hscontrol/types: silence zerolog by default in tests

Tests were dumping megabytes of zerolog output on failure; silence
at init and let individual tests opt in via SetGlobalLevel when they need
log-driven assertions.

Updates #3157

hscontrol/types/testlog.go

@@ -0,0 +1,48 @@
+package types
+
+import (
+	"os"
+	"testing"
+
+	"github.com/rs/zerolog"
+)
+
+// EnvTestLogLevel overrides the default test log level. Accepts any zerolog
+// level string: trace, debug, info, warn, error, fatal, panic, disabled.
+const EnvTestLogLevel = "HEADSCALE_TEST_LOG_LEVEL"
+
+// init quiets zerolog when this package is loaded inside a test binary.
+//
+// hscontrol/types is transitively imported by every test in the repo that
+// emits zerolog output, so this init() runs once per test binary and is
+// the only place that needs to know about test logging configuration.
+//
+// Default: ErrorLevel (silent in green-path runs, real errors still surface).
+// Override: HEADSCALE_TEST_LOG_LEVEL=debug (or trace, info, warn, disabled).
+//
+// Production binaries are unaffected because testing.Testing() returns false
+// outside of test execution. The same testing.Testing() pattern is already
+// used in hscontrol/db/users.go and hscontrol/db/node.go, so importing the
+// testing package here is consistent with existing project conventions.
+//
+// Pitfalls:
+//   - log.Fatal still calls os.Exit and log.Panic still panics regardless of
+//     level — only the rendered message is suppressed.
+//   - Local buffer loggers (zerolog.New(&buf)) are also gated by the global
+//     level. Tests that assert on log output (currently only
+//     hscontrol/util/zlog) re-enable trace level via their own init_test.go.
+func init() {
+	if !testing.Testing() {
+		return
+	}
+
+	if raw := os.Getenv(EnvTestLogLevel); raw != "" {
+		lvl, err := zerolog.ParseLevel(raw)
+		if err == nil {
+			zerolog.SetGlobalLevel(lvl)
+			return
+		}
+	}
+
+	zerolog.SetGlobalLevel(zerolog.ErrorLevel)
+}