✅ test: When there is no diff, do not patch

joebobmiles · Jul 13, 2021 · 0e3ecb1 · 0e3ecb1
1 parent 9ab35a5
commit 0e3ecb1
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Showing 2 changed files with 59 additions and 57 deletions.
diff --git a/src/patching.spec.ts b/src/patching.spec.ts
@@ -652,28 +652,24 @@ describe("patchStore", () =>
     expect(store.getState())
       .toEqual({ "owner": { "person": { "age": 1, "name": "Joe", }, }, });
   });
-});
 
-describe("Combining patchSharedType and patchStore.", () =>
-{
-  it("Does not clobber state when updating shared type.", () =>
+  it("Does not truncate state if there are no changes.", () =>
   {
-    const ydoc = new Y.Doc();
-    const ymap = ydoc.getMap("map");
-
-    ymap.observeDeep(() =>
+    type State =
     {
-      patchStore(api, ymap.toJSON());
-    });
+      "count": 0,
+    };
 
-    const api = create(() =>
+    const store = create<State>(() =>
       ({
-        "count": 1,
+        "count": 0,
       }));
 
-    patchSharedType(ymap, api.getState());
+    patchStore(
+      store,
+      { "count": 0, }
+    );
 
-    expect(api.getState().count).toBe(1);
-    expect(ymap.get("count")).toBe(1);
+    expect(store.getState()).toEqual({ "count": 0, });
   });
 });
diff --git a/src/patching.ts b/src/patching.ts
@@ -177,52 +177,58 @@ export const patchStore = <S extends State>(
   {
     const changes = getChangeList(oldState, newState);
 
-    const p: any = changes.reduce(
-      (state, [ type, property, value ]) =>
-      {
-        switch (type)
-        {
-        case "add":
-        case "update":
-        case "none":
-        {
-          return {
-            ...state,
-            [property]: value,
-          };
-        }
+    if (changes.length === 0)
+      return oldState;
 
-        case "pending":
+    else
+    {
+      const p: any = changes.reduce(
+        (state, [ type, property, value ]) =>
         {
-          return {
-            ...state,
-            [property]: patch(
-              oldState[property as string],
-              newState[property as string]
-            ),
-          };
-        }
+          switch (type)
+          {
+          case "add":
+          case "update":
+          case "none":
+          {
+            return {
+              ...state,
+              [property]: value,
+            };
+          }
 
-        case "delete":
-        default:
-          return state;
-        }
-      },
-      {}
-    );
-
-    return {
-      ...Object.entries(oldState).reduce(
-        (o, [ property, value ]) =>
-          (
-            value instanceof Function
-              ? { ...o, [property]: value, }
-              : o
-          ),
+          case "pending":
+          {
+            return {
+              ...state,
+              [property]: patch(
+                oldState[property as string],
+                newState[property as string]
+              ),
+            };
+          }
+
+          case "delete":
+          default:
+            return state;
+          }
+        },
         {}
-      ),
-      ...p,
-    };
+      );
+
+      return {
+        ...Object.entries(oldState).reduce(
+          (o, [ property, value ]) =>
+            (
+              value instanceof Function
+                ? { ...o, [property]: value, }
+                : o
+            ),
+          {}
+        ),
+        ...p,
+      };
+    }
   };
 
   store.setState(