ObjectCache reducer tests & docs

karma.conf.js

@@ -132,6 +132,10 @@ module.exports = function(config) {
       }
     },
 
+    mochaReporter: {
+      ignoreSkipped: true
+    }
+
     /*
      * Continuous Integration mode
      * if true, Karma captures browsers, runs the tests and exits

src/app/core/cache/object-cache.reducer.spec.ts

@@ -0,0 +1,101 @@
+import * as deepFreeze from "deep-freeze";
+import { objectCacheReducer } from "./object-cache.reducer";
+import {
+  AddToObjectCacheAction,
+  RemoveFromObjectCacheAction
+} from "./object-cache.actions";
+
+class NullAction extends RemoveFromObjectCacheAction {
+  type = null;
+  payload = null;
+
+  constructor() {
+    super(null);
+  }
+}
+
+describe("objectCacheReducer", () => {
+  const uuid = '1698f1d3-be98-4c51-9fd8-6bfedcbd59b7';
+  const testState = {
+    [uuid]: {
+      data: {
+        uuid: uuid,
+        foo: "bar"
+      },
+      timeAdded: new Date().getTime(),
+      msToLive: 900000
+    }
+  };
+  deepFreeze(testState);
+
+  it("should return the current state when no valid actions have been made", () => {
+    const action = new NullAction();
+    const newState = objectCacheReducer(testState, action);
+
+    expect(newState).toEqual(testState);
+  });
+
+  it("should start with an empty cache", () => {
+    const action = new NullAction();
+    const initialState = objectCacheReducer(undefined, action);
+
+    expect(initialState).toEqual(Object.create(null));
+  });
+
+  it("should add the payload to the cache in response to an ADD action", () => {
+    const state = Object.create(null);
+    const objectToCache = {uuid: uuid};
+    const timeAdded = new Date().getTime();
+    const msToLive = 900000;
+    const action = new AddToObjectCacheAction(objectToCache, timeAdded, msToLive);
+    const newState = objectCacheReducer(state, action);
+
+    expect(newState[uuid].data).toEqual(objectToCache);
+    expect(newState[uuid].timeAdded).toEqual(timeAdded);
+    expect(newState[uuid].msToLive).toEqual(msToLive);
+  });
+
+  it("should overwrite an object in the cache in response to an ADD action if it already exists", () => {
+    const objectToCache = {uuid: uuid, foo: "baz", somethingElse: true};
+    const timeAdded = new Date().getTime();
+    const msToLive = 900000;
+    const action = new AddToObjectCacheAction(objectToCache, timeAdded, msToLive);
+    const newState = objectCacheReducer(testState, action);
+
+    expect(newState[uuid].data['foo']).toBe("baz");
+    expect(newState[uuid].data['somethingElse']).toBe(true);
+  });
+
+  it("should perform the ADD action without affecting the previous state", () => {
+    const state = Object.create(null);
+    const objectToCache = {uuid: uuid};
+    const timeAdded = new Date().getTime();
+    const msToLive = 900000;
+    const action = new AddToObjectCacheAction(objectToCache, timeAdded, msToLive);
+    deepFreeze(state);
+
+    objectCacheReducer(state, action);
+  });
+
+  it("should remove the specified object from the cache in response to the REMOVE action", () => {
+    const action = new RemoveFromObjectCacheAction(uuid);
+    const newState = objectCacheReducer(testState, action);
+
+    expect(testState[uuid]).not.toBeUndefined();
+    expect(newState[uuid]).toBeUndefined();
+  });
+
+  it("shouldn't do anything in response to the REMOVE action for an object that isn't cached", () => {
+    const action = new RemoveFromObjectCacheAction("this isn't cached");
+    const newState = objectCacheReducer(testState, action);
+
+    expect(newState).toEqual(testState);
+  });
+
+  it("should perform the REMOVE action without affecting the previous state", () => {
+    const action = new RemoveFromObjectCacheAction(uuid);
+    //testState has already been frozen above
+    objectCacheReducer(testState, action);
+  });
+
+});

src/app/core/cache/object-cache.reducer.ts

@@ -2,16 +2,30 @@ import { ObjectCacheAction, ObjectCacheActionTypes, AddToObjectCacheAction, Remo
 import { hasValue } from "../../shared/empty.util";
 import { CacheEntry } from "./cache-entry";
 
+/**
+ * An interface to represent objects that can be cached
+ *
+ * A cacheable object should have a uuid
+ */
 export interface CacheableObject {
   uuid: string;
 }
 
+/**
+ * An entry in the ObjectCache
+ */
 export class ObjectCacheEntry implements CacheEntry {
   data: CacheableObject;
   timeAdded: number;
   msToLive: number;
 }
 
+/**
+ * The ObjectCache State
+ *
+ * Consists of a map with UUIDs as keys,
+ * and ObjectCacheEntries as values
+ */
 export interface ObjectCacheState {
   [uuid: string]: ObjectCacheEntry
 }
@@ -19,6 +33,16 @@ export interface ObjectCacheState {
 // Object.create(null) ensures the object has no default js properties (e.g. `__proto__`)
 const initialState: ObjectCacheState = Object.create(null);
 
+/**
+ * The ObjectCache Reducer
+ *
+ * @param state
+ *    the current state
+ * @param action
+ *    the action to perform on the state
+ * @return ObjectCacheState
+ *    the new state
+ */
 export const objectCacheReducer = (state = initialState, action: ObjectCacheAction): ObjectCacheState => {
   switch (action.type) {
 
@@ -36,6 +60,16 @@ export const objectCacheReducer = (state = initialState, action: ObjectCacheActi
   }
 };
 
+/**
+ * Add an object to the cache
+ *
+ * @param state
+ *    the current state
+ * @param action
+ *    an AddToObjectCacheAction
+ * @return ObjectCacheState
+ *    the new state, with the object added, or overwritten.
+ */
 function addToObjectCache(state: ObjectCacheState, action: AddToObjectCacheAction): ObjectCacheState {
   return Object.assign({}, state, {
     [action.payload.objectToCache.uuid]: {
@@ -46,6 +80,16 @@ function addToObjectCache(state: ObjectCacheState, action: AddToObjectCacheActio
   });
 }
 
+/**
+ * Remove an object from the cache
+ *
+ * @param state
+ *    the current state
+ * @param action
+ *    an RemoveFromObjectCacheAction
+ * @return ObjectCacheState
+ *    the new state, with the object removed if it existed.
+ */
 function removeFromObjectCache(state: ObjectCacheState, action: RemoveFromObjectCacheAction): ObjectCacheState {
   if (hasValue(state[action.payload])) {
     let newObjectCache = Object.assign({}, state);