Check for method casing

pkgs/http/test/io/client_conformance_test.dart

@@ -10,5 +10,8 @@ import 'package:http_client_conformance_tests/http_client_conformance_tests.dart
 import 'package:test/test.dart';
 
 void main() {
-  testAll(IOClient.new);
+  testAll(IOClient.new,
+      preservesMethodCase:
+          false // https://github.com/dart-lang/sdk/issues/54187
+      );
 }

pkgs/http_client_conformance_tests/lib/http_client_conformance_tests.dart

@@ -51,14 +51,20 @@ export 'src/server_errors_test.dart' show testServerErrors;
 /// If [canWorkInIsolates] is `false` then tests that require that the [Client]
 /// work in Isolates other than the main isolate will be skipped.
 ///
+/// If [preservesMethodCase] is `false` then tests that assume that the
+/// [Client] preserves custom request method casing will be skipped.
+///
 /// The tests are run against a series of HTTP servers that are started by the
 /// tests. If the tests are run in the browser, then the test servers are
 /// started in another process. Otherwise, the test servers are run in-process.
-void testAll(Client Function() clientFactory,
-    {bool canStreamRequestBody = true,
-    bool canStreamResponseBody = true,
-    bool redirectAlwaysAllowed = false,
-    bool canWorkInIsolates = true}) {
+void testAll(
+  Client Function() clientFactory, {
+  bool canStreamRequestBody = true,
+  bool canStreamResponseBody = true,
+  bool redirectAlwaysAllowed = false,
+  bool canWorkInIsolates = true,
+  bool preservesMethodCase = false,
+}) {
   testRequestBody(clientFactory());
   testRequestBodyStreamed(clientFactory(),
       canStreamRequestBody: canStreamRequestBody);
@@ -67,7 +73,7 @@ void testAll(Client Function() clientFactory,
   testResponseBodyStreamed(clientFactory(),
       canStreamResponseBody: canStreamResponseBody);
   testRequestHeaders(clientFactory());
-  testRequestMethods(clientFactory());
+  testRequestMethods(clientFactory(), preservesMethodCase: preservesMethodCase);
   testResponseHeaders(clientFactory());
   testResponseStatusLine(clientFactory());
   testRedirect(clientFactory(), redirectAlwaysAllowed: redirectAlwaysAllowed);

pkgs/http_client_conformance_tests/lib/src/request_methods_tests.dart

@@ -12,7 +12,11 @@ import 'request_methods_server_vm.dart'
 
 /// Tests that the [Client] correctly sends HTTP request methods
 /// (e.g. GET, HEAD).
-void testRequestMethods(Client client) async {
+///
+/// If [preservesMethodCase] is `false` then tests that assume that the
+/// [Client] preserves custom request method casing will be skipped.
+void testRequestMethods(Client client,
+    {bool preservesMethodCase = true}) async {
   group('request methods', () {
     late final String host;
     late final StreamChannel<Object?> httpServerChannel;
@@ -25,15 +29,27 @@ void testRequestMethods(Client client) async {
     });
     tearDownAll(() => httpServerChannel.sink.add(null));
 
-    test('custom method', () async {
+    test('custom method - not case preserving', () async {
       await client.send(Request(
-        'CUSTOM',
+        'CuStOm',
         Uri.http(host, ''),
       ));
       final method = await httpServerQueue.next as String;
-      expect('CUSTOM', method);
+      expect('CUSTOM', method.toUpperCase());
     });
 
+    test('custom method case preserving', () async {
+      await client.send(Request(
+        'CuStOm',
+        Uri.http(host, ''),
+      ));
+      final method = await httpServerQueue.next as String;
+      expect('CuStOm', method);
+    },
+        skip: preservesMethodCase
+            ? false
+            : 'does not preserve HTTP request method case');
+
     test('delete', () async {
       await client.delete(Uri.http(host, ''));
       final method = await httpServerQueue.next as String;