diff --git a/spec/main.spec.ts b/spec/main.spec.ts
index ccc4193..d34d79c 100644
--- a/spec/main.spec.ts
+++ b/spec/main.spec.ts
@@ -24,15 +24,8 @@ import { expect } from 'chai';
 import * as functions from 'firebase-functions';
 import { set } from 'lodash';
 
-import {
-  mockConfig,
-  makeChange,
-  wrap,
-} from '../src/main';
-import {
-  _makeResourceName,
-  _extractParams,
-} from '../src/v1';
+import { mockConfig, makeChange, wrap } from '../src/main';
+import { _makeResourceName, _extractParams } from '../src/v1';
 import { features } from '../src/features';
 import { FirebaseFunctionsTest } from '../src/lifecycle';
 import { alerts } from 'firebase-functions/v2';
diff --git a/spec/v2.spec.ts b/spec/v2.spec.ts
index d605a4c..d2f133c 100644
--- a/spec/v2.spec.ts
+++ b/spec/v2.spec.ts
@@ -134,11 +134,12 @@ describe('v2', () => {
     describe('storage', () => {
       describe('storage.onObjectArchived()', () => {
         it('should update CloudEvent appropriately', () => {
-          const bucket = 'bucket';
+          const bucket = 'bucket_override';
           const cloudFn = storage.onObjectArchived(bucket, handler);
           const cloudFnWrap = wrapV2(cloudFn);
           expect(cloudFnWrap().cloudEvent).to.include({
             bucket,
+            source: `//storage.googleapis.com/projects/_/buckets/${bucket}`,
           });
         });
       });
@@ -180,8 +181,21 @@ describe('v2', () => {
           const cloudFn = pubsub.onMessagePublished('topic', handler);
           const cloudFnWrap = wrapV2(cloudFn);
 
-          expect(cloudFnWrap().cloudEvent.data.message).to.include({
-            data: 'eyJoZWxsbyI6IndvcmxkIn0=', // Note: Defined in the partial
+          const message = cloudFnWrap().cloudEvent.data.message;
+          const data = message.data;
+          const json = JSON.parse(Buffer.from(data, 'base64').toString('utf8'));
+          expect(message).deep.equal({
+            // Mock data (can be overridden)
+            attributes: {
+              'sample-attribute': 'I am an attribute',
+            },
+            messageId: 'message_id',
+
+            // Recapture publish time (since it's generated during runtime)
+            publishTime: message.publishTime,
+
+            // Assertions on Expected Updates
+            data: Buffer.from(JSON.stringify(json)).toString('base64'),
           });
         });
         it('should update CloudEvent with json data override', () => {
@@ -195,14 +209,24 @@ describe('v2', () => {
           const cloudFnWrap = wrapV2(cloudFn);
           const cloudEventPartial = { data };
 
-          expect(
-            cloudFnWrap(cloudEventPartial).cloudEvent.data.message
-          ).to.include({
-            data: 'eyJoZWxsbyI6IndvcmxkIn0=', // Note: This is a mismatch from the json
+          const message = cloudFnWrap(cloudEventPartial).cloudEvent.data
+            .message;
+          expect(message).deep.equal({
+            // Mock data (can be overridden)
+            attributes: {
+              'sample-attribute': 'I am an attribute',
+            },
+            messageId: 'message_id',
+
+            // Recapture publish time (since it's generated during runtime)
+            publishTime: message.publishTime,
+
+            // Assertions on Expected Updates
+            data: Buffer.from(JSON.stringify(data.message.json)).toString(
+              'base64'
+            ),
+            json: { firebase: 'test' },
           });
-          expect(
-            cloudFnWrap(cloudEventPartial).cloudEvent.data.message.json
-          ).to.include({ firebase: 'test' });
         });
         it('should update CloudEvent with json and data string overrides', () => {
           const data = {
@@ -216,14 +240,24 @@ describe('v2', () => {
           const cloudFnWrap = wrapV2(cloudFn);
           const cloudEventPartial = { data };
 
