CHECKOUT-2507: Convert DataStore module into TypeScript

package.json

@@ -31,7 +31,9 @@
     "precompile": "rm -rf lib",
     "compile": "tsc --outDir lib",
     "compile:watch": "yarn compile -- --watch",
-    "lint": "eslint src --config eslintrc.json",
+    "lint": "yarn lint:js && yarn lint:ts",
+    "lint:js": "eslint src --config eslintrc.json",
+    "lint:ts": "tslint src/**/*.ts --config tslint.json",
     "prerelease": "git fetch --tags && yarn validate-dependencies && yarn validate-commits && yarn build",
     "release": "git add dist lib && standard-version -a",
     "test": "jest --config jest-config.js",
@@ -44,6 +46,8 @@
   },
   "dependencies": {
     "@bigcommerce/request-sender": "git+ssh://git@github.com/bigcommerce/request-sender-js.git#0.1.0",
+    "@types/jest": "^21.1.10",
+    "@types/lodash": "^4.14.92",
     "bigpay-client": "git+ssh://git@github.com/bigcommerce-labs/bigpay-client-js.git#2.9.1",
     "form-poster": "git+ssh://git@github.com/bigcommerce-labs/form-poster-js.git#1.1.1",
     "lodash": "^4.17.4",
@@ -60,6 +64,7 @@
     "standard-version": "^4.2.0",
     "ts-jest": "^21.2.3",
     "ts-loader": "^3.2.0",
+    "tslint": "^5.9.1",
     "typescript": "^2.6.2",
     "typescript-eslint-parser": "^9.0.1",
     "uglifyjs-webpack-plugin": "^1.1.1",

src/data-store/action.ts

@@ -0,0 +1,6 @@
+export default interface Action<TPayload = any, TMeta = any> {
+    type: string;
+    error?: boolean;
+    meta?: TMeta;
+    payload?: TPayload;
+}

src/data-store/combine-reducers.ts

@@ -0,0 +1,23 @@
+import Action from './action';
+import Reducer from './reducer';
+
+export default function combineReducers<TState, TAction extends Action>(
+    reducers: ReducerMap<TState, TAction>
+): Reducer<TState, TAction> {
+    return (state, action) =>
+        Object.keys(reducers).reduce((result: TState, key) => {
+            const reducer = reducers[key as keyof TState];
+            const currentState = state ? state[key as keyof TState] : undefined;
+            const newState = reducer(currentState, action);
+
+            if (currentState === newState && result) {
+                return result;
+            }
+
+            return Object.assign({}, result, { [key]: newState });
+        }, state);
+}
+
+export type ReducerMap<TState, TAction extends Action> = {
+    [Key in keyof TState]: Reducer<TState[Key], TAction>;
+};

src/data-store/compose-reducers.spec.js → src/data-store/compose-reducers.spec.ts

@@ -1,7 +1,7 @@
 import composeReducers from './compose-reducers';
 
 describe('composeReducers()', () => {
-    const fooReducer = (state, action) => {
+    const fooReducer = (state = '', action) => {
         switch (action.type) {
         case 'FOO':
             return 'foo';
@@ -14,7 +14,7 @@ describe('composeReducers()', () => {
         }
     };
 
-    const barReducer = (state, action) => {
+    const barReducer = (state = '', action) => {
         switch (action.type) {
         case 'BAR':
             return 'bar';

src/data-store/compose-reducers.ts

@@ -0,0 +1,13 @@
+import { curryRight, flowRight } from 'lodash';
+import Action from './action';
+import Reducer from './reducer';
+
+export default function composeReducers<TState, TAction extends Action>(
+    ...reducers: Array<Reducer<Partial<TState>, TAction>>
+): Reducer<TState, TAction> {
+    return (state, action) =>
+        flowRight.apply(
+            null,
+            reducers.map(reducer => curryRight(reducer)(action))
+        )(state);
+}

src/data-store/create-action.spec.js → src/data-store/create-action.spec.ts

@@ -15,7 +15,7 @@ describe('createAction()', () => {
         expect(action).toEqual({ type: 'ACTION' });
     });
 
