Improve and unify testing facilities (#1844)

* Improve and unify testing facilities

This improves the testing facilities by making the test client easier to
use. It also removes code that is not required for the test client.
Besides that it also moves the test service and test client under
`node/test`.

* Update Cargo.lock

* Update node/test/client/src/block_builder.rs

Co-authored-by: Andronik Ordian <write@reusable.software>

* Remove explicit lifetime annotation

* Fix warnings and add extra `BlockBuilderExt`

Co-authored-by: Andronik Ordian <write@reusable.software>

polkadot/node/test/service/tests/call-function.rs

@@ -0,0 +1,44 @@
+// Copyright 2020 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use polkadot_test_service::*;
+use service::TaskExecutor;
+use sp_keyring::Sr25519Keyring::{Alice, Bob};
+
+#[substrate_test_utils::test]
+async fn call_function_actually_work(task_executor: TaskExecutor) {
+	let alice = run_test_node(task_executor, Alice, || {}, Vec::new());
+
+	let function = polkadot_test_runtime::Call::Balances(pallet_balances::Call::transfer(
+		Default::default(),
+		1,
+	));
+	let output = alice.send_extrinsic(function, Bob).await.unwrap();
+
+	let res = output.result.expect("return value expected");
+	let json = serde_json::from_str::<serde_json::Value>(res.as_str()).expect("valid JSON");
+	let object = json.as_object().expect("JSON is an object");
+	assert!(object.contains_key("jsonrpc"), "key jsonrpc exists");
+	let result = object.get("result");
+	let result = result.expect("key result exists");
+	assert_eq!(
+		result.as_str().map(|x| x.starts_with("0x")),
+		Some(true),
+		"result starts with 0x"
+	);
+
+	alice.task_manager.clean_shutdown().await;
+}