new test for replaceReducers

Author: cellog

test/replaceReducers.spec.ts

@@ -0,0 +1,18 @@
+import { createStore, combineReducers } from '..'
+
+describe('replaceReducers test', () => {
+  it('returns the original store', () => {
+    const nextReducer = combineReducers({
+      foo: (state = 1, _action) => state,
+      bar: (state = 2, _action) => state
+    })
+    const store = createStore((state, action) => {
+      if (state === undefined) return 5
+      return action
+    })
+
+    const nextStore = store.replaceReducer(nextReducer)
+
+    expect(nextStore).toBe(store)
+  })
+})