removed redundant method and improved assertions of the original

src/vec.rs

@@ -22,13 +22,6 @@ impl<T, A: Allocator> Vec<T, A> {
         self.inner.allocator()
     }
 
-    #[inline]
-    pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result<Self, TryReserveError> {
-        Ok(Self {
-            inner: InnerVec::try_with_capacity_in(capacity, alloc)?,
-        })
-    }
-
     #[inline]
     pub fn capacity(&self) -> usize {
         self.inner.capacity()
@@ -41,9 +34,9 @@ impl<T, A: Allocator> Vec<T, A> {
 
     #[inline]
     pub fn with_capacity_in(capacity: usize, alloc: A) -> Result<Self, TryReserveError> {
-        let mut vec = Self::new_in(alloc);
-        vec.reserve(capacity)?;
-        Ok(vec)
+        Ok(Self {
+            inner: InnerVec::try_with_capacity_in(capacity, alloc)?,
+        })
     }
 
     #[inline]
@@ -378,7 +371,10 @@ mod tests {
     fn test_with_capacity_in() {
         let wma = WatermarkAllocator::new(32);
         let vec: Vec<usize, _> = Vec::with_capacity_in(4, wma.clone()).unwrap();
+        assert_eq!(vec.len(), 0);
+        assert_eq!(vec.as_slice(), &[]);
         assert_eq!(vec.inner.capacity(), 4);
+        assert_eq!(wma.in_use(), 4 * size_of::<usize>());
 
         let _err: TryReserveError = Vec::<i8, _>::with_capacity_in(5, wma).unwrap_err();
     }
@@ -613,16 +609,6 @@ mod tests {
         assert_eq!(wma.in_use(), 0);
     }
 
-    #[test]
-    fn try_with_capacity_in() {
-        let wma = WatermarkAllocator::new(64);
-        let vec: Vec<u8, _> = Vec::try_with_capacity_in(64, wma.clone()).unwrap();
-        assert_eq!(vec.len(), 0);
-        assert_eq!(vec.as_slice(), &[]);
-        assert_eq!(vec.capacity(), 64);
-        assert_eq!(wma.in_use(), 64);
-    }
-
     #[test]
     fn test_truncate() {
         let wma = WatermarkAllocator::new(32);