feat(fuzzing): fuzzing for felt addition

.gitignore

@@ -17,3 +17,7 @@ Cargo.lock
 # Added by cargo
 
 /target
+.DS_Store
+
+corpus/
+artifacts/

Cargo.toml

@@ -4,7 +4,7 @@ members = [
     "crates/starknet-types-rpc",
 ]
 
-exclude = ["ensure_no_std"]
+exclude = ["ensure_no_std", "fuzz"]
 resolver = "2"
 
 [workspace.package]

fuzz/Cargo.toml

@@ -0,0 +1,15 @@
+[workspace]
+members = ["felt"]
+
+resolver = "2"
+
+[workspace.package]
+authors = [
+    "Lucas Levy <@LucasLvy>",
+]
+edition = "2021"
+repository = "https://github.com/starknet-io/types-rs"
+
+[workspace.dependencies]
+starknet-types-core = { path = "../crates/starknet-types-core", default-features = false, features = ["arbitrary"] }
+libfuzzer-sys = "0.4"

fuzz/felt/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "fuzzing_felt"
+version = "0.0.1"
+edition = "2021"
+license = "MIT"
+homepage = "https://github.com/starknet-io/types-rs"
+repository = "https://github.com/starknet-io/types-rs"
+categories = ["types", "math", "crypto", "fuzzing"]
+keywords = ["stark", "zkp", "cairo", "fuzzing"]
+description = "Fuzzing crate for the starknet common felt type"
+readme = "README.md"
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+starknet-types-core.workspace = true
+libfuzzer-sys.workspace = true
+
+[[bin]]
+name = "add_fuzzer"
+path = "fuzz_targets/add.rs"
+test = false
+doc = false
+

fuzz/felt/fuzz_targets/add.rs

@@ -0,0 +1,22 @@
+#![no_main]
+use libfuzzer_sys::fuzz_target;
+use starknet_types_core::felt::Felt;
+
+fuzz_target!(|data: (Felt, Felt)| {
+    let zero = Felt::ZERO;
+    // Check a + 0 = a
+    assert_eq!(data.0 + zero, data.0, "Zero addition failed");
+    assert_eq!(data.1 + zero, data.1, "Zero addition failed");
+
+    // Check a + (-a) = 0
+    assert_eq!(data.0 + (-data.0), zero, "Unary addition failed");
+    assert_eq!(data.1 + (-data.1), zero, "Unary addition failed");
+
+    // Check a + b = a - (-b)
+    assert_eq!(data.0 + data.1, data.0 - (-data.1), "addition failed");
+    // Check a + a = a - (-a)
+    assert_eq!(data.0 + data.0, data.0 - (-data.0), "addition failed");
+    assert_eq!(data.1 + data.1, data.1 - (-data.1), "addition failed");
+    // Check a + a = 2 * a
+    assert_eq!(data.0 + data.0, Felt::TWO * data.0, "Doubling failed");
+});