test: start the updates package's Postgres only without -short

go test passes -short as -test.short=true, so scanning os.Args for
-test.short never matched and every -short run started a container (and
failed without Docker). Read the flag through flag.Parse and
testing.Short instead.

updates/postgres_test.go

@@ -3,6 +3,7 @@ package updates
 import (
 	"context"
 	"database/sql"
+	"flag"
 	"fmt"
 	"net/url"
 	"os"
@@ -22,9 +23,13 @@ var (
 	userPGErr error
 )
 
+// TestMain starts the Postgres container only without -short. go test
+// passes -short as -test.short=true, so the flag is read through
+// flag.Parse and testing.Short, never by scanning os.Args.
 func TestMain(m *testing.M) {
+	flag.Parse()
 	code := 1
-	if !testShort() {
+	if !testing.Short() {
 		ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)
 		userPGErr = startUserPostgres(ctx)
 		cancel()
@@ -39,15 +44,6 @@ func TestMain(m *testing.M) {
 	os.Exit(code)
 }
 
-func testShort() bool {
-	for _, a := range os.Args {
-		if a == "-test.short" {
-			return true
-		}
-	}
-	return false
-}
-
 func startUserPostgres(ctx context.Context) error {
 	ctr, err := postgres.Run(ctx,
 		"postgres:16-alpine",