-          expect(
-            cloudFnWrap(cloudEventPartial).cloudEvent.data.message
-          ).to.include({
-            data: 'eyJmaXJlYmFzZSI6Im5vbl9qc29uX3Rlc3QifQ==',
+          const message = cloudFnWrap(cloudEventPartial).cloudEvent.data
+            .message;
+          expect(message).deep.equal({
+            // Mock data (can be overridden)
+            attributes: {
+              'sample-attribute': 'I am an attribute',
+            },
+            messageId: 'message_id',
+
+            // Recapture publish time (since it's generated during runtime)
+            publishTime: message.publishTime,
+
+            // Assertions on Expected Updates
+            data: Buffer.from(JSON.stringify(data.message.json)).toString(
+              'base64'
+            ),
+            json: data.message.json,
           });
-          expect(
-            cloudFnWrap(cloudEventPartial).cloudEvent.data.message.json
-          ).to.include({ firebase: 'non_json_test' });
         });
       });
     });
diff --git a/src/cloudevent/generate.ts b/src/cloudevent/generate.ts
index fffafa2..908648b 100644
--- a/src/cloudevent/generate.ts
+++ b/src/cloudevent/generate.ts
@@ -1,9 +1,8 @@
 import { CloudEvent } from 'firebase-functions/v2';
 import { CloudFunction } from 'firebase-functions/v2';
-import { LIST_OF_MOCK_CLOUD_EVENT_PARTIALS } from './partials/partials';
-import { DeepPartial, MockCloudEventPartials } from './types';
+import { LIST_OF_MOCK_CLOUD_EVENT_PARTIALS } from './mocks/partials';
+import { DeepPartial, MockCloudEventAbstractFactory } from './types';
 import merge from 'ts-deepmerge';
-import { getEventType } from './partials/helpers';
 
 /**
  * @return {CloudEvent} Generated Mock CloudEvent
@@ -14,61 +13,27 @@ export function generateCombinedCloudEvent<
   cloudFunction: CloudFunction<EventType>,
   cloudEventPartial?: DeepPartial<EventType>
 ): EventType {
-  const generatedCloudEvent = generateMockCloudEvent(cloudFunction);
+  const generatedCloudEvent = generateMockCloudEvent(
+    cloudFunction,
+    cloudEventPartial
+  );
   return cloudEventPartial
     ? (merge(generatedCloudEvent, cloudEventPartial) as EventType)
     : generatedCloudEvent;
 }
 
 export function generateMockCloudEvent<EventType extends CloudEvent<unknown>>(
-  cloudFunction: CloudFunction<EventType>
-): EventType {
-  return {
-    ...generateBaseCloudEvent(cloudFunction),
-    ...generateMockCloudEventPartial(cloudFunction),
-  };
-}
-
-/** @internal */
-function generateBaseCloudEvent<EventType extends CloudEvent<unknown>>(
-  cloudFunction: CloudFunction<EventType>
+  cloudFunction: CloudFunction<EventType>,
+  cloudEventPartial?: DeepPartial<EventType>
 ): EventType {
-  // TODO: Consider refactoring so that we don't use this utility function. This
-  // is not type safe because EventType may require additional fields, which this
-  // function does not know how to satisfy.
-  // This could possibly be augmented to take a CloudEvent<unknown> and AdditionalFields<EventType>
-  // where AdditionalFields uses the keyof operator to make only new fields required.
-  return {
-    specversion: '1.0',
-    id: makeEventId(),
-    data: {},
-    source: '', // Required field that will get overridden by Provider-specific MockCloudEventPartials
-    type: getEventType(cloudFunction),
-    time: new Date().toISOString(),
-  } as any;
-}
-
-function generateMockCloudEventPartial<EventType extends CloudEvent<unknown>>(
-  cloudFunction: CloudFunction<EventType>
-): DeepPartial<EventType> {
   for (const mockCloudEventPartial of LIST_OF_MOCK_CLOUD_EVENT_PARTIALS) {
     if (mockCloudEventPartial.match(cloudFunction)) {
-      return (mockCloudEventPartial as MockCloudEventPartials<
-        EventType
-      >).generatePartial(cloudFunction);
+      return mockCloudEventPartial.generateMock(
+        cloudFunction,
+        cloudEventPartial
+      );
     }
   }
   // No matches were found
-  return {};
-}
-
-function makeEventId(): string {
-  return (
-    Math.random()
-      .toString(36)
-      .substring(2, 15) +
-    Math.random()
-      .toString(36)
-      .substring(2, 15)
-  );
+  return null;
 }
diff --git a/src/cloudevent/partials/alerts/alerts-on-alert-published.ts b/src/cloudevent/mocks/alerts/alerts-on-alert-published.ts
similarity index 63%
rename from src/cloudevent/partials/alerts/alerts-on-alert-published.ts
rename to src/cloudevent/mocks/alerts/alerts-on-alert-published.ts
index 1ca941d..a13c371 100644
--- a/src/cloudevent/partials/alerts/alerts-on-alert-published.ts
+++ b/src/cloudevent/mocks/alerts/alerts-on-alert-published.ts
@@ -1,20 +1,29 @@
-import { DeepPartial, MockCloudEventPartials } from '../../types';
+import { DeepPartial, MockCloudEventAbstractFactory } from '../../types';
 import { CloudFunction } from 'firebase-functions/v2';
-import { APP_ID, getEventType, PROJECT_ID } from '../helpers';
+import {
+  APP_ID,
+  getBaseCloudEvent,
+  getEventType,
+  PROJECT_ID,
+} from '../helpers';
 import { FirebaseAlertData, AlertEvent } from 'firebase-functions/v2/alerts';
 
