Fixed undefined error when serializing webhooks

closes: https://github.com/TryGhost/Toolbox/issues/318
refs: https://github.com/TryGhost/Toolbox/issues/320
refs: 2a11d5100e

- The underlying problem was caused by the removal of API versions
  - commit 2a11d5100e
  - I missed doing the same refactor as was done for the post-emailserializer here: 2a11d5100e (diff-0f7477bb5e5a9fdcb4c909a9e9e61ab5bb76b640b2d63a5791a9d6c8904f2758R7)
  - The removal of api versions included a change to remove circular references in the api module
- Written some basic unit tests to prove that webhook serialization works
  - I'm not 100% happy with the output, and not sure if it's the tests or reality, needs further work
  - Future work tracked in https://github.com/TryGhost/Toolbox/issues/320

core/server/services/webhooks/serialize.js

@@ -2,6 +2,7 @@ module.exports = (event, model) => {
     const _ = require('lodash');
     const {sequence} = require('@tryghost/promise');
     const api = require('../../api').endpoints;
+    const apiShared = require('../../api').shared;
 
     const resourceName = event.match(/(\w+)\./)[1];
     const docName = `${resourceName}s`;
@@ -17,7 +18,7 @@ module.exports = (event, model) => {
                 frame.options.withRelated = ['tags', 'authors'];
             }
 
-            return api.shared
+            return apiShared
                 .serializers
                 .handle
                 .output(model, {docName: docName, method: 'read'}, api.serializers.output, frame)
@@ -40,7 +41,7 @@ module.exports = (event, model) => {
                 frame.options.withRelated = ['tags', 'authors'];
             }
 
-            return api.shared
+            return apiShared
                 .serializers
                 .handle
                 .output(model, {docName: docName, method: 'read'}, api.serializers.output, frame)

test/unit/server/services/webhooks/serialize.test.js

@@ -0,0 +1,83 @@
+const sinon = require('sinon');
+const assert = require('assert');
+
+const models = require('../../../../../core/server/models');
+
+const serialize = require('../../../../../core/server/services/webhooks/serialize');
+
+// Mocked internals
+const membersService = require('../../../../../core/server/services/members');
+
+const {fixtureManager} = require('../../../../utils/e2e-framework');
+
+describe('WebhookService - Serialize', function () {
+    before(function () {
+        models.init();
+    });
+
+    beforeEach(function () {
+        sinon.stub(membersService, 'api').get(() => {
+            return {
+                productRepository: {
+                    list: sinon.stub().returns({})
+                }
+            };
+        });
+    });
+
+    it('rejects with no arguments', async function () {
+        assert.rejects(await serialize, {name: 'TypeError'});
+    });
+
+    it('rejects with no model', async function () {
+        await assert.rejects(
+            async () => {
+                await serialize('fake.hook');
+            },
+            (error) => {
+                assert.strictEqual(error.name, 'TypeError');
+                assert.strictEqual(error.message, 'Cannot read properties of undefined (reading \'attributes\')');
+                return true;
+            }
+        );
+    });
+
+    it('can serialize a basic model', async function () {
+        const fakeModel = {
+            attributes: {},
+            _previousAttributes: {}
+        };
+
+        const result = await serialize('test.hook', fakeModel);
+        assert.deepEqual(result, {test: {current: {}, previous: {}}});
+    });
+
+    it('can serialize a new post', async function () {
+        const post = fixtureManager.get('posts', 1);
+        const postModel = new models.Post(post);
+
+        const result = await serialize('post.added', postModel);
+
+        assert.ok(result.post, 'Should be wrapped in post');
+        assert.deepEqual(result.post.previous, {});
+        // @TODO: use snapshot matching here
+        assert.equal(result.post.current.reading_time, 1, 'The reading time generated field should be present');
+    });
+
+    it('can serialize an edited post', async function () {
+        const post = fixtureManager.get('posts', 1);
+        const postModel = new models.Post(post);
+
+        // We use both _previousAttributes and _changed in the webhook serializer
+        postModel._previousAttributes.title = post.title;
+        postModel._changed = {title: post.title};
+        postModel.attributes.title = 'A brand new title';
+
+        const result = await serialize('post.edited', postModel);
+
+        assert.ok(result.post, 'Should be wrapped in post');
+        // @TODO: use snapshot matching here
+        assert.equal(result.post.current.title, 'A brand new title', 'The updated title should be present');
+        assert.equal(result.post.previous.title, 'Ghostly Kitchen Sink', 'The previous title should also be present');
+    });
+});