add selling_plan to cartAdd()

packages/theme-cart/__tests__/theme-cart.test.js

@@ -191,6 +191,21 @@ describe('addItem()', () => {
     );
   });
 
+  test('optional second argument is an object with a `selling_plan` key', async () => {
+    const spy = jest.spyOn(global, 'fetch');
+    const item = require('../__fixtures__/cart-populated.json').items[0];
+    const id = item.id;
+    const selling_plan = 1234;
+    const options = {selling_plan};
+
+    await cart.addItem(id, options);
+
+    expect(spy).toHaveBeenLastCalledWith(
+      '/cart/add.js',
+      expect.objectContaining({body: JSON.stringify({id, ...options})})
+    );
+  });
+
   test('returns a promise', () => {
     expect(cart.addItem(123456).then).toBeDefined();
   });

packages/theme-cart/request.js

@@ -23,19 +23,29 @@ export function cart() {
   return fetchJSON('/cart.js', getDefaultRequestConfig());
 }
 
-export function cartAdd(id, quantity, properties) {
+export function cartAdd(id, quantity, properties, selling_plan) {
   var config = getDefaultRequestConfig();
 
   config.method = 'POST';
   config.body = JSON.stringify({
     id: id,
     quantity: quantity,
+    selling_plan: selling_plan,
     properties: properties
   });
 
   return fetchJSON('/cart/add.js', config);
 }
 
+export function cartAddBulk(items) {
+  var config = getDefaultRequestConfig();
+
+  config.method = 'POST';
+  config.body = JSON.stringify({items});
+
+  return fetchJSON('/cart/add.js', config);
+}
+
 export function cartAddFromForm(formData) {
   var config = getDefaultRequestConfig();
   delete config.headers['Content-Type'];

packages/theme-cart/theme-cart.js

@@ -80,7 +80,13 @@ export function addItem(id, options) {
 
   validate.id(id);
 
-  return request.cartAdd(id, options.quantity, options.properties);
+  return request.cartAdd(id, options.quantity, options.properties, options.selling_plan);
+}
+
+export function addItems(items) {
+  items.forEach(({id}) => validate.id(id))
+
+  return request.cartAddBulk(items);
 }
 
 /**