RUST-672 Handle reserved values for BinarySubtype (#269)

* RUST-672 Handle reserved values for BinarySubtype

* use test lock

Author: abr-egn

src/spec.rs

@@ -53,6 +53,7 @@ const BINARY_SUBTYPE_UUID_OLD: u8 = 0x03;
 const BINARY_SUBTYPE_UUID: u8 = 0x04;
 const BINARY_SUBTYPE_MD5: u8 = 0x05;
 const BINARY_SUBTYPE_ENCRYPTED: u8 = 0x06;
+const BINARY_SUBTYPE_USER_DEFINED: u8 = 0x80;
 
 /// All available BSON element types.
 ///
@@ -151,6 +152,7 @@ pub enum BinarySubtype {
     Md5,
     Encrypted,
     UserDefined(u8),
+    Reserved(u8),
 }
 
 impl From<BinarySubtype> for u8 {
@@ -165,6 +167,7 @@ impl From<BinarySubtype> for u8 {
             BinarySubtype::Md5 => BINARY_SUBTYPE_MD5,
             BinarySubtype::Encrypted => BINARY_SUBTYPE_ENCRYPTED,
             BinarySubtype::UserDefined(x) => x,
+            BinarySubtype::Reserved(x) => x,
         }
     }
 }
@@ -180,6 +183,7 @@ impl From<u8> for BinarySubtype {
             BINARY_SUBTYPE_UUID => BinarySubtype::Uuid,
             BINARY_SUBTYPE_MD5 => BinarySubtype::Md5,
             BINARY_SUBTYPE_ENCRYPTED => BinarySubtype::Encrypted,
+            _ if t < BINARY_SUBTYPE_USER_DEFINED => BinarySubtype::Reserved(t),
             _ => BinarySubtype::UserDefined(t),
         }
     }

src/tests/binary_subtype.rs

@@ -0,0 +1,13 @@
+use crate::{spec::BinarySubtype, tests::LOCK};
+
+#[test]
+fn from_u8() {
+    let _guard = LOCK.run_concurrently();
+    // Check the endpoints of the defined, reserved, and user-defined subtype ranges.
+    assert_eq!(BinarySubtype::from(0x00), BinarySubtype::Generic);
+    assert_eq!(BinarySubtype::from(0x06), BinarySubtype::Encrypted);
+    assert_eq!(BinarySubtype::from(0x07), BinarySubtype::Reserved(0x07));
+    assert_eq!(BinarySubtype::from(0x7F), BinarySubtype::Reserved(0x7F));
+    assert_eq!(BinarySubtype::from(0x80), BinarySubtype::UserDefined(0x80));
+    assert_eq!(BinarySubtype::from(0xFF), BinarySubtype::UserDefined(0xFF));
+}

src/tests/mod.rs

@@ -1,3 +1,4 @@
+mod binary_subtype;
 mod modules;
 mod serde;
 mod spec;