add fuzzer

Author: Dr-Emann

fuzz/.gitignore

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

fuzz/Cargo.lock

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+[package]
+name = "roaring-fuzz"
+version = "0.0.0"
+publish = false
+edition = "2021"
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+libfuzzer-sys = { version = "0.4.9", features = ["arbitrary-derive"] }
+roaring = { path = "../roaring" }
+croaring = "2.0"
+
+[[bin]]
+name = "against_croaring"
+path = "fuzz_targets/against_croaring.rs"
+test = false
+doc = false
+bench = false
+
+[workspace]

fuzz/Cargo.toml

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+#![no_main]
+
+mod arbitrary_ops;
+
+use libfuzzer_sys::arbitrary::{self, Arbitrary};
+use libfuzzer_sys::fuzz_target;
+
+use crate::arbitrary_ops::{check_equal, Operation};
+
+#[derive(Arbitrary, Debug)]
+struct FuzzInput<'a> {
+    ops: Vec<Operation>,
+    initial_input: &'a [u8],
+}
+
+fuzz_target!(|input: FuzzInput| {
+    let lhs_c = croaring::Bitmap::try_deserialize::<croaring::Portable>(input.initial_input);
+    let lhs_r = roaring::RoaringBitmap::deserialize_from(input.initial_input).ok();
+
+    let (mut lhs_c, mut lhs_r) = match (lhs_c, lhs_r) {
+        (Some(lhs_c), Some(lhs_r)) => {
+            check_equal(&lhs_c, &lhs_r);
+            (lhs_c, lhs_r)
+        }
+        (None, None) => Default::default(),
+        (Some(_), None) => panic!("croaring deserialized, but roaring failed"),
+        (None, Some(_)) => panic!("roaring deserialized, but croaring failed"),
+    };
+
+    let mut rhs_c = croaring::Bitmap::new();
+    let mut rhs_r = roaring::RoaringBitmap::new();
+
+    for op in input.ops {
+        op.apply(&mut lhs_c, &mut rhs_c, &mut lhs_r, &mut rhs_r);
+    }
+    check_equal(&lhs_c, &lhs_r);
+    check_equal(&rhs_c, &rhs_r);
+});