-export const alertsOnAlertPublished: MockCloudEventPartials<AlertEvent<
+export const alertsOnAlertPublished: MockCloudEventAbstractFactory<AlertEvent<
   FirebaseAlertData
 >> = {
-  generatePartial(
-    _: CloudFunction<AlertEvent<FirebaseAlertData>>
-  ): DeepPartial<AlertEvent<FirebaseAlertData>> {
+  generateMock(
+    cloudFunction: CloudFunction<AlertEvent<FirebaseAlertData>>
+  ): AlertEvent<FirebaseAlertData> {
     const source = `//firebasealerts.googleapis.com/projects/${PROJECT_ID}`;
 
     const alertType = 'appDistribution.newTesterIosDevice';
     const appId = APP_ID;
 
     return {
+      // Spread common fields
+      ...getBaseCloudEvent(cloudFunction),
+      // Spread fields specific to this CloudEvent
+
       alertType,
       appId,
       data: getOnAlertPublishedData(),
diff --git a/src/cloudevent/partials/alerts/app-distribution-on-new-tester-ios-device-published.ts b/src/cloudevent/mocks/alerts/app-distribution-on-new-tester-ios-device-published.ts
similarity index 70%
rename from src/cloudevent/partials/alerts/app-distribution-on-new-tester-ios-device-published.ts
rename to src/cloudevent/mocks/alerts/app-distribution-on-new-tester-ios-device-published.ts
index 4d8a22d..25581e1 100644
--- a/src/cloudevent/partials/alerts/app-distribution-on-new-tester-ios-device-published.ts
+++ b/src/cloudevent/mocks/alerts/app-distribution-on-new-tester-ios-device-published.ts
@@ -1,21 +1,29 @@
-import { DeepPartial, MockCloudEventPartials } from '../../types';
+import { DeepPartial, MockCloudEventAbstractFactory } from '../../types';
 import { CloudFunction } from 'firebase-functions/v2';
-import { getEventFilters, getEventType, PROJECT_ID } from '../helpers';
+import {
+  getBaseCloudEvent,
+  getEventFilters,
+  getEventType,
+  PROJECT_ID,
+} from '../helpers';
 import {
   AppDistributionEvent,
   NewTesterDevicePayload,
 } from 'firebase-functions/v2/alerts/appDistribution';
 
-export const alertsAppDistributionOnNewTesterIosDevicePublished: MockCloudEventPartials<AppDistributionEvent<
+export const alertsAppDistributionOnNewTesterIosDevicePublished: MockCloudEventAbstractFactory<AppDistributionEvent<
   NewTesterDevicePayload
 >> = {
-  generatePartial(
-    _: CloudFunction<AppDistributionEvent<NewTesterDevicePayload>>
-  ): DeepPartial<AppDistributionEvent<NewTesterDevicePayload>> {
+  generateMock(
+    cloudFunction: CloudFunction<AppDistributionEvent<NewTesterDevicePayload>>
+  ): AppDistributionEvent<NewTesterDevicePayload> {
     const source = `//firebasealerts.googleapis.com/projects/${PROJECT_ID}`;
     const now = new Date().toISOString();
 
     return {
+      // Spread common fields
+      ...getBaseCloudEvent(cloudFunction),
+      // Spread fields specific to this CloudEvent
       source,
       data: {
         createTime: now,
diff --git a/src/cloudevent/partials/alerts/billing-on-plan-automated-update-published.ts b/src/cloudevent/mocks/alerts/billing-on-plan-automated-update-published.ts
similarity index 71%
rename from src/cloudevent/partials/alerts/billing-on-plan-automated-update-published.ts
rename to src/cloudevent/mocks/alerts/billing-on-plan-automated-update-published.ts
index 2468094..67d7eee 100644
--- a/src/cloudevent/partials/alerts/billing-on-plan-automated-update-published.ts
+++ b/src/cloudevent/mocks/alerts/billing-on-plan-automated-update-published.ts
@@ -1,21 +1,29 @@
-import { DeepPartial, MockCloudEventPartials } from '../../types';
+import { DeepPartial, MockCloudEventAbstractFactory } from '../../types';
 import { CloudFunction } from 'firebase-functions/v2';
 import { FirebaseAlertData } from 'firebase-functions/v2/alerts';
 import {
   BillingEvent,
   PlanAutomatedUpdatePayload,
 } from 'firebase-functions/v2/alerts/billing';
-import { getEventFilters, getEventType, PROJECT_ID } from '../helpers';
+import {
+  getBaseCloudEvent,
+  getEventFilters,
+  getEventType,
+  PROJECT_ID,
+} from '../helpers';
 
