add testing/pgruntime

Testing pgruntime has quickly turned out to be a nightmare, because so
many parts of the test logic are not easily reproducible (e.g.
`stopDBIfLingering`). I decided to not waste a bunch of time testing
code that is relatively compact and easy to verify by careful
examination, and that is unlikely to change a lot in the future.

4 files changed, 14 insertions, 24 deletions

diff --git a/pgruntime/connector.go b/pgruntime/connector.go
index 92780f6..5276a26 100644
--- a/pgruntime/connector.go
+++ b/pgruntime/connector.go
@@ -164,10 +164,12 @@ func resetTestDatabase(ctx context.Context, db gsql.Handle, params testSetupPara
 	}
 
 	// truncate all tables at once
-	query = fmt.Sprintf(`TRUNCATE %s RESTART IDENTITY CASCADE`, strings.Join(quotedTableNames, ", "))
-	_, err = execQuery(ctx, db, query, nil)
-	if err != nil {
-		return fmt.Errorf("during %s: %w", query, err)
+	if len(quotedTableNames) > 0 {
+		query = fmt.Sprintf(`TRUNCATE %s RESTART IDENTITY CASCADE`, strings.Join(quotedTableNames, ", "))
+		_, err = execQuery(ctx, db, query, nil)
+		if err != nil {
+			return fmt.Errorf("during %s: %w", query, err)
+		}
 	}
 
 	return nil
diff --git a/pgruntime/main_test.go b/pgruntime/main_test.go
deleted file mode 100644
index db6b0ac..0000000
--- a/pgruntime/main_test.go
+++ /dev/null
@@ -1,14 +0,0 @@
-// SPDX-FileCopyrightText: 2026 Stefan Majewsky <majewsky@gmx.net>
-// SPDX-License-Identifier: Apache-2.0
-
-package pgruntime_test
-
-import (
-	"testing"
-
-	"go.xyrillian.de/gg/pgruntime"
-)
-
-func TestMain(m *testing.M) {
-	pgruntime.WithTestDB(m, m.Run)
-}
diff --git a/pgruntime/pgruntime.go b/pgruntime/pgruntime.go
index 17a6c94..0283eaa 100644
--- a/pgruntime/pgruntime.go
+++ b/pgruntime/pgruntime.go
@@ -20,12 +20,10 @@
 // This is a clean-room reimplementation of one half of [easypg] with several interface improvements and cleanups, most notably:
 //   - The hard dependency on lib/pq has been removed.
 //   - Support for creating databases on first use has been removed (except in ConnectForTest).
-//   - ConnectForTest now recreates databases instead of just wiping their contents.
+//   - The reset logic in ConnectForTest is completely reworked and massively simplified.
 //
 // [easypg]: https://pkg.go.dev/github.com/sapcc/go-bits/easypg
 // [lib/pq]: https://pkg.go.dev/github.com/lib/pq
 // [pgx]: https://pkg.go.dev/github.com/jackc/pgx/v5
 // [gg-pgx]: https://git.xyrillian.de/go-gg-pgx/
 package pgruntime
-
-// TODO: test coverage via separate module importing github.com/lib/pq
diff --git a/pgruntime/testdb.go b/pgruntime/testdb.go
index 261f88a..808784c 100644
--- a/pgruntime/testdb.go
+++ b/pgruntime/testdb.go
@@ -69,8 +69,7 @@ func WithTestDB(m *testing.M, action func() int) int {
 	if err == nil {
 		return result
 	} else {
-		fmt.Fprintln(os.Stderr, err.Error())
-		return 1
+		panic(err.Error())
 	}
 }
 
@@ -135,7 +134,12 @@ func findTestdbPath() (string, error) {
 
 	// if there is an override path, report the override path (so that initDBIfNecessary can create it),
 	// but put a symlink at the standard path for convenient access
-	return overridePath, os.Symlink(overridePath, testdbPath)
+	err = os.Symlink(overridePath, testdbPath)
+	if os.IsExist(err) {
+		// do not complain if the symlink already exists
+		err = nil
+	}
+	return overridePath, err
 }
 
 func findModuleRootDir(dirPath string) (Option[string], error) {