Contracts move fixtures to new crate (#2246)

Small PR that introduce a new crate that will host RISC-V & wasm
fixtures for testing pallet-contracts

substrate/frame/contracts/fixtures/src/lib.rs

@@ -0,0 +1,42 @@
+// This file is part of Substrate.
+
+// Copyright (C) Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use sp_runtime::traits::Hash;
+use std::{env::var, path::PathBuf};
+
+fn fixtures_root_dir() -> PathBuf {
+	match (var("CARGO_MANIFEST_DIR"), var("CARGO_PKG_NAME")) {
+		// When `CARGO_MANIFEST_DIR` is not set, Rust resolves relative paths from the root folder
+		(Err(_), _) => "substrate/frame/contracts/fixtures/data".into(),
+		(Ok(path), Ok(s)) if s == "pallet-contracts" => PathBuf::from(path).join("fixtures/data"),
+		(Ok(_), pkg_name) => panic!("Failed to resolve fixture dir for tests from {pkg_name:?}."),
+	}
+}
+
+/// Load a given wasm module represented by a .wat file and returns a wasm binary contents along
+/// with it's hash.
+///
+/// The fixture files are located under the `fixtures/` directory.
+pub fn compile_module<T>(fixture_name: &str) -> wat::Result<(Vec<u8>, <T::Hashing as Hash>::Output)>
+where
+	T: frame_system::Config,
+{
+	let fixture_path = fixtures_root_dir().join(format!("{fixture_name}.wat"));
+	let wasm_binary = wat::parse_file(fixture_path)?;
+	let code_hash = T::Hashing::hash(&wasm_binary);
+	Ok((wasm_binary, code_hash))
+}