Write a fuzz test

eth2/utils/ssz/fuzz/Cargo.toml

@@ -18,5 +18,5 @@ git = "https://github.com/rust-fuzz/libfuzzer-sys.git"
 members = ["."]
 
 [[bin]]
-name = "fuzz_target_1"
-path = "fuzz_targets/fuzz_target_1.rs"
+name = "fuzz_target_u8"
+path = "fuzz_targets/fuzz_target_u8.rs"

eth2/utils/ssz/fuzz/fuzz_targets/fuzz_target_1.rs

@@ -1,7 +0,0 @@
-#![no_main]
-#[macro_use] extern crate libfuzzer_sys;
-extern crate ssz;
-
-fuzz_target!(|data: &[u8]| {
-    // fuzzed code goes here
-});

eth2/utils/ssz/fuzz/fuzz_targets/fuzz_target_u8.rs

@@ -0,0 +1,10 @@
+#![no_main]
+#[macro_use] extern crate libfuzzer_sys;
+extern crate ssz;
+
+use ssz::{DecodeError, Decodable, Encodable};
+
+// Fuzz ssz_decode(u8)
+fuzz_target!(|data: &[u8]| {
+    let result: Result<(u8, usize), DecodeError> = Decodable::ssz_decode(data, 0);
+});