feat: Add fuzzers for BTreeMap and MinHeap (#217)

- Added two fuzzers `stable_btreemap_multiple_ops_persistent` and
`stable_minheap_multiple_ops_persistent`
- Added a CI job to check if the fuzzers can be built. However, the
fuzzers are not run on CI yet.

To run a fuzzer locally, 
```sh
rustup toolchain install nightly
cargo install cargo-fuzz
cargo +nightly fuzz run stable_btreemap_multiple_ops_persistent
```

.github/workflows/ci.yml

@@ -28,6 +28,7 @@ jobs:
           rustup default ${{ matrix.rust }}
           rustup component add rustfmt
           rustup component add clippy
+          rustup toolchain install nightly
 
       - name: Check Format
         run: cargo fmt --all -- --check
@@ -39,6 +40,11 @@ jobs:
         run: cargo test
         env:
           RUST_BACKTRACE: 1
+
+      - name: Build Fuzzers
+        run: |
+          cargo install cargo-fuzz
+          cargo +nightly fuzz build
 
   examples:
     runs-on: ubuntu-latest

README.md

@@ -149,3 +149,19 @@ fn insert(key: u128, value: u128) -> Option<u128> {
 If your project exclusively relies on stable structures, the memory can expand in size without the requirement of `pre_upgrade`/`post_upgrade` hooks.
 
 However, it's important to note that if you also intend to perform serialization/deserialization of the heap data, utilizing the memory manager becomes necessary. To effectively combine both approaches, refer to the [Quickstart Example](https://github.com/dfinity/stable-structures/tree/main/examples/src/quick_start) for guidance.
+
+## Fuzzing
+
+Stable structures requires strong guarantees to work reliably and scale over millions of operations. To that extent, we use fuzzing to emulate such operations on the available data structures.
+
+To run a fuzzer locally, 
+```sh
+rustup toolchain install nightly
+cargo install cargo-fuzz
+
+# To list available fuzzer targets
+cargo +nightly fuzz list
+
+# To run a target 
+cargo +nightly fuzz run <TARGET_NAME>
+```

fuzz/.gitignore

@@ -0,0 +1,4 @@
+target
+corpus
+artifacts
+coverage

fuzz/Cargo.toml

@@ -0,0 +1,37 @@
+[package]
+name = "ic-stable-structures-fuzz"
+version = "0.0.0"
+publish = false
+edition = "2021"
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+libfuzzer-sys = "0.4"
+arbitrary = {version = "1.3.0", features = ["derive"]}
+serde = {version = "1.0", features = ["derive"]}
+serde_bytes = "0.11"
+serde_cbor = "0.11.2"
+tempfile = "3.3.0"
+
+[dependencies.ic-stable-structures]
+path = ".."
+
+# Prevent this from interfering with workspaces
+[workspace]
+members = ["."]
+
+[[bin]]
+name = "stable_btreemap_multiple_ops_persistent"
+path = "fuzz_targets/stable_btreemap_multiple_ops_persistent.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "stable_minheap_multiple_ops_persistent"
+path = "fuzz_targets/stable_minheap_multiple_ops_persistent.rs"
+test = false
+doc = false
+bench = false