Add simple client test

Author: simolus3

pubspec.yaml

@@ -28,6 +28,7 @@ dependencies:
   collection: ^1.14.11
 
 dev_dependencies:
+  async: ^2.8.2
   build_runner: ^2.0.3
   build_test: ^2.1.0
   web_socket_channel: ^2.0.0

test/core/client_test.dart

@@ -0,0 +1,17 @@
+import 'package:test/test.dart';
+import 'package:web3dart/web3dart.dart';
+
+import '../mock_client.dart';
+
+void main() {
+  test('getClientVersion', () async {
+    final client = MockClient(expectAsync2((method, data) {
+      expect(method, 'web3_clientVersion');
+      return 'dart-web3dart-test';
+    }));
+    final web3 = Web3Client('', client);
+    addTearDown(web3.dispose);
+
+    expect(web3.getClientVersion(), completion('dart-web3dart-test'));
+  });
+}

test/mock_client.dart

@@ -0,0 +1,50 @@
+import 'dart:convert';
+
+import 'package:async/async.dart';
+import 'package:http/http.dart';
+import 'package:test/test.dart';
+
+class MockClient extends BaseClient {
+  static final _jsonUtf8 = json.fuse(utf8);
+
+  final Object? Function(String method, Object? payload) handler;
+
+  MockClient(this.handler);
+
+  @override
+  Future<StreamedResponse> send(BaseRequest request) async {
+    final data = await _jsonUtf8.decoder.bind(request.finalize()).first;
+
+    if (data is! Map) {
+      fail('Invalid request, expected JSON map');
+    }
+
+    if (data['jsonrpc'] != '2.0') {
+      fail('Expected request to contain correct jsonrpc key');
+    }
+
+    final id = data['id'];
+    final method = data['method'] as String;
+    final params = data['params'];
+
+    final response = Result(() => handler(method, params));
+
+    return StreamedResponse(
+      _jsonUtf8.encoder.bind(
+        Stream.value(
+          {
+            'jsonrpc': '2.0',
+            if (response is ValueResult) 'result': response.value,
+            if (response is ErrorResult)
+              'error': {
+                'code': -1,
+                'message': '${response.error}',
+              },
+            'id': id,
+          },
+        ),
+      ),
+      200,
+    );
+  }
+}