From 1f079b883ebe0c595bd9960d50271d5b598e17a7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?G=C3=A9ry=20Debongnie?= <ged@odoo.com>
Date: Tue, 26 Nov 2019 22:51:35 +0100
Subject: [PATCH] [IMP] store: prevent changes to store state in useStore
 return value

closes #500
---
 doc/reference/store.md    |  3 +++
 src/store.ts              |  3 +--
 tests/store_hooks.test.ts | 18 ++++++++++++++++++
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/doc/reference/store.md b/doc/reference/store.md
index b35d6af1..aef98896 100644
--- a/doc/reference/store.md
+++ b/doc/reference/store.md
@@ -274,6 +274,9 @@ Note that if the selector function returns a primitive type, the result of
 is important to define the `onUpdate` option to properly update the value
 manually when it changes.
 
+Also, the return value from `useStore` is not supposed to be modified. The store
+state should only be updated with actions.
+
 ### `useDispatch`
 
 The `useDispatch` hook is useful when a component needs to be able to dispatch
diff --git a/src/store.ts b/src/store.ts
index 3a07c77d..5a469b03 100644
--- a/src/store.ts
+++ b/src/store.ts
@@ -134,8 +134,7 @@ export function useStore(selector, options: SelectorOptions = {}): any {
       return result[k];
     },
     set(target, k, v) {
-      result[k] = v;
-      return true;
+      throw new Error("Store state should only be modified through actions");
     }
   });
 }
diff --git a/tests/store_hooks.test.ts b/tests/store_hooks.test.ts
index d181d2f0..73360be6 100644
--- a/tests/store_hooks.test.ts
+++ b/tests/store_hooks.test.ts
@@ -100,6 +100,24 @@ describe("connecting a component to store", () => {
     expect(error.message).toBe("No store found when connecting 'App'");
   });
 
+  test("cannot modify state returned by usestore", async () => {
+    const state = { a: { b: 1 } };
+    const actions = {};
+    const store = new Store({ state, actions });
+
+    class App extends Component<any, any> {
+      static template = xml`<div/>`;
+      storeState = useStore(state => state.a);
+    }
+
+    (<any>env).store = store;
+    const app = new App();
+    expect(app.storeState.b).toBe(1);
+    expect(() => (app.storeState.b = 2)).toThrow(
+      "Store state should only be modified through actions"
+    );
+  });
+
   test("can use useStore twice in a component", async () => {
     const state = { a: 1, b: 2 };
     const actions = {