feat(app-state): improve error message when trying to .assign() to …

…undefined state. Closes #53
simontonsoftware · Oct 2, 2021 · ad11531 · ad11531
1 parent 115b757
commit ad11531
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diff --git a/projects/app-state/src/lib/store.spec.ts b/projects/app-state/src/lib/store.spec.ts
@@ -227,6 +227,12 @@ describe('Store', () => {
       expect(store.state()).toBe(startingState);
       expect(cloneDeep(store.state())).toEqual(stateClone);
     });
+
+    it('throws with a useful message when the state is missing', () => {
+      expect(() => {
+        store<'optional', InnerState>('optional').assign({ state: 3 });
+      }).toThrowError('cannot assign to undefined state');
+    });
   });
 
   describe('.setUsing()', () => {

diff --git a/projects/app-state/src/lib/store.ts b/projects/app-state/src/lib/store.ts
@@ -70,6 +70,10 @@ export abstract class Store<T> extends CallableObject<GetSlice<T>> {
    */
   assign(value: Partial<T>): void {
     this.setUsing((state: any) => {
+      if (!state) {
+        throw new Error('cannot assign to undefined state');
+      }
+
       if (every(value, (innerValue, key) => state[key] === innerValue)) {
         return state;
       } else {