add unit tests

Author: george treviranus

README.md

@@ -86,9 +86,9 @@ Once a store is created, you'll be able to add subscriptions with `subscribe` an
 
 Here's a breakdown of each binding needed when initializing a new store:
 
-#### `reducer(type, state, payload = {})`
+#### `reducer(state, { type, payload } = action)`
 
-> `type (string)`: The action dispatched.<br/>`state (object)`: A copy of the current state object.<br/>`payload (object={})`: The payload given during dispatch.
+> `state (object)`: A copy of the current state object.<br/>`action ({ type, payload })`: The dispatched action type and its payload.
 
 Creates a new version of state and returns it, based on the `type` and `payload`. If the return value is falsy, nothing happens.
 

__tests__/core-flux.spec.js

@@ -0,0 +1,51 @@
+import { createStore } from "../core-flux"
+
+const testBindState = jest.fn()
+const testBindSubscriber = jest.fn()
+const testReducer = jest.fn()
+
+describe("createStore", () => {
+  let store,
+    data = "data",
+    subscriber = {},
+    type = "TEST_TYPE",
+    payload = {}
+
+  beforeAll(() => {
+    store = createStore({}, testReducer, testBindSubscriber, testBindState)
+  })
+
+  it("creates dispatch and subscribe helper functions", () => {
+    expect(store).toEqual(expect.any(Object))
+    expect(store.dispatch).toEqual(expect.any(Function))
+    expect(store.subscribe).toEqual(expect.any(Function))
+  })
+
+  it("calls subscriber binding when subscription is added", () => {
+    store.subscribe(subscriber, data)
+
+    expect(testBindSubscriber).toBeCalledWith(
+      expect.arrayContaining([subscriber, data]),
+      expect.any(Object)
+    )
+  })
+
+  it("calls reducer when dispatch is made", () => {
+    store.dispatch(type, payload)
+
+    expect(testReducer).toBeCalledWith(
+      expect.any(Object),
+      expect.objectContaining({ type, payload })
+    )
+  })
+
+  it("calls state binding when dispatch is made", () => {
+    store.dispatch(type, payload)
+
+    expect(testBindState).toBeCalledWith(
+      expect.arrayContaining([expect.arrayContaining([subscriber, data])]),
+      undefined,
+      expect.any(Function)
+    )
+  })
+})

core-flux.js

@@ -29,40 +29,30 @@ function clone(obj) {
   const isArray = Array.isArray(obj)
 
   let value,
-    newObj = isArray ? [] : {}
+    copyObj = isArray ? [] : {}
 
   if (isArray) {
     let length = obj.length,
       idx = -1
     while (++idx < length) {
-      newObj[idx] = obj[idx]
+      copyObj[idx] = obj[idx]
     }
   } else {
     for (const key in obj) {
       value = obj[key]
-      newObj[key] = newObj[key] =
+      copyObj[key] = copyObj[key] =
         value === null ? null : typeof value === "object" ? clone(value) : value
     }
   }
 
-  return newObj
+  return copyObj
 }
 
-/**
- * Append a new state object to a Store.
- * @param {string} id
- * @param {{}} initialState
- */
-function initState(id, initialState = {}) {
-  Stores[id].state = initialState
-}
-
-/**
- * Append a new subscriber array to a Store.
- * @param {string} id
- */
-function initSubscriptions(id) {
-  Stores[id].subscriptions = []
+function setInitialStore(id, initialState) {
+  Stores[id] = {
+    state: initialState,
+    subscriptions: [],
+  }
 }
 
 /**
@@ -88,21 +78,26 @@ function setState(id, nextState = {}) {
  * @param {Function} updater
  * @returns {{dispatch: Function, subscribe: Function}}
  */
-export function createStore(initialState, reducer, bindSubscriber, bindState) {
+export function createStore(
+  initialState = {},
+  reducer,
+  bindSubscriber,
+  bindState
+) {
   const id = createId()
-
-  Stores[id] = {}
-  initState(id, initialState)
-  initSubscriptions(id)
+  setInitialStore(id, initialState)
 
   return {
     dispatch(type, payload) {
       const state = getState(id)
-      const nextState = reducer(type, state, payload || {})
+      const reducedState = reducer(state, {
+        type,
+        payload: payload || {},
+      })
 
       return bindState(
         Stores[id].subscriptions,
-        nextState,
+        reducedState,
         function (rawNextState) {
           return setState(id, rawNextState)
         }
@@ -119,5 +114,6 @@ export function createStore(initialState, reducer, bindSubscriber, bindState) {
       const length = subscriptions.length
       bindSubscriber(subscriptions[length - 1], state)
     },
+    // data: Stores[id],
   }
 }