-    it('throws an error if `type` is not provided', () => {
-        expect(() => createAction()).toThrow();
+    it('throws an error if `type` is not provided or empty', () => {
+        expect(() => createAction('')).toThrow();
     });
 });

src/data-store/create-action.ts

@@ -0,0 +1,14 @@
+import { omitBy } from 'lodash';
+import Action from './action';
+
+export default function createAction<TPayload, TMeta>(
+    type: string,
+    payload?: TPayload,
+    meta?: TMeta
+): Action<TPayload, TMeta> {
+    if (typeof type !== 'string' || type === '') {
+        throw new Error('`type` must be a string');
+    }
+
+    return { type, ...omitBy({ payload, meta }, value => value === undefined) };
+}

src/data-store/create-data-store.ts

@@ -0,0 +1,16 @@
+import Action from './action';
+import combineReducers, { ReducerMap } from './combine-reducers';
+import DataStore, { DataStoreOptions } from './data-store';
+import Reducer from './reducer';
+
+export default function createDataStore<TState, TAction extends Action, TTransformedState = TState>(
+    reducer: Reducer<Partial<TState>, TAction> | ReducerMap<Partial<TState>, TAction>,
+    initialState: Partial<TState>,
+    options: DataStoreOptions<TState, TAction, TTransformedState>
+): DataStore<TState, TAction, TTransformedState> {
+    if (typeof reducer === 'function') {
+        return new DataStore(reducer, initialState, options);
+    }
+
+    return new DataStore(combineReducers(reducer), initialState, options);
+}

src/data-store/create-error-action.spec.js → src/data-store/create-error-action.spec.ts

@@ -15,7 +15,7 @@ describe('createErrorAction()', () => {
         expect(action).toEqual({ type: 'ACTION', error: true });
     });
 
-    it('throws an error if `type` is not provided', () => {
-        expect(() => createErrorAction()).toThrow();
+    it('throws an error if `type` is not provided or empty', () => {
+        expect(() => createErrorAction('')).toThrow();
     });
 });

src/data-store/create-error-action.ts

@@ -0,0 +1,13 @@
+import Action from './action';
+import createAction from './create-action';
+
+export default function createErrorAction<TPayload, TMeta>(
+    type: string,
+    payload?: TPayload,
+    meta?: TMeta
+): Action<TPayload, TMeta> {
+    return {
+        ...createAction(type, payload, meta),
+        error: true,
+    };
+}

src/data-store/data-store.spec.js → src/data-store/data-store.spec.ts

@@ -1,4 +1,5 @@
 import { Observable } from 'rxjs';
+import Action from './action';
 import DataStore from './data-store';
 
 describe('DataStore', () => {
@@ -31,7 +32,7 @@ describe('DataStore', () => {
 
         it('dispatches error actions and rejects with payload', async () => {
             const store = new DataStore(state => state);
-            const action = { error: true, payload: 'foobar' };
+            const action = { type: 'FOOBAR', error: true, payload: 'foobar' };
 
             try {
                 await store.dispatch(action);
@@ -52,7 +53,7 @@ describe('DataStore', () => {
             expect(await store.dispatch(Observable.of(
                 { type: 'APPEND', payload: 'foo' },
                 { type: 'APPEND', payload: 'bar' },
-                { type: 'APPEND', payload: '!!!' },
+                { type: 'APPEND', payload: '!!!' }
             ))).toEqual({ message: 'foobar!!!' });
         });
 
@@ -156,8 +157,8 @@ describe('DataStore', () => {
             const store = new DataStore(reducer);
 
             reducer.mockClear();
-            store.dispatch({});
-            store.dispatch({ payload: 'foobar' });
+            store.dispatch({ type: '' });
+            store.dispatch({ type: '', payload: 'foobar' });
 
             expect(reducer).not.toHaveBeenCalled();
         });
@@ -167,7 +168,7 @@ describe('DataStore', () => {
             const store = new DataStore(reducer);
 
             reducer.mockClear();
-            store.dispatch(Observable.of({}, { payload: 'foobar' }));
+            store.dispatch(Observable.of({ type: '', payload: 'foo' }, { type: '', payload: 'bar' }));
 
             expect(reducer).not.toHaveBeenCalled();
         });
@@ -290,7 +291,7 @@ describe('DataStore', () => {
                 default:
                     return state;
                 }
-            });
+            }, { foo: '', bar: '' });
             const subscriber = jest.fn();
 
             store.subscribe(subscriber, (state) => state.foo);
@@ -323,7 +324,7 @@ describe('DataStore', () => {
                 default:
                     return state;
                 }
-            });
+            }, { foo: '', bar: '', foobar: '' });
             const subscriber = jest.fn();
 
             store.subscribe(