✅ ++

dio/test/basic_test.dart

@@ -8,56 +8,6 @@ import 'mock/adapters.dart';
 import 'utils.dart';
 
 void main() {
-  group(Headers, () {
-    test('set', () {
-      final headers = Headers.fromMap({
-        'set-cookie': ['k=v', 'k1=v1'],
-        'content-length': ['200'],
-        'test': ['1', '2'],
-      });
-      headers.add('SET-COOKIE', 'k2=v2');
-      expect(headers.value('content-length'), '200');
-      expect(Future(() => headers.value('test')), throwsException);
-      expect(headers['set-cookie']?.length, 3);
-      headers.remove('set-cookie', 'k=v');
-      expect(headers['set-cookie']?.length, 2);
-      headers.removeAll('set-cookie');
-      expect(headers['set-cookie'], isNull);
-      final ls = [];
-      headers.forEach((k, list) => ls.addAll(list));
-      expect(ls.length, 3);
-      expect(headers.toString(), 'content-length: 200\ntest: 1\ntest: 2\n');
-      headers.set('content-length', '300');
-      expect(headers.value('content-length'), '300');
-      headers.set('content-length', ['400']);
-      expect(headers.value('content-length'), '400');
-    });
-
-    test('clear', () {
-      final headers1 = Headers();
-      headers1.set('xx', 'v');
-      expect(headers1.value('xx'), 'v');
-      headers1.clear();
-      expect(headers1.map.isEmpty, isTrue);
-    });
-
-    test('case-sensitive', () {
-      final headers = Headers.fromMap(
-        {
-          'SET-COOKIE': ['k=v', 'k1=v1'],
-          'content-length': ['200'],
-          'Test': ['1', '2'],
-        },
-        caseSensitive: true,
-      );
-      expect(headers['SET-COOKIE']?.length, 2);
-      // Although it's case-sensitive, we still use case-insensitive map.
-      expect(headers['set-cookie']?.length, 2);
-      expect(headers['content-length']?.length, 1);
-      expect(headers['Test']?.length, 2);
-    });
-  });
-
   test('send with an invalid URL', () async {
     await expectLater(
       Dio().get('http://http.invalid'),

dio/test/headers_test.dart

@@ -0,0 +1,56 @@
+import 'dart:async';
+
+import 'package:dio/dio.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group(Headers, () {
+    test('set', () {
+      final headers = Headers.fromMap({
+        'set-cookie': ['k=v', 'k1=v1'],
+        'content-length': ['200'],
+        'test': ['1', '2'],
+      });
+      headers.add('SET-COOKIE', 'k2=v2');
+      expect(headers.value('content-length'), '200');
+      expect(Future(() => headers.value('test')), throwsException);
+      expect(headers['set-cookie']?.length, 3);
+      headers.remove('set-cookie', 'k=v');
+      expect(headers['set-cookie']?.length, 2);
+      headers.removeAll('set-cookie');
+      expect(headers['set-cookie'], isNull);
+      final ls = [];
+      headers.forEach((k, list) => ls.addAll(list));
+      expect(ls.length, 3);
+      expect(headers.toString(), 'content-length: 200\ntest: 1\ntest: 2\n');
+      headers.set('content-length', '300');
+      expect(headers.value('content-length'), '300');
+      headers.set('content-length', ['400']);
+      expect(headers.value('content-length'), '400');
+    });
+
+    test('clear', () {
+      final headers1 = Headers();
+      headers1.set('xx', 'v');
+      expect(headers1.value('xx'), 'v');
+      headers1.clear();
+      expect(headers1.map.isEmpty, isTrue);
+    });
+
+    test('case-sensitive', () {
+      final headers = Headers.fromMap(
+        {
+          'SET-COOKIE': ['k=v', 'k1=v1'],
+          'content-length': ['200'],
+          'Test': ['1', '2'],
+        },
+        caseSensitive: true,
+      );
+      expect(headers['SET-COOKIE']?.length, 2);
+      // Although it's case-sensitive, we still use case-insensitive map.
+      expect(headers['set-cookie']?.length, 2);
+      expect(headers['content-length']?.length, 1);
+      expect(headers['Test']?.length, 2);
+    });
+  });
+}

dio/test/options_test.dart

@@ -1,8 +1,14 @@
 @TestOn('vm')
+import 'dart:io';
+
 import 'package:dio/dio.dart';
+import 'package:dio/io.dart';
+import 'package:mockito/mockito.dart';
 import 'package:test/test.dart';
 
 import 'mock/adapters.dart';
+import 'mock/http_mock.dart';
+import 'mock/http_mock.mocks.dart';
 import 'utils.dart';
 
 void main() {
@@ -477,4 +483,32 @@ void main() {
       expect(response.data, 'test');
     }
   });
+
+  test('Headers can be case-sensitive', () async {
+    await HttpOverrides.runWithHttpOverrides(() async {
+      final client = MockHttpClient();
+      final dio = Dio();
+      dio.httpClientAdapter = IOHttpClientAdapter(
+        createHttpClient: () => client,
+      );
+
+      late MockHttpClientRequest request;
+      when(client.openUrl(any, any)).thenAnswer((_) async {
+        request = MockHttpClientRequest();
+        return request;
+      });
+      await dio.get(
+        'https://pub.dev',
+        options: Options(
+          caseSensitiveHeaders: true,
+          headers: {
+            'Sensitive': 'foo-1',
+            'insensitive': 'foo-2',
+          },
+        ),
+      );
+      expect(request.headers.value('Sensitive'), 'foo-1');
+      expect(request.headers.value('insensitive'), 'foo-2');
+    }, MockHttpOverrides());
+  });
 }