Custom RPC implementation for node. (#3109)

* Allow RPCs to be customized.

* Implement node-rpc extensions.

* Working on a test.

* Add node-testing crate.

* Fix genesis test config

* Fix nonce lookups.

* Clean up.

* Fix expected block type.

* Make the RPC extension function optional.

* Fix service doc test.

* Bump jsonrpc.

* Bump client version.

* Update Cargo.lock

* Update jsonrpc.

* Fix build.

* Remove unused imports.

* Fix signed extra.

* Post merge clean up.

* Fix tests.

* Patch hashmap-core.

* Fix build.

* Fix build.

* Remove hashmap_core patches.

substrate/node/testing/src/client.rs

@@ -0,0 +1,73 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate 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.
+
+// Substrate 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 Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Utilites to build a `TestClient` for `node-runtime`.
+
+use sr_primitives::BuildStorage;
+
+/// Re-export test-client utilities.
+pub use test_client::*;
+
+/// Call executor for `node-runtime` `TestClient`.
+pub type Executor = substrate_executor::NativeExecutor<node_executor::Executor>;
+
+/// Default backend type.
+pub type Backend = client_db::Backend<node_primitives::Block>;
+
+/// Test client type.
+pub type Client = client::Client<
+	Backend,
+	client::LocalCallExecutor<Backend, Executor>,
+	node_primitives::Block,
+	node_runtime::RuntimeApi,
+>;
+
+/// Genesis configuration parameters for `TestClient`.
+#[derive(Default)]
+pub struct GenesisParameters {
+	support_changes_trie: bool,
+}
+
+impl test_client::GenesisInit for GenesisParameters {
+	fn genesis_storage(&self) -> (StorageOverlay, ChildrenStorageOverlay) {
+		crate::genesis::config(self.support_changes_trie, None).build_storage().unwrap()
+	}
+}
+
+/// A `test-runtime` extensions to `TestClientBuilder`.
+pub trait TestClientBuilderExt: Sized {
+	/// Create test client builder.
+	fn new() -> Self;
+
+	/// Build the test client.
+	fn build(self) -> Client;
+}
+
+impl TestClientBuilderExt for test_client::TestClientBuilder<
+	client::LocalCallExecutor<Backend, Executor>,
+	Backend,
+	GenesisParameters,
+> {
+	fn new() -> Self{
+		Self::default()
+	}
+
+	fn build(self) -> Client {
+		self.build_with_native_executor(None).0
+	}
+}
+
+