Use context timeouts in more tests

Tests should timeout in a reasonable time if something is stuck. In
particular this is important when testing deadlock conditions such as
can occur with the copy protocol if both the client and the server are
blocked writing until the other side does a read.

pgtype/hstore_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"reflect"
 	"testing"
+	"time"
 
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
@@ -215,7 +216,10 @@ func TestHstoreCodec(t *testing.T) {
 	pgxtest.RunValueRoundTripTests(context.Background(), t, ctrWithoutCodec, pgxtest.AllQueryExecModes, "hstore", tests)
 
 	// scan empty and NULL: should be different in all query modes
-	pgxtest.RunWithQueryExecModes(context.Background(), t, ctr, pgxtest.AllQueryExecModes, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+
+	pgxtest.RunWithQueryExecModes(ctx, t, ctr, pgxtest.AllQueryExecModes, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
 		h := pgtype.Hstore{"should_be_erased": nil}
 		err := conn.QueryRow(ctx, `select cast(null as hstore)`).Scan(&h)
 		if err != nil {