snapshot of https://github.com/nats-io/nats-server.git (main, 2026-09-15; blobs > 131072B omitted)

server/feature_flags_test.go

@@ -0,0 +1,69 @@
+// Copyright 2026 The NATS Authors
+// 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 server
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestGetFeatureFlag(t *testing.T) {
+	featureFlags["test_flag"] = true
+	t.Cleanup(func() { delete(featureFlags, "test_flag") })
+
+	// Unset feature flags gets defaults.
+	o := &Options{}
+	require_Equal(t, o.getFeatureFlag(""), false)
+	require_Equal(t, o.getFeatureFlag("test_flag"), true)
+
+	// User disables the feature flag, it takes precedence.
+	o.FeatureFlags = map[string]bool{"test_flag": false}
+	require_Equal(t, o.getFeatureFlag("test_flag"), false)
+
+	// User enables the feature flag, but we don't support it anymore.
+	// It's allowed for the user to provide stale flags, but we shouldn't return they're enabled.
+	delete(featureFlags, "test_flag")
+	o.FeatureFlags = map[string]bool{"test_flag": true}
+	require_Equal(t, o.getFeatureFlag("test_flag"), false)
+}
+
+func TestFeatureFlagsConfigParseNonBool(t *testing.T) {
+	conf := createConfFile(t, []byte(`
+		feature_flags {
+		    opt_in_flag: "true"
+		}
+	`))
+
+	_, err := ProcessConfigFile(conf)
+	require_Error(t, err)
+	require_Contains(t, err.Error(), `error parsing feature flag "opt_in_flag": expected bool, got string`)
+}
+
+func TestGetMergedFeatureFlags(t *testing.T) {
+	previous := featureFlags
+	featureFlags = make(map[string]bool)
+	featureFlags["test_flag"] = true
+	featureFlags["test_flag_default"] = true
+	t.Cleanup(func() { featureFlags = previous })
+
+	o := &Options{}
+	o.FeatureFlags = map[string]bool{"test_flag": false, "unknown_flag": false}
+
+	// The merged flags should only contain known flags, with the user's values taking precedence.
+	merged := o.getMergedFeatureFlags()
+	expected := map[string]bool{"test_flag": false, "test_flag_default": true}
+	if !reflect.DeepEqual(expected, merged) {
+		t.Fatalf("Feature flags are incorrect.\nexpected: %+v\ngot: %+v", expected, merged)
+	}
+}