Paypal refactor lib (#8420)

* Abstracted paypal logic from controller. Added intial tests

* Added checkout tests

* Added checkout success test

* Added subscribe test

* Added subscribeSuccess tests

* Added subscribeCancel tests

* Added ipn tests

* Fixed broken test

* Added integration tests and fixed linting issues

* Added errors for paypal checkout success integration test

* Removed extra test

* Removed pending status from subscribe cancel test

* Added more error checking and tests

* Fixed lint issues

test/api/v3/integration/payments/paypal/GET-payments_paypal_checkout.test.js

@@ -0,0 +1,40 @@
+import {
+  generateUser,
+} from '../../../../../helpers/api-integration/v3';
+import paypalPayments from '../../../../../../website/server/libs/paypalPayments';
+
+describe('payments : paypal #checkout', () => {
+  let endpoint = '/paypal/checkout';
+  let user;
+
+  beforeEach(async () => {
+    user = await generateUser();
+  });
+
+  describe('success', () => {
+    let checkoutStub;
+
+    beforeEach(async () => {
+      checkoutStub = sinon.stub(paypalPayments, 'checkout').returnsPromise().resolves('/');
+    });
+
+    afterEach(() => {
+      paypalPayments.checkout.restore();
+    });
+
+    it('creates a purchase link', async () => {
+      user = await generateUser({
+        'profile.name': 'sender',
+        'purchased.plan.customerId': 'customer-id',
+        'purchased.plan.planId': 'basic_3mo',
+        'purchased.plan.lastBillingDate': new Date(),
+        balance: 2,
+      });
+
+      await user.get(endpoint);
+
+      expect(checkoutStub).to.be.calledOnce;
+      expect(checkoutStub.args[0][0].gift).to.eql(undefined);
+    });
+  });
+});