Add Membership test (#500)

* Add membership type

* Update README.md

* Update README.md

* Resolve missing info

* Restore README

* Fix trailing line

* Fix range

* Fixed formatting

Co-authored-by: Trangar <gpg@trangar.com>

compatibility/src/lib.rs

@@ -3,6 +3,7 @@
 use ::rand::Rng;
 use bincode_1::Options;
 
+mod membership;
 mod misc;
 mod rand;
 mod sway;

compatibility/src/membership.rs

@@ -0,0 +1,52 @@
+// Added by [ppamorim](https://github.com/ppamorim)
+// Taken from https://github.com/datafuselabs/openraft/blob/209ae677ade5b624fea9f6630e9ff191963f5d74/openraft/src/membership/membership.rs#L21
+// License: Openraft is licensed under the terms of the MIT License or the Apache License 2.0, at your choosing.
+
+use rand::{prelude::ThreadRng, Rng};
+use std::collections::BTreeSet;
+
+type NodeId = u64;
+
+#[derive(
+    bincode_2::Encode, bincode_2::Decode, serde::Serialize, serde::Deserialize, Debug, PartialEq,
+)]
+#[bincode(crate = "bincode_2")]
+pub struct Membership {
+    /// learners set
+    learners: BTreeSet<NodeId>,
+
+    /// Multi configs.
+    configs: Vec<BTreeSet<NodeId>>,
+
+    /// Cache of all node ids.
+    all_members: BTreeSet<NodeId>,
+}
+
+#[test]
+pub fn test() {
+    let mut rng = rand::thread_rng();
+    for _ in 0..1000 {
+        crate::test_same(Membership {
+            learners: random_btreeset(&mut rng),
+            configs: vec_random_btreeset(&mut rng),
+            all_members: random_btreeset(&mut rng),
+        });
+    }
+}
+
+fn vec_random_btreeset(rng: &mut ThreadRng) -> Vec<BTreeSet<NodeId>> {
+    let mut vec = Vec::with_capacity(10);
+    for _ in 0..rng.gen_range(0..10) {
+        vec.push(random_btreeset(rng));
+    }
+    vec
+}
+
+fn random_btreeset(rng: &mut ThreadRng) -> BTreeSet<NodeId> {
+    let mut set = BTreeSet::new();
+    for _ in 0..rng.gen_range(0..100) {
+        let v = rng.gen();
+        set.insert(v);
+    }
+    set
+}