From a3fc564dc3b1faf776a77cd2da717ee9360ddee5 Mon Sep 17 00:00:00 2001
From: Aurelien Clu <aurelien-clu@users.noreply.github.com>
Date: Thu, 4 Jan 2024 22:53:37 +0900
Subject: [PATCH] Implement std::hash::Hash for Ksuid structs. (#7)

Co-authored-by: Aurelien Somename <aurelien.somename@gmail.com>
---
 src/lib.rs           | 13 +++++++++++
 tests/integration.rs | 54 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index b91d3a3..635ad9b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -60,6 +60,7 @@
 //! All rights reserved to the [Svix webhooks service](https://www.svix.com).
 
 use core::fmt;
+use std::hash::{Hash, Hasher};
 use std::{error, str::FromStr};
 
 use byteorder::{BigEndian, ByteOrder};
@@ -355,6 +356,12 @@ impl fmt::Display for Ksuid {
     }
 }
 
+impl Hash for Ksuid {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.0.hash(state);
+    }
+}
+
 /// K-Sortable Unique ID (Ms accuracy)
 ///
 /// This one has Ms accuracy compared to the normal one that has second accuracy
@@ -493,6 +500,12 @@ impl fmt::Display for KsuidMs {
     }
 }
 
+impl Hash for KsuidMs {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.0.hash(state);
+    }
+}
+
 #[cfg(feature = "serde")]
 impl Serialize for Ksuid {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
diff --git a/tests/integration.rs b/tests/integration.rs
index e962c0f..a109a9a 100644
--- a/tests/integration.rs
+++ b/tests/integration.rs
@@ -1,6 +1,8 @@
 use serde::Deserialize;
 #[cfg(feature = "serde")]
 use serde::Serialize;
+use std::collections::HashSet;
+use std::hash::{Hash, Hasher};
 use std::{
     fs::File,
     io::{self, BufRead},
@@ -103,6 +105,58 @@ fn test_ordering() -> Result<(), String> {
     Ok(())
 }
 
+#[test]
+fn test_hash() {
+    // given
+    let mut set = HashSet::new();
+    let ksuid1 = Ksuid::new(None, None);
+    let ksuid2 = Ksuid::new(None, None);
+    // when
+    set.insert(ksuid1.clone());
+    set.insert(ksuid2.clone());
+    // then
+    assert_eq!(set.len(), 2);
+    assert!(set.contains(&ksuid1));
+    assert!(set.contains(&ksuid2));
+}
+
+#[test]
+fn test_hash_ms() {
+    // given
+    let mut set = HashSet::new();
+    let ksuidms1 = KsuidMs::new(None, None);
+    let ksuidms2 = KsuidMs::new(None, None);
+    // when
+    set.insert(ksuidms1.clone());
+    set.insert(ksuidms2.clone());
+    // then
+    assert_eq!(set.len(), 2);
+    assert!(set.contains(&ksuidms1));
+    assert!(set.contains(&ksuidms2));
+}
+
+#[test]
+fn test_hash_are_deterministic() {
+    let cases: Vec<(&str, u64)> = vec![
+        ("000000pryYUMiBILyxOCoroLz6w", 7055508431330265589),
+        ("02GY99XXwBHbeBundUPJoqYpvet", 3000553476947541532),
+        ("04X6IIDacKaayM4WWom0flpf3mY", 15766199744355542564),
+    ];
+
+    for case in cases {
+        // given
+        let id_as_str = case.0;
+        let expected_hash = case.1;
+        // when
+        let ksuid = Ksuid::from_str(id_as_str).expect("valid id");
+        let mut hasher = std::collections::hash_map::DefaultHasher::new();
+        ksuid.hash(&mut hasher);
+        let hashed = hasher.finish();
+        // then
+        assert_eq!(hashed, expected_hash);
+    }
+}
+
 #[cfg(feature = "serde")]
 #[derive(Serialize, Deserialize)]
 struct TestKsuid {