Add RegKey::rename_subkey() method

Fixes #58

src/reg_key.rs

@@ -317,6 +317,34 @@ impl RegKey {
         }
     }
 
+    /// Rename a subkey
+    ///
+    /// # Examples
+    /// ```no_run
+    /// # use std::error::Error;
+    /// # use winreg::RegKey;
+    /// # use winreg::enums::*;
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// let items = RegKey::predef(HKEY_CURRENT_USER).open_subkey(r"Software\MyProduct\Items")?;
+    /// items.rename_subkey("itemA", "itemB")?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn rename_subkey<ON: AsRef<OsStr>, NN: AsRef<OsStr>>(
+        &self,
+        old_name: ON,
+        new_name: NN,
+    ) -> io::Result<()> {
+        let c_old_name = to_utf16(old_name);
+        let c_new_name = to_utf16(new_name);
+        match unsafe {
+            winapi_reg::RegRenameKey(self.hkey, c_old_name.as_ptr(), c_new_name.as_ptr())
+        } {
+            0 => Ok(()),
+            err => werr!(err),
+        }
+    }
+
     /// Copy all the values and subkeys from `path` to `dest` key.
     /// Will copy the content of `self` if `path` is an empty string.
     ///

tests/reg_key.rs

@@ -98,6 +98,17 @@ fn test_delete_subkey_with_flags() {
         .is_ok());
 }
 
+#[test]
+fn test_rename_subkey() {
+    with_key!(key, "RenameSubkey" => {
+        let old_name = "SubkeyA";
+        let new_name = "SubkeyB";
+        key.create_subkey(old_name).unwrap();
+        assert!(key.rename_subkey(old_name, new_name).is_ok());
+        assert!(key.open_subkey(new_name).is_ok());
+    });
+}
+
 #[test]
 fn test_copy_tree() {
     with_key!(key, "CopyTree" => {