Added first test structure for ModelEventsAnalytics

no issue

- The added `ModelEventsAnalytics` class didn't have tests before the refactor. Added unit tests to verify functionality.

ghost/core/test/unit/server/services/segment/ModelEventsAnalytics.test.js

@@ -0,0 +1,108 @@
+const assert = require('assert');
+const sinon = require('sinon');
+
+// To test
+const ModelEventsAnalytics = require('../../../../../core/server/services/segment/ModelEventsAnalytics');
+
+// Stubbed dependencies
+const logging = require('@tryghost/logging');
+
+describe('ModelEventsAnalytics', function () {
+    describe('Constructor', function () {
+        it('doesn\'t throw', function () {
+            new ModelEventsAnalytics({});
+        });
+    });
+
+    describe('Model events analytics service', function () {
+        let modelEventsAnalytics;
+        let analyticsStub;
+        let sentryStub;
+        let loggingStub;
+
+        beforeEach(function () {
+            analyticsStub = sinon.stub();
+            sentryStub = sinon.stub();
+            loggingStub = sinon.stub(logging, 'error');
+        });
+
+        afterEach(function () {
+            sinon.restore();
+        });
+
+        it('subscribes to events', async function () {
+            modelEventsAnalytics = new ModelEventsAnalytics({
+                analytics: analyticsStub,
+                trackDefaults: {
+                    userId: '1234',
+                    properties: {email: 'john@test.com'}
+                },
+                prefix: 'Pro: ',
+                sentry: {
+                    captureException: sentryStub
+                }
+            });
+
+            modelEventsAnalytics.subscribeToModelEvents();
+            assert(loggingStub.callCount === 0);
+        });
+
+        it('handles milestone created event for 100 members', async function () {
+            modelEventsAnalytics = new ModelEventsAnalytics({
+                analytics: {
+                    track: analyticsStub
+                },
+                trackDefaults: {
+                    userId: '1234',
+                    properties: {email: 'john@test.com'}
+                },
+                prefix: 'Pro: ',
+                sentry: {
+                    captureException: sentryStub
+                }
+            });
+
+            modelEventsAnalytics.subscribeToModelEvents();
+
+            assert(analyticsStub.callCount === 1);
+            assert(analyticsStub.calledWith({
+                userId: '1234',
+                properties: {email: 'john@test.com'},
+                event: 'Pro: 100 members reached'
+            }));
+        });
+
+        it('handles milestone created event for $100 ARR', async function () {
+            modelEventsAnalytics = new ModelEventsAnalytics({
+                analytics: {
+                    track: analyticsStub
+                },
+                trackDefaults: {
+                    userId: '9876',
+                    properties: {email: 'john+arr@test.com'}
+                },
+                prefix: 'Pro: ',
+                sentry: {
+                    captureException: sentryStub
+                }
+            });
+
+            modelEventsAnalytics.subscribeToModelEvents();
+        });
+
+        it('can handle tracking errors', async function () {
+            let error = new Error('Test error');
+            modelEventsAnalytics = new ModelEventsAnalytics({
+                analytics: {
+                    track: analyticsStub.throws(error)
+                },
+                trackDefaults: {},
+                prefix: '',
+                sentry: {
+                    captureException: sentryStub
+                }
+            });
+
+            modelEventsAnalytics.subscribeToModelEvents();
+    });
+});