Runtime benchmarks: start (#136)

* runtime benchmarks: start

* merge tests + benchmarks infrastructure

* fix compilation

* Fix compilation issues with runtime-benchmark feature flag

Mainly involved pulling in correct dependencies and adding some functions
which were called but didn't yet exist.

* Fix broken compilation for tests

* Move header signing methods into trait

* Move signing related test helpers to own module

* Remove comment about feature flag

* Add constants to tests

* Add top level comment for testing utilities

Co-authored-by: Hernando Castano <castano.ha@gmail.com>

bridges/primitives/ethereum-poa/src/signatures.rs

@@ -0,0 +1,66 @@
+// Copyright 2020 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common 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.
+
+// Parity Bridges Common 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 Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+//
+
+//! Helpers related to signatures.
+//!
+//! Used for testing and benchmarking.
+
+use crate::{public_to_address, rlp_encode, step_validator, Address, Header, H256, H520};
+
+use secp256k1::{Message, PublicKey, SecretKey};
+
+/// Utilities for signing headers.
+pub trait SignHeader {
+	/// Signs header by given author.
+	fn sign_by(self, author: &SecretKey) -> Header;
+	/// Signs header by given authors set.
+	fn sign_by_set(self, authors: &[SecretKey]) -> Header;
+}
+
+impl SignHeader for Header {
+	fn sign_by(mut self, author: &SecretKey) -> Self {
+		self.author = secret_to_address(author);
+
+		let message = self.seal_hash(false).unwrap();
+		let signature = sign(author, message);
+		self.seal[1] = rlp_encode(&signature);
+		self
+	}
+
+	fn sign_by_set(self, authors: &[SecretKey]) -> Self {
+		let step = self.step().unwrap();
+		let author = step_validator(authors, step);
+		self.sign_by(author)
+	}
+}
+
+/// Return author's signature over given message.
+pub fn sign(author: &SecretKey, message: H256) -> H520 {
+	let (signature, recovery_id) = secp256k1::sign(&Message::parse(message.as_fixed_bytes()), author);
+	let mut raw_signature = [0u8; 65];
+	raw_signature[..64].copy_from_slice(&signature.serialize());
+	raw_signature[64] = recovery_id.serialize();
+	raw_signature.into()
+}
+
+/// Returns address corresponding to given secret key.
+pub fn secret_to_address(secret: &SecretKey) -> Address {
+	let public = PublicKey::from_secret_key(secret);
+	let mut raw_public = [0u8; 64];
+	raw_public.copy_from_slice(&public.serialize()[1..]);
+	public_to_address(&raw_public)
+}