[+] add connRow struct to handle QueryRow() calls, closes #195 (#196

)

* [-] add `connRow` struct to handle `QueryRow()` calls, fixes #195
* [*] prettify code
* [-] fix error return value of `rows.Scan` is not checked (errcheck)

pgxmock.go

@@ -445,10 +445,9 @@ func (er errRow) Scan(...interface{}) error {
 func (c *pgxmock) QueryRow(ctx context.Context, sql string, args ...interface{}) pgx.Row {
 	rows, err := c.Query(ctx, sql, args...)
 	if err != nil {
-		return errRow{err}
+		return errRow{err: err}
 	}
-	_ = rows.Next()
-	return rows
+	return (*connRow)(rows.(*rowSets))
 }
 
 func (c *pgxmock) Exec(ctx context.Context, query string, args ...interface{}) (pgconn.CommandTag, error) {

rows.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgconn"
+	"github.com/jackc/pgx/v5/pgtype"
 )
 
 // CSVColumnParser is a function which converts trimmed csv
@@ -22,6 +23,35 @@ var CSVColumnParser = func(s string) interface{} {
 	return s
 }
 
+// connRow implements the Row interface for Conn.QueryRow.
+type connRow rowSets
+
+func (r *connRow) Scan(dest ...any) (err error) {
+	rows := (*rowSets)(r)
+
+	if rows.Err() != nil {
+		return rows.Err()
+	}
+
+	for _, d := range dest {
+		if _, ok := d.(*pgtype.DriverBytes); ok {
+			rows.Close()
+			return fmt.Errorf("cannot scan into *pgtype.DriverBytes from QueryRow")
+		}
+	}
+
+	if !rows.Next() {
+		if rows.Err() == nil {
+			return pgx.ErrNoRows
+		}
+		return rows.Err()
+	}
+
+	_ = rows.Scan(dest...)
+	rows.Close()
+	return rows.Err()
+}
+
 type rowSets struct {
 	sets     []*Rows
 	RowSetNo int

rows_test.go

@@ -709,3 +709,39 @@ func TestRowsKind(t *testing.T) {
 		}
 	}
 }
+
+// TestConnRow tests the ConnRow interface implementation for Conn.QueryRow.
+func TestConnRow(t *testing.T) {
+	t.Parallel()
+	mock, _ := NewConn()
+	a := assert.New(t)
+
+	// check error case
+	expectedErr := errors.New("error")
+	mock.ExpectQuery("SELECT").WillReturnError(expectedErr)
+	err := mock.QueryRow(context.Background(), "SELECT").Scan(nil)
+	a.ErrorIs(err, expectedErr)
+
+	// check no rows returned case
+	var id int
+	rows := NewRows([]string{"id"})
+	mock.ExpectQuery("SELECT").WillReturnRows(rows)
+	err = mock.QueryRow(context.Background(), "SELECT").Scan(&id)
+	a.ErrorIs(err, pgx.ErrNoRows)
+
+	// check single row returned case
+	rows = NewRows([]string{"id"}).AddRow(1)
+	mock.ExpectQuery("SELECT").WillReturnRows(rows)
+	err = mock.QueryRow(context.Background(), "SELECT").Scan(&id)
+	a.NoError(err)
+	a.Equal(1, id)
+
+	// check multiple rows returned case
+	rows = NewRows([]string{"id"}).AddRow(1).AddRow(42)
+	mock.ExpectQuery("SELECT").WillReturnRows(rows)
+	err = mock.QueryRow(context.Background(), "SELECT").Scan(&id)
+	a.NoError(err)
+	a.Equal(1, id)
+
+	a.NoError(mock.ExpectationsWereMet())
+}