-export const alertsBillingOnPlanAutomatedUpdatePublished: MockCloudEventPartials<BillingEvent<
+export const alertsBillingOnPlanAutomatedUpdatePublished: MockCloudEventAbstractFactory<BillingEvent<
   PlanAutomatedUpdatePayload
 >> = {
-  generatePartial(
-    _: CloudFunction<BillingEvent<PlanAutomatedUpdatePayload>>
-  ): DeepPartial<BillingEvent<PlanAutomatedUpdatePayload>> {
+  generateMock(
+    cloudFunction: CloudFunction<BillingEvent<PlanAutomatedUpdatePayload>>
+  ): BillingEvent<PlanAutomatedUpdatePayload> {
     const source = `//firebasealerts.googleapis.com/projects/${PROJECT_ID}`;
 
     return {
+      // Spread common fields
+      ...getBaseCloudEvent(cloudFunction),
+      // Spread fields specific to this CloudEvent
       source,
       data: getBillingPlanAutomatedUpdateData(),
     };
diff --git a/src/cloudevent/partials/alerts/billing-on-plan-update-published.ts b/src/cloudevent/mocks/alerts/billing-on-plan-update-published.ts
similarity index 68%
rename from src/cloudevent/partials/alerts/billing-on-plan-update-published.ts
rename to src/cloudevent/mocks/alerts/billing-on-plan-update-published.ts
index b3d4f4d..90efd90 100644
--- a/src/cloudevent/partials/alerts/billing-on-plan-update-published.ts
+++ b/src/cloudevent/mocks/alerts/billing-on-plan-update-published.ts
@@ -1,21 +1,29 @@
-import { DeepPartial, MockCloudEventPartials } from '../../types';
+import { DeepPartial, MockCloudEventAbstractFactory } from '../../types';
 import { CloudFunction } from 'firebase-functions/v2';
 import { FirebaseAlertData } from 'firebase-functions/v2/alerts';
 import {
   BillingEvent,
   PlanUpdatePayload,
 } from 'firebase-functions/v2/alerts/billing';
-import { getEventFilters, getEventType, PROJECT_ID } from '../helpers';
+import {
+  getBaseCloudEvent,
+  getEventFilters,
+  getEventType,
+  PROJECT_ID,
+} from '../helpers';
 
-export const alertsBillingOnPlanUpdatePublished: MockCloudEventPartials<BillingEvent<
+export const alertsBillingOnPlanUpdatePublished: MockCloudEventAbstractFactory<BillingEvent<
   PlanUpdatePayload
 >> = {
-  generatePartial(
-    _: CloudFunction<BillingEvent<PlanUpdatePayload>>
-  ): DeepPartial<BillingEvent<PlanUpdatePayload>> {
+  generateMock(
+    cloudFunction: CloudFunction<BillingEvent<PlanUpdatePayload>>
+  ): BillingEvent<PlanUpdatePayload> {
     const source = `//firebasealerts.googleapis.com/projects/${PROJECT_ID}`;
 
     return {
+      // Spread common fields
+      ...getBaseCloudEvent(cloudFunction),
+      // Spread fields specific to this CloudEvent
       source,
       data: getBillingPlanUpdateData(),
     };
diff --git a/src/cloudevent/partials/alerts/crashlytics-on-new-anr-issue-published.ts b/src/cloudevent/mocks/alerts/crashlytics-on-new-anr-issue-published.ts
similarity index 73%
rename from src/cloudevent/partials/alerts/crashlytics-on-new-anr-issue-published.ts
rename to src/cloudevent/mocks/alerts/crashlytics-on-new-anr-issue-published.ts
index b3764cb..1a465a6 100644
--- a/src/cloudevent/partials/alerts/crashlytics-on-new-anr-issue-published.ts
+++ b/src/cloudevent/mocks/alerts/crashlytics-on-new-anr-issue-published.ts
@@ -1,21 +1,29 @@
-import { DeepPartial, MockCloudEventPartials } from '../../types';
+import { DeepPartial, MockCloudEventAbstractFactory } from '../../types';
 import { CloudFunction } from 'firebase-functions/v2';
-import { getEventFilters, getEventType, PROJECT_ID } from '../helpers';
+import {
+  getBaseCloudEvent,
+  getEventFilters,
+  getEventType,
+  PROJECT_ID,
+} from '../helpers';
 import {
   CrashlyