Add unit tests for internal/xsql package to increase test coverage (#1895)

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: asmyasnikov <[email protected]>
Co-authored-by: Aleksey Myasnikov <[email protected]>

Author: Copilot

internal/xsql/conn_helpers_test.go

@@ -3,7 +3,13 @@ package xsql
 import (
 	"context"
 	"database/sql/driver"
+	"testing"
 	"time"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/ydb-platform/ydb-go-sdk/v3/internal/bind"
+	"github.com/ydb-platform/ydb-go-sdk/v3/internal/xsync"
 )
 
 var (
@@ -63,3 +69,170 @@ var (
 		GetIndexColumns(ctx context.Context, tableName string, indexName string) (columns []string, err error)
 	} = (*Conn)(nil)
 )
+
+func TestConn_Engine(t *testing.T) {
+	tests := []struct {
+		name     string
+		engine   Engine
+		expected Engine
+	}{
+		{
+			name:     "QUERY",
+			engine:   QUERY,
+			expected: QUERY,
+		},
+		{
+			name:     "TABLE",
+			engine:   TABLE,
+			expected: TABLE,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			conn := &Conn{
+				processor: tt.engine,
+			}
+			require.Equal(t, tt.expected, conn.Engine())
+		})
+	}
+}
+
+func TestConn_LastUsage(t *testing.T) {
+	conn := &Conn{
+		lastUsage: xsync.NewLastUsage(),
+	}
+
+	// Initially should be zero time
+	lastUsage := conn.LastUsage()
+	require.False(t, lastUsage.IsZero())
+
+	// Start and stop usage
+	done := conn.lastUsage.Start()
+	time.Sleep(10 * time.Millisecond)
+	done()
+
+	// Should have updated time
+	newLastUsage := conn.LastUsage()
+	require.True(t, newLastUsage.After(lastUsage) || newLastUsage.Equal(lastUsage))
+}
+
+func TestConn_GetDatabaseName(t *testing.T) {
+	// We can't easily mock ydbDriver, so this test is covered
+	// by integration tests instead
+	t.Skip("requires full ydbDriver mock")
+}
+
+func TestConn_normalizePath(t *testing.T) {
+	tests := []struct {
+		name       string
+		pathPrefix string
+		tableName  string
+		expected   string
+	}{
+		{
+			name:       "WithPrefix",
+			pathPrefix: "/local",
+			tableName:  "test_table",
+			expected:   "/local/test_table",
+		},
+		{
+			name:       "AlreadyPrefixed",
+			pathPrefix: "/local",
+			tableName:  "/local/test_table",
+			expected:   "/local/test_table",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			conn := &Conn{
+				connector: &Connector{
+					pathNormalizer: bind.TablePathPrefix(tt.pathPrefix),
+				},
+			}
+
+			result := conn.normalizePath(tt.tableName)
+			require.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestConn_Version(t *testing.T) {
+	conn := &Conn{}
+	version, err := conn.Version(context.Background())
+	require.NoError(t, err)
+	require.Equal(t, "default", version)
+}
+
+func TestIsSysDir(t *testing.T) {
+	tests := []struct {
+		name         string
+		databaseName string
+		dirAbsPath   string
+		expected     bool
+	}{
+		{
+			name:         "SysDirExact",
+			databaseName: "/local",
+			dirAbsPath:   "/local/.sys",
+			expected:     true,
+		},
+		{
+			name:         "SysDirSubpath",
+			databaseName: "/local",
+			dirAbsPath:   "/local/.sys/something",
+			expected:     true,
+		},
+		{
+			name:         "SysHealthDirExact",
+			databaseName: "/local",
+			dirAbsPath:   "/local/.sys_health",
+			expected:     true,
+		},
+		{
+			name:         "SysHealthDirSubpath",
+			databaseName: "/local",
+			dirAbsPath:   "/local/.sys_health/metrics",
+			expected:     true,
+		},
+		{
+			name:         "NormalDir",
+			databaseName: "/local",
+			dirAbsPath:   "/local/tables",
+			expected:     false,
+		},
+		{
+			name:         "DifferentDatabase",
+			databaseName: "/local",
+			dirAbsPath:   "/other/.sys",
+			expected:     false,
+		},
+		{
+			name:         "EmptyPath",
+			databaseName: "/local",
+			dirAbsPath:   "",
+			expected:     false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := isSysDir(tt.databaseName, tt.dirAbsPath)
+			require.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestConn_toYdb(t *testing.T) {
+	conn := &Conn{
+		connector: &Connector{
+			bindings: newMockBindings(),
+		},
+	}
+
+	yql, p, err := conn.toYdb("SELECT 1", driver.NamedValue{Name: "p1", Value: 42})
+	require.NoError(t, err)
+	require.NotEmpty(t, yql)
+	require.NotNil(t, p)
+}