RUST-2266 Add HashSet to Bson conversion (#598)

Co-authored-by: Abraham Egnor <abraham.egnor@mongodb.com>

Author: TheDan64

src/bson.rs

@@ -22,6 +22,7 @@
 //! BSON definition
 
 use std::{
+    collections::HashSet,
     convert::TryFrom,
     fmt::{self, Debug, Display, Formatter},
     hash::Hash,
@@ -342,6 +343,12 @@ where
     }
 }
 
+impl<T: Into<Bson>, S> From<HashSet<T, S>> for Bson {
+    fn from(s: HashSet<T, S>) -> Bson {
+        Bson::from_iter(s)
+    }
+}
+
 impl<T> From<&[T]> for Bson
 where
     T: Clone + Into<Bson>,

src/tests/modules/bson.rs

@@ -1,4 +1,5 @@
 use std::{
+    collections::HashSet,
     convert::TryFrom,
     time::{Duration, SystemTime},
 };
@@ -558,3 +559,44 @@ fn test_hashable() {
 
     assert!(map.is_empty());
 }
+
+#[test]
+fn test_hash_set_to_bson() {
+    let mut set1 = HashSet::new();
+    let mut set2 = HashSet::new();
+
+    set1.insert(1);
+    set1.insert(2);
+    set1.insert(3);
+    set2.insert(&1);
+    set2.insert(&2);
+    set2.insert(&3);
+
+    let d1 = doc! {
+        "foo": set1,
+    };
+    let d2 = doc! {
+        "foo": set2,
+    };
+    let a1: Vec<_> = d1
+        .get_array("foo")
+        .unwrap()
+        .iter()
+        .map(|v| v.as_i32().unwrap())
+        .collect();
+    let a2: Vec<_> = d2
+        .get_array("foo")
+        .unwrap()
+        .iter()
+        .map(|v| v.as_i32().unwrap())
+        .collect();
+
+    assert_eq!(a1.len(), 3);
+    assert_eq!(a2.len(), 3);
+    assert!(a1.contains(&1));
+    assert!(a1.contains(&2));
+    assert!(a1.contains(&3));
+    assert!(a2.contains(&1));
+    assert!(a2.contains(&2));
+    assert!(a2.contains(&3));
+}