Merge pull request #14 from Sajjon/fix_bug_dont_delete_element_if-try_update_with_fails

Fix bug, dont delete element of try_update_with fails.

Author: Sajjon

src/vec/identified_vec.rs

@@ -490,16 +490,22 @@ where
     #[inline]
     fn try_update_with<F, Er>(&mut self, id: &I, mut mutate: F) -> Result<bool, Er>
     where
-        F: FnMut(E) -> Result<E, Er>,
+        F: FnMut(&mut E) -> Result<E, Er>,
     {
         if !self.contains_id(id) {
             return Ok(false);
         }
         let mut existing = self.elements.remove(id).expect("Element for existing id");
-        mutate(existing).map(|updated| {
-            self.elements.insert(id.clone(), updated);
-            true
-        })
+
+        mutate(&mut existing)
+            .map(|updated| {
+                self.elements.insert(id.clone(), updated);
+                true
+            })
+            .map_err(|e| {
+                self.elements.insert(id.clone(), existing);
+                e
+            })
     }
 
     /// Try to update the given element to the `identified_vec` if a element with the same ID is already present.

src/vec/is_identified_vec.rs

@@ -147,7 +147,7 @@ where
 
     fn try_update_with<F, Er>(&mut self, id: &ID, mutate: F) -> Result<bool, Er>
     where
-        F: FnMut(Element) -> Result<Element, Er>;
+        F: FnMut(&mut Element) -> Result<Element, Er>;
 
     /// Insert a new member to this identified_vec at the specified index, if the identified_vec doesn't already contain
     /// it.

src/vec_of/is_identified_vec_of_via.rs

@@ -186,7 +186,7 @@ where
         mut mutate: F,
     ) -> Result<bool, Er>
     where
-        F: FnMut(Element) -> Result<Element, Er>,
+        F: FnMut(&mut Element) -> Result<Element, Er>,
     {
         self.via_mut().try_update_with(id, mutate)
     }

tests/tests.rs

@@ -410,9 +410,8 @@ fn try_update_with_contains() {
     sut.append(User::new(2, "Blob, Jr."));
     assert_eq!(
         sut.try_update_with(&2, |x| {
-            let mut y = x;
-            *y.name.get_mut() = "Junior, Jr.".to_string();
-            Result::<User, ()>::Ok(y)
+            *x.name.get_mut() = "Junior, Jr.".to_string();
+            Result::<User, ()>::Ok(x.clone())
         }),
         Ok(true)
     );
@@ -425,15 +424,43 @@ fn try_update_with_not_contains() {
     sut.append(User::new(2, "Blob, Jr."));
     assert_eq!(
         sut.try_update_with(&999, |x| {
-            let mut y = x;
-            *y.name.get_mut() = "Will never happen.".to_string();
-            Result::<User, ()>::Ok(y)
+            *x.name.get_mut() = "Will never happen.".to_string();
+            Result::<User, ()>::Ok(x.clone())
         }),
         Ok(false)
     );
     assert_eq!(sut.items(), [User::new(2, "Blob, Jr.")]);
 }
 
+#[test]
+fn try_update_with_failure_does_not_delete_element() {
+    let mut sut = Users::new();
+    sut.append(User::new(1, "Blob."));
+    sut.append(User::new(2, "Blob, Jr."));
+    sut.append(User::new(3, "Blob, Sr."));
+
+    assert_eq!(
+        sut.items(),
+        [
+            User::new(1, "Blob."),
+            User::new(2, "Blob, Jr."),
+            User::new(3, "Blob, Sr.")
+        ]
+    );
+
+    assert_eq!(sut.try_update_with(&2, |_| { Err(false) }), Err(false));
+
+    // remains unchanged
+    assert_eq!(
+        sut.items(),
+        [
+            User::new(1, "Blob."),
+            User::new(2, "Blob, Jr."),
+            User::new(3, "Blob, Sr.")
+        ]
+    );
+}
+
 #[test]
 #[should_panic(expected = "Expected element at index {index}")]
 fn update_at_expect_panic_unknown_index() {