Make GitHub.auth non-nullable (#377)

* add const everywhere

example/index.dart

@@ -3,7 +3,7 @@ import 'common.dart';
 
 void main() {
   final tokenInput = querySelector('#token') as InputElement;
-  tokenInput.value = github.auth!.token ?? '';
+  tokenInput.value = github.auth.token ?? '';
   window.sessionStorage['GITHUB_TOKEN'] = tokenInput.value!;
   tokenInput.onKeyUp.listen((_) {
     window.sessionStorage['GITHUB_TOKEN'] = tokenInput.value!;

example/user_info.dart

@@ -59,8 +59,8 @@ void loadUser() {
     });
   });
 
-  if (github.auth!.token != null) {
-    localToken!.value = github.auth!.token;
+  if (github.auth.token != null) {
+    localToken!.value = github.auth.token;
     loadBtn.click();
   }
 }

lib/src/browser/xplat_browser.dart

@@ -11,7 +11,7 @@ Authentication findAuthenticationFromEnvironment() {
   // search the query string parameters first
   var auth = findAuthenticationInMap(_parseQuery(window.location.href));
   auth ??= findAuthenticationInMap(window.sessionStorage);
-  return auth ?? Authentication.anonymous();
+  return auth ?? const Authentication.anonymous();
 }
 
 /// Parse the query string to a parameter `Map`

lib/src/common/github.dart

@@ -19,12 +19,11 @@ class GitHub {
   /// [endpoint] is the api endpoint to use
   /// [auth] is the authentication information
   GitHub({
-    Authentication? auth,
+    this.auth = const Authentication.anonymous(),
     this.endpoint = 'https://api.github.com',
     this.version = '2022-11-28',
     http.Client? client,
-  })  : auth = auth ?? Authentication.anonymous(),
-        client = client ?? http.Client();
+  }) : client = client ?? http.Client();
 
   static const _ratelimitLimitHeader = 'x-ratelimit-limit';
   static const _ratelimitResetHeader = 'x-ratelimit-reset';
@@ -34,7 +33,7 @@ class GitHub {
   static const versionHeader = 'X-GitHub-Api-Version';
 
   /// Authentication Information
-  Authentication? auth;
+  final Authentication auth;
 
   /// API Endpoint
   final String endpoint;
@@ -369,16 +368,16 @@ class GitHub {
       headers['Accept'] = preview;
     }
 
-    if (auth!.isToken) {
-      headers.putIfAbsent('Authorization', () => 'token ${auth!.token}');
-    } else if (auth!.isBasic) {
+    if (auth.isToken) {
+      headers.putIfAbsent('Authorization', () => 'token ${auth.token}');
+    } else if (auth.isBasic) {
       final userAndPass =
-          base64Encode(utf8.encode('${auth!.username}:${auth!.password}'));
+          base64Encode(utf8.encode('${auth.username}:${auth.password}'));
       headers.putIfAbsent('Authorization', () => 'basic $userAndPass');
     }
 
     // See https://docs.github.com/en/rest/overview/resources-in-the-rest-api?apiVersion=2022-11-28#user-agent-required
-    headers.putIfAbsent('User-Agent', () => auth?.username ?? 'github.dart');
+    headers.putIfAbsent('User-Agent', () => auth.username ?? 'github.dart');
 
     if (method == 'PUT' && body == null) {
       headers.putIfAbsent('Content-Length', () => '0');
@@ -493,10 +492,6 @@ class GitHub {
   /// Disposes of this GitHub Instance.
   /// No other methods on this instance should be called after this method is called.
   void dispose() {
-    // Destroy the Authentication Information
-    // This is needed for security reasons.
-    auth = null;
-
     // Closes the HTTP Client
     client.close();
   }

lib/src/common/util/auth.dart

@@ -10,12 +10,12 @@ class Authentication {
   final String? password;
 
   /// Creates an [Authentication] instance that uses the specified OAuth2 [token].
-  Authentication.withToken(this.token)
+  const Authentication.withToken(this.token)
       : username = null,
         password = null;
 
   /// Creates an [Authentication] instance that has no authentication.
-  Authentication.anonymous()
+  const Authentication.anonymous()
       : token = null,
         username = null,
         password = null;

lib/src/common/xplat_common.dart

@@ -10,7 +10,7 @@ import 'package:github/src/common.dart';
 /// In both contexts it delegates to [findAuthenticationInMap] to find the
 /// github token or username and password.
 Authentication findAuthenticationFromEnvironment() =>
-    Authentication.anonymous();
+    const Authentication.anonymous();
 
 /// Checks the passed in map for keys in [COMMON_GITHUB_TOKEN_ENV_KEYS].
 /// The first one that exists is used as the github token to call [Authentication.withToken] with.

lib/src/server/xplat_server.dart

@@ -27,5 +27,5 @@ Authentication findAuthenticationFromEnvironment() {
   }
 
   return findAuthenticationInMap(Platform.environment) ??
-      Authentication.anonymous();
+      const Authentication.anonymous();
 }

test/common/github_test.dart

@@ -1,6 +1,6 @@
 import 'dart:io';
 
-import 'package:github/src/common/github.dart';
+import 'package:github/src/common.dart';
 import 'package:http/http.dart';
 import 'package:http/testing.dart';
 import 'package:test/test.dart';
@@ -38,5 +38,22 @@ void main() {
       final userAgent = request!.headers['User-Agent'];
       expect(userAgent, 'github.dart');
     });
+
+    test('anonymous auth passes no authorization header', () async {
+      Request? request;
+      final client = MockClient((r) async {
+        request = r;
+        return Response('{}', HttpStatus.ok);
+      });
+
+      final github = GitHub(
+        client: client,
+        auth: const Authentication.anonymous(),
+      );
+      await github.getJSON(''); // Make HTTP request
+
+      expect(request, isNotNull);
+      expect(request!.headers.containsKey('Authorization'), isFalse);
+    });
   });
 }

test/experiment/crawler.dart

@@ -1,7 +1,7 @@
 import 'package:github/github.dart';
 
 void main() {
-  final github = GitHub(auth: Authentication.anonymous());
+  final github = GitHub(auth: const Authentication.anonymous());
 
   final crawler = RepositoryCrawler(
     github,

test/git_test.dart

@@ -10,8 +10,8 @@ const date = '2014-10-02T15:21:29Z';
 GitHub createGithub() {
   return GitHub(
       endpoint: fakeApiUrl,
-      auth:
-          Authentication.withToken('0000000000000000000000000000000000000001'));
+      auth: const Authentication.withToken(
+          '0000000000000000000000000000000000000001'));
 }
 
 void main() {

test/scenarios_test.dart

@@ -28,8 +28,8 @@ Future<GitHub> createGithubWithScenario(String scenario,
   var j = json.decode(resp.body);
   return GitHub(
       endpoint: j['url'],
-      auth:
-          Authentication.withToken('0000000000000000000000000000000000000001'));
+      auth: const Authentication.withToken(
+          '0000000000000000000000000000000000000001'));
 }
 
 /// Run scenario tests against ockokits fixtures-server