[InclusiveRange]: Allow size one ranges

Removed the check that denied InclusiveRanges where start was
equal with end.
Added a test to check that allocation succeds when there is a size 1
range before or after the requested range.

Signed-off-by: AlexandruCihodaru <[email protected]>

src/address_allocator.rs

@@ -244,6 +244,19 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_allow_range_size_one_left() {
+        let mut pool = AddressAllocator::new(1, 1000).unwrap();
+        assert_eq!(
+            pool.allocate(10, 2, AllocPolicy::FirstMatch).unwrap(),
+            RangeInclusive::new(2, 11).unwrap()
+        );
+        assert_eq!(
+            pool.allocate(1, 1, AllocPolicy::FirstMatch).unwrap(),
+            RangeInclusive::new(1, 1).unwrap()
+        );
+    }
+
     #[test]
     fn test_allocate_address_fail_free_and_realloc() {
         let mut pool = AddressAllocator::new(0x0, 0x1000).unwrap();

src/lib.rs

@@ -171,7 +171,7 @@ impl RangeInclusive {
         // The length of the interval [0, u64::MAX] is u64::MAX + 1 which does
         // not fit in a u64::MAX, hence we return `Error::InvalidRange` when
         // there is an attempt to use that range.
-        if start >= end || (start == 0 && end == u64::MAX) {
+        if start > end || (start == 0 && end == u64::MAX) {
             return Err(Error::InvalidRange(start, end));
         }
         Ok(RangeInclusive { start, end })
@@ -311,8 +311,8 @@ mod tests {
             Error::InvalidRange(2, 1)
         );
         assert_eq!(
-            RangeInclusive::new(1, 1).unwrap_err(),
-            Error::InvalidRange(1, 1)
+            RangeInclusive::new(0, u64::MAX).unwrap_err(),
+            Error::InvalidRange(0, u64::MAX)
         );
     }