add test for disconnect method

Author: AlaaElattar

packages/tfchain_client/lib/src/client.dart

@@ -74,7 +74,9 @@ class QueryClient {
   }
 
   Future<void> disconnect() async {
-    await api.disconnect();
+    if (provider!.isConnected()) {
+      await api.disconnect();
+    }
   }
 }
 

packages/tfchain_client/test/client_test.dart

@@ -42,7 +42,10 @@ void main() {
       expect(queryClient.api, isNotNull);
     });
 
-    // TODO: How to test disconnect ??
+    test('Disconnect', () async {
+      await queryClient.disconnect();
+      expect(false, queryClient.provider!.isConnected());
+    });
   });
 
   group("Full Client Tests", () {
@@ -78,5 +81,10 @@ void main() {
       expect(client.provider, isA<WsProvider>());
       expect(client.api, isNotNull);
     });
+
+    test('Disconnect', () async {
+      await client.disconnect();
+      expect(false, client.provider!.isConnected());
+    });
   });
 }

packages/tfchain_client/test/contracts_test.dart

@@ -134,16 +134,16 @@ void main() {
     });
 
     // TODO: 
-    // test('Test Create Name Contract then cancel it', () async {
-    //   BigInt? contractId = await client.contracts.createName(name: "xxx");
-    //   expect(contractId, isNotNull);
-    //   await Future.delayed(Duration(seconds: 5));
-    //   try {
-    //     await client.contracts.cancel(contractId: contractId!);
-    //   } catch (error) {
-    //     expect(error, isNull);
-    //   }
-    // });
+    test('Test Create Name Contract then cancel it', () async {
+      BigInt? contractId = await client.contracts.createName(name: "xxx");
+      expect(contractId, isNotNull);
+      await Future.delayed(Duration(seconds: 5));
+      try {
+        await client.contracts.cancel(contractId: contractId!);
+      } catch (error) {
+        expect(error, isNull);
+      }
+    });
 
     test('Test Create Rent Contract with no solution provider', () async {
       try {