diff --git a/lib/configuration_provider.dart b/lib/configuration_provider.dart
index 5e7121c..0682a76 100644
--- a/lib/configuration_provider.dart
+++ b/lib/configuration_provider.dart
@@ -1,4 +1,4 @@
 abstract class ConfigurationProvider {
   bool containsKey(String key);
   String? getOrNull(String key, {String? defaultValue});
-}
\ No newline at end of file
+}
diff --git a/lib/system_config.dart b/lib/system_config.dart
index ee79d07..186fa0d 100644
--- a/lib/system_config.dart
+++ b/lib/system_config.dart
@@ -21,6 +21,6 @@ class SystemConfig {
   }
 
   static String? getOrNull(String key, {String? defaultValue}) {
-    return getProvider().getOrNull(key);
+    return getProvider().getOrNull(key, defaultValue: defaultValue);
   }
 }
diff --git a/pubspec.lock b/pubspec.lock
index 0fb5504..0f5fc71 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -1,6 +1,174 @@
 # Generated by pub
 # See https://dart.dev/tools/pub/glossary#lockfile
 packages:
+  _fe_analyzer_shared:
+    dependency: transitive
+    description:
+      name: _fe_analyzer_shared
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "19.0.0"
+  analyzer:
+    dependency: transitive
+    description:
+      name: analyzer
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.3.0"
+  args:
+    dependency: transitive
+    description:
+      name: args
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.0"
+  async:
+    dependency: transitive
+    description:
+      name: async
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.5.0"
+  boolean_selector:
+    dependency: transitive
+    description:
+      name: boolean_selector
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.1.0"
+  charcode:
+    dependency: transitive
+    description:
+      name: charcode
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.0"
+  cli_util:
+    dependency: transitive
+    description:
+      name: cli_util
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.3.0"
+  collection:
+    dependency: transitive
+    description:
+      name: collection
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.15.0"
+  convert:
+    dependency: transitive
+    description:
+      name: convert
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "3.0.0"
+  coverage:
+    dependency: transitive
+    description:
+      name: coverage
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.2"
+  crypto:
+    dependency: transitive
+    description:
+      name: crypto
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "3.0.0"
+  file:
+    dependency: transitive
+    description:
+      name: file
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "6.1.0"
+  glob:
+    dependency: transitive
+    description:
+      name: glob
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.0"
+  http_multi_server:
+    dependency: transitive
+    description:
+      name: http_multi_server
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "3.0.0"
+  http_parser:
+    dependency: transitive
+    description:
+      name: http_parser
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "4.0.0"
+  io:
+    dependency: transitive
+    description:
+      name: io
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.0"
+  js:
+    dependency: transitive
+    description:
+      name: js
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.6.3"
+  logging:
+    dependency: transitive
+    description:
+      name: logging
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.0"
+  matcher:
+    dependency: transitive
+    description:
+      name: matcher
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.12.10"
+  meta:
+    dependency: transitive
+    description:
+      name: meta
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.3.0"
+  mime:
+    dependency: transitive
+    description:
+      name: mime
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.0"
+  node_preamble:
+    dependency: transitive
+    description:
+      name: node_preamble
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.0"
+  package_config:
+    dependency: transitive
+    description:
+      name: package_config
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.0"
+  path:
+    dependency: transitive
+    description:
+      name: path
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.8.0"
   pedantic:
     dependency: "direct dev"
     description:
@@ -8,5 +176,159 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.11.0"
+  pool:
+    dependency: transitive
+    description:
+      name: pool
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.5.0"
+  pub_semver:
+    dependency: transitive
+    description:
+      name: pub_semver
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.0"
+  shelf:
+    dependency: transitive
+    description:
+      name: shelf
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0"
+  shelf_packages_handler:
+    dependency: transitive
+    description:
+      name: shelf_packages_handler
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "3.0.0"
+  shelf_static:
+    dependency: transitive
+    description:
+      name: shelf_static
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.0"
+  shelf_web_socket:
+    dependency: transitive
+    description:
+      name: shelf_web_socket
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.1"
+  source_map_stack_trace:
+    dependency: transitive
+    description:
+      name: source_map_stack_trace
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.1.0"
+  source_maps:
+    dependency: transitive
+    description:
+      name: source_maps
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.10.10"
+  source_span:
+    dependency: transitive
+    description:
+      name: source_span
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.8.1"
+  stack_trace:
+    dependency: transitive
+    description:
+      name: stack_trace
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.10.0"
+  stream_channel:
+    dependency: transitive
+    description:
+      name: stream_channel
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.1.0"
+  string_scanner:
+    dependency: transitive
+    description:
+      name: string_scanner
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0"
+  term_glyph:
+    dependency: transitive
+    description:
+      name: term_glyph
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.0"
+  test:
+    dependency: "direct main"
+    description:
+      name: test
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.16.8"
+  test_api:
+    dependency: transitive
+    description:
+      name: test_api
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.3.0"
+  test_core:
+    dependency: transitive
+    description:
+      name: test_core
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.3.19"
+  typed_data:
+    dependency: transitive
+    description:
+      name: typed_data
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.3.0"
+  vm_service:
+    dependency: transitive
+    description:
+      name: vm_service
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "6.1.0+1"
+  watcher:
+    dependency: transitive
+    description:
+      name: watcher
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.0"
+  web_socket_channel:
+    dependency: transitive
+    description:
+      name: web_socket_channel
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.0"
+  webkit_inspection_protocol:
+    dependency: transitive
+    description:
+      name: webkit_inspection_protocol
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.0"
+  yaml:
+    dependency: transitive
+    description:
+      name: yaml
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "3.1.0"
 sdks:
   dart: ">=2.12.0 <3.0.0"
diff --git a/pubspec.yaml b/pubspec.yaml
index 99155de..4ffc547 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -6,8 +6,8 @@ description: A simple command-line application.
 environment:
   sdk: '>=2.12.0 <3.0.0'
 
-#dependencies:
-#  path: ^1.7.0
+dependencies:
+  test: ^1.16.8
 
 dev_dependencies:
   pedantic: ^1.9.0
diff --git a/test/config_test.dart b/test/config_test.dart
index e69de29..a0ef06c 100644
--- a/test/config_test.dart
+++ b/test/config_test.dart
@@ -0,0 +1,13 @@
+import 'package:configurable/system_config.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('get system config by key', () {
+    var key = 'app.name';
+    var value = 'CUBETIQ';
+    var result = SystemConfig.getOrNull(key, defaultValue: value);
+
+    expect(value, equals(result));
+    expect(value, equals(SystemConfig.getOrNull(key)));
+  });
+}