From 40459057a0de958dcf36c4af31b192a0f73ff9e0 Mon Sep 17 00:00:00 2001
From: Andrew Duthie <andrew@andrewduthie.com>
Date: Fri, 20 Jul 2018 17:16:50 -0400
Subject: [PATCH] Core Data: Partially reimplement resolvers as controls

---
 packages/core-data/src/actions.js        | 16 ++++++++++++++++
 packages/core-data/src/controls.js       | 16 ++++++++++++++++
 packages/core-data/src/index.js          |  2 ++
 packages/core-data/src/resolvers.js      | 13 +++++++------
 packages/core-data/src/test/resolvers.js | 22 +++++++++++-----------
 5 files changed, 52 insertions(+), 17 deletions(-)
 create mode 100644 packages/core-data/src/controls.js

diff --git a/packages/core-data/src/actions.js b/packages/core-data/src/actions.js
index 31107d8daef10..3f550becca66e 100644
--- a/packages/core-data/src/actions.js
+++ b/packages/core-data/src/actions.js
@@ -3,6 +3,22 @@
  */
 import { castArray } from 'lodash';
 
+/**
+ * Given an apiFetch payload, returns an action object used in signalling that
+ * an API request should be issued. This can be used in tandem with the data
+ * module's `controls` option for asynchronous API request logic flows.
+ *
+ * @param {Object} options apiFetch options payload.
+ *
+ * @return {Object} Action object.
+ */
+export function fetchFromAPI( options ) {
+	return {
+		type: 'FETCH_FROM_API',
+		...options,
+	};
+}
+
 /**
  * Returns an action object used in signalling that terms have been received
  * for a given taxonomy.
diff --git a/packages/core-data/src/controls.js b/packages/core-data/src/controls.js
new file mode 100644
index 0000000000000..981533d5b101e
--- /dev/null
+++ b/packages/core-data/src/controls.js
@@ -0,0 +1,16 @@
+/**
+ * WordPress dependencies
+ */
+import apiFetch from '@wordpress/api-fetch';
+
+/**
+ * Given an action object, triggers an API request to retrieve the result from
+ * the given action path.
+ *
+ * @param {Object} action Fetch action object.
+ *
+ * @return {Promise} Fetch promise.
+ */
+export function FETCH_FROM_API( action ) {
+	return apiFetch( { path: action.path } );
+}
diff --git a/packages/core-data/src/index.js b/packages/core-data/src/index.js
index 31fe114746930..ae1d4a2adece5 100644
--- a/packages/core-data/src/index.js
+++ b/packages/core-data/src/index.js
@@ -10,6 +10,7 @@ import reducer from './reducer';
 import * as selectors from './selectors';
 import * as actions from './actions';
 import * as resolvers from './resolvers';
+import * as controls from './controls';
 import { defaultEntities, getMethodName } from './entities';
 import { REDUCER_KEY } from './name';
 
@@ -26,6 +27,7 @@ const entitySelectors = createEntityRecordGetter( selectors );
 const store = registerStore( REDUCER_KEY, {
 	reducer,
 	actions,
+	controls,
 	selectors: { ...selectors, ...entitySelectors },
 	resolvers: { ...resolvers, ...entityResolvers },
 } );
diff --git a/packages/core-data/src/resolvers.js b/packages/core-data/src/resolvers.js
index a105997bfedd6..a267257012eaf 100644
--- a/packages/core-data/src/resolvers.js
+++ b/packages/core-data/src/resolvers.js
@@ -12,6 +12,7 @@ import apiFetch from '@wordpress/api-fetch';
  * Internal dependencies
  */
 import {
+	fetchFromAPI,
 	receiveTerms,
 	receiveUserQuery,
 	receiveEntityRecords,
@@ -23,16 +24,16 @@ import { getKindEntities } from './entities';
  * Requests categories from the REST API, yielding action objects on request
  * progress.
  */
-export async function* getCategories() {
-	const categories = await apiFetch( { path: '/wp/v2/categories?per_page=-1' } );
+export function* getCategories() {
+	const categories = yield fetchFromAPI( { path: '/wp/v2/categories?per_page=-1' } );
 	yield receiveTerms( 'categories', categories );
 }
 
 /**
  * Requests authors from the REST API.
  */
-export async function* getAuthors() {
-	const users = await apiFetch( { path: '/wp/v2/users/?who=authors&per_page=-1' } );
+export function* getAuthors() {
+	const users = yield fetchFromAPI( { path: '/wp/v2/users/?who=authors&per_page=-1' } );
 	yield receiveUserQuery( 'authors', users );
 }
 
@@ -74,7 +75,7 @@ export async function* getEntityRecords( state, kind, name ) {
 /**
  * Requests theme supports data from the index.
  */
-export async function* getThemeSupports() {
-	const index = await apiFetch( { path: '/' } );
+export function* getThemeSupports() {
+	const index = yield fetchFromAPI( { path: '/' } );
 	yield receiveThemeSupportsFromIndex( index );
 }
diff --git a/packages/core-data/src/test/resolvers.js b/packages/core-data/src/test/resolvers.js
index 29f0cf68bf271..5d31a137355e4 100644
--- a/packages/core-data/src/test/resolvers.js
+++ b/packages/core-data/src/test/resolvers.js
@@ -7,25 +7,25 @@ import apiFetch from '@wordpress/api-fetch';
  * Internal dependencies
  */
 import { getCategories, getEntityRecord, getEntityRecords } from '../resolvers';
-import { receiveTerms, receiveEntityRecords, addEntities } from '../actions';
+import {
+	fetchFromAPI,
+	receiveTerms,
+	receiveEntityRecords,
+	addEntities,
+} from '../actions';
 
 jest.mock( '@wordpress/api-fetch' );
 
 describe( 'getCategories', () => {
 	const CATEGORIES = [ { id: 1 } ];
 
-	beforeAll( () => {
-		apiFetch.mockImplementation( ( options ) => {
-			if ( options.path === '/wp/v2/categories?per_page=-1' ) {
-				return Promise.resolve( CATEGORIES );
-			}
-		} );
-	} );
-
 	it( 'yields with requested terms', async () => {
 		const fulfillment = getCategories();
-		const received = ( await fulfillment.next() ).value;
-		expect( received ).toEqual( receiveTerms( 'categories', CATEGORIES ) );
+		let yielded;
+		yielded = fulfillment.next().value;
+		expect( yielded.type ).toBe( fetchFromAPI().type );
+		yielded = fulfillment.next( CATEGORIES ).value;
+		expect( yielded ).toEqual( receiveTerms( 'categories', CATEGORIES ) );
 	} );
 } );