Add initial naive fuzz testing based on wasm-smith (#405)

* remove .idea from .gitignore

Developers should instead ignore .idea files locally.

* initial impl for Wasm parsing, validation and translation fuzz testing

This very simple implementation already found a bug in the wasmi_v1 Wasm -> wasmi bytecode translation procedure.

.gitignore

@@ -3,4 +3,7 @@
 **/*.rs.bk
 Cargo.lock
 spec/target
-.idea
+
+**/fuzz/corpus/
+**/fuzz/target/
+**/fuzz/artifacts/

wasmi_v1/fuzz/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "wasmi-fuzz"
+version = "0.0.0"
+authors = ["Parity Technologies <admin@parity.io>", "Robin Freyler <robin.freyler@gmail.com>"]
+publish = false
+edition = "2021"
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+libfuzzer-sys = "0.4"
+wasm-smith = "0.11"
+
+[dependencies.wasmi]
+path = ".."
+
+# Prevent this from interfering with workspaces
+[workspace]
+members = ["."]
+
+[[bin]]
+name = "translate"
+path = "fuzz_targets/translate.rs"
+test = false
+doc = false

wasmi_v1/fuzz/fuzz_targets/translate.rs

@@ -0,0 +1,9 @@
+#![no_main]
+use libfuzzer_sys::fuzz_target;
+use wasmi::{Engine, Module};
+
+fuzz_target!(|data: wasm_smith::Module| {
+    let wasm = data.to_bytes();
+    let engine = Engine::default();
+    Module::new(&engine, &mut &wasm[..]).unwrap();
+});