Add a test to verify adapter usage with createSlice

Author: markerikson

src/entities/entity_state.test.ts

@@ -1,4 +1,6 @@
 import { createEntityAdapter, EntityAdapter } from './index'
+import { PayloadAction, createAction } from '../createAction'
+import { createSlice } from '../createSlice'
 import { BookModel } from './fixtures/book'
 
 describe('Entity State', () => {
@@ -30,4 +32,45 @@ describe('Entity State', () => {
       entities: {}
     })
   })
+
+  it('should allow methods to be passed as reducers', () => {
+    const upsertBook = createAction<BookModel>('otherBooks/upsert')
+
+    const booksSlice = createSlice({
+      name: 'books',
+      initialState: adapter.getInitialState(),
+      reducers: {
+        addOne: adapter.addOne,
+        removeOne(state, action: PayloadAction<string>) {
+          return adapter.removeOne(state, action)
+        }
+      },
+      extraReducers: builder => {
+        builder.addCase(upsertBook, (state, action) => {
+          return adapter.upsertOne(state, action)
+        })
+      }
+    })
+
+    const { addOne, removeOne } = booksSlice.actions
+    const { reducer } = booksSlice
+
+    const selectors = adapter.getSelectors()
+
+    const book1: BookModel = { id: 'a', title: 'First' }
+    const book1a: BookModel = { id: 'a', title: 'Second' }
+
+    const afterAddOne = reducer(undefined, addOne(book1))
+    expect(afterAddOne.entities[book1.id]).toBe(book1)
+
+    const afterRemoveOne = reducer(afterAddOne, removeOne(book1.id))
+    expect(afterRemoveOne.entities[book1.id]).toBeUndefined()
+    expect(selectors.selectTotal(afterRemoveOne)).toBe(0)
+
+    const afterUpsertFirst = reducer(afterRemoveOne, upsertBook(book1))
+    const afterUpsertSecond = reducer(afterUpsertFirst, upsertBook(book1a))
+
+    expect(afterUpsertSecond.entities[book1.id]).toEqual(book1a)
+    expect(selectors.selectTotal(afterUpsertSecond)).toBe(1)
+  })
 })