fix tests with missing kdbx context.

lib/src/kdbx_dao.dart

@@ -10,7 +10,7 @@ extension KdbxDao on KdbxFile {
     @required String name,
   }) {
     assert(parent != null, name != null);
-    final newGroup = KdbxGroup.create(parent: parent, name: name);
+    final newGroup = KdbxGroup.create(ctx: ctx, parent: parent, name: name);
     parent.addGroup(newGroup);
     return newGroup;
   }

lib/src/kdbx_entry.dart

@@ -36,7 +36,7 @@ class KdbxEntry extends KdbxObject {
   KdbxEntry.create(KdbxFile file, KdbxGroup parent)
       : isHistoryEntry = false,
         history = [],
-        super.create(file, 'Entry', parent) {
+        super.create(file.ctx, file, 'Entry', parent) {
     icon.set(KdbxIcon.Key);
   }
 

lib/src/kdbx_format.dart

@@ -305,7 +305,7 @@ class KdbxFormat {
       ctx: ctx,
       generator: generator,
     );
-    final rootGroup = KdbxGroup.create(parent: null, name: name);
+    final rootGroup = KdbxGroup.create(ctx: ctx, parent: null, name: name);
     final body = KdbxBody.create(meta, rootGroup);
     return KdbxFile(
       ctx,

lib/src/kdbx_group.dart

@@ -8,8 +8,12 @@ import 'package:xml/xml.dart';
 import 'kdbx_object.dart';
 
 class KdbxGroup extends KdbxObject {
-  KdbxGroup.create({@required KdbxGroup parent, @required String name})
+  KdbxGroup.create(
+      {@required KdbxReadWriteContext ctx,
+      @required KdbxGroup parent,
+      @required String name})
       : super.create(
+          ctx,
           parent?.file,
           'Group',
           parent,

lib/src/kdbx_object.dart

@@ -71,8 +71,9 @@ abstract class KdbxNode with Changeable<KdbxNode> {
 }
 
 abstract class KdbxObject extends KdbxNode {
-  KdbxObject.create(this.file, String nodeName, KdbxGroup parent)
-      : times = KdbxTimes.create(file.ctx),
+  KdbxObject.create(
+      KdbxReadWriteContext ctx, this.file, String nodeName, KdbxGroup parent)
+      : times = KdbxTimes.create(ctx),
         _parent = parent,
         super.create(nodeName) {
     _uuid.set(KdbxUuid.random());