Fix negative numbers order

Author: hansl

ciborium/src/value/integer.rs

@@ -85,6 +85,15 @@ impl Integer {
                     (true, false) => {
                         Ordering::Greater
                     }
+                    (true, true) => {
+                        // For negative numbers the byte order puts numbers closer to 0 which
+                        // are lexically higher, lower. So -1 < -2 when sorting by be_bytes().
+                        match self.0.cmp(&other.0) {
+                            Ordering::Less => Ordering::Greater,
+                            Ordering::Equal => Ordering::Equal,
+                            Ordering::Greater => Ordering::Less,
+                        }
+                    }
                     (_, _) => {
                         self.0.cmp(&other.0)
                     }

ciborium/tests/canonical.rs

@@ -58,3 +58,31 @@ fn map() {
 
     assert_eq!(hex::encode(&bytes1), "a80a002001f402186403617a048120056261610681186407");
 }
+
+#[test]
+fn negative_numbers() {
+    let mut array: Vec<CanonicalValue> = vec![
+        cval!(10),
+        cval!(-1),
+        cval!(-2),
+        cval!(-3),
+        cval!(-4),
+        cval!(false),
+        cval!(100),
+        cval!(-100),
+        cval!(-200),
+        cval!("z"),
+        cval!([-1]),
+        cval!(-300),
+        cval!("aa"),
+        cval!([100]),
+    ];
+    let golden = array.clone();
+
+    // Shuffle the array.
+    array.shuffle(&mut rand::thread_rng());
+
+    array.sort();
+
+    assert_eq!(array, golden);
+}