+		relationColumns := []RelationColumn{
+			{Name: "unknown_col", DataType: 999999}, // Unknown OID
+			{Name: "description", DataType: pgtype.TextOID},
+		}
+
+		decoded, err := d.DecodeWithColumn(relationColumns)
+		require.NoError(t, err)
+		assert.Equal(t, "123", decoded["unknown_col"]) // Fallback to string
+	})
+}