Test otel instrumentation for panics. (#4582)

This change adds a test that tries to limit runtime panics in staging
by checking some known cases that we encountered
recently. Unfortunately, testing cannot be extensive, but should
prevent us from merging broken PRs from dependabot.

Fixes #4534

internal/db/otel_test.go

@@ -0,0 +1,90 @@
+//
+// Copyright 2024 Stacklok, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package db
+
+import (
+	"database/sql"
+	"os"
+	"testing"
+
+	embeddedpostgres "github.com/fergusstrange/embedded-postgres"
+	"github.com/rs/zerolog/log"
+	"github.com/signalfx/splunk-otel-go/instrumentation/database/sql/splunksql"
+	_ "github.com/signalfx/splunk-otel-go/instrumentation/github.com/lib/pq/splunkpq"
+	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/otel"
+	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
+)
+
+func TestOtelPanic(t *testing.T) {
+	t.Parallel()
+
+	defer func() {
+		if r := recover(); r != nil {
+			t.Errorf(`
+The code did panic. This usually means that some OTEL dependency
+introduced a breaking change or regression that is only detected at
+run time.
+`)
+		}
+	}()
+
+	tmpName, err := os.MkdirTemp("", "minder-db-test")
+	require.NoError(t, err)
+	defer func() {
+		if err := os.RemoveAll(tmpName); err != nil {
+			log.Err(err).Msg("cannot remove tmpdir")
+		}
+	}()
+
+	dbCfg := embeddedpostgres.DefaultConfig().
+		Database("minder").
+		RuntimePath(tmpName).
+		Port(5434)
+	postgres := embeddedpostgres.NewDatabase(dbCfg)
+
+	err = postgres.Start()
+	require.NoError(t, err)
+	defer func() {
+		if err := postgres.Stop(); err != nil {
+			log.Err(err).Msg("cannot stop postgres")
+		}
+	}()
+
+	conn1 := connect(t, "postgres", "user=postgres dbname=minder password=postgres host=localhost port=5434 sslmode=disable")
+	require.NotNil(t, conn1)
+	conn2 := connect(t, "postgres", "user=postgres dbname=minder password=postgres host=localhost port=5434 sslmode=disable")
+	require.NotNil(t, conn2)
+
+	reader := sdkmetric.NewManualReader()
+	mp := sdkmetric.NewMeterProvider(
+		sdkmetric.WithReader(reader),
+	)
+	otel.SetMeterProvider(mp)
+}
+
+func connect(t *testing.T, driver string, connStr string) *sql.DB {
+	t.Helper()
+
+	conn, err := splunksql.Open(driver, connStr)
+	require.NotNil(t, conn)
+	require.NoError(t, err)
+
+	_, err = conn.Exec("SELECT 1")
+	require.NoError(t, err)
+
+	return conn
+}