Add test for mapKeys()

Signed-off-by: Piotr Piotrowski <[email protected]>

collector/collector.go

@@ -408,7 +408,7 @@ func (nc *NATSCollector) objectToMetrics(response map[string]interface{}, namesp
 
 // mapKeys returns a map of all keys in a map, including nested maps.
 // The keys from nested maps are prefixed with the parent key.
-func mapKeys(input map[string]interface{}, prefix string) map[string]struct{} {
+func mapKeys(input map[string]any, prefix string) map[string]struct{} {
 	keys := make(map[string]struct{})
 
 	for k, v := range input {
@@ -417,7 +417,7 @@ func mapKeys(input map[string]interface{}, prefix string) map[string]struct{} {
 			fullKey = prefix + "_" + k
 		}
 
-		if nestedMap, ok := v.(map[string]interface{}); ok {
+		if nestedMap, ok := v.(map[string]any); ok {
 			nestedKeys := mapKeys(nestedMap, fullKey)
 			for nestedKey := range nestedKeys {
 				keys[nestedKey] = struct{}{}

collector/collector_test.go

@@ -15,6 +15,7 @@ package collector
 
 import (
 	"fmt"
+	"maps"
 	"strings"
 	"testing"
 	"time"
@@ -728,3 +729,30 @@ func TestReplicatorMetrics(t *testing.T) {
 	url := "http://127.0.0.1:9922"
 	verifyCollector(ReplicatorSystem, url, "varz", cases, t)
 }
+
+func TestMapKeys(t *testing.T) {
+	m := map[string]any{
+		"foo": "bar",
+		"baz": "quux",
+		"nested": map[string]any{
+			"foo": "bar",
+			"baz": "quux",
+			"nested": map[string]any{
+				"foo": "bar",
+				"baz": "quux",
+			},
+		},
+	}
+	expected := map[string]struct{}{
+		"foo":               {},
+		"baz":               {},
+		"nested_foo":        {},
+		"nested_baz":        {},
+		"nested_nested_foo": {},
+		"nested_nested_baz": {},
+	}
+	keys := mapKeys(m, "")
+	if !maps.Equal(keys, expected) {
+		t.Fatalf("expected %v, got %v", expected, keys)
+	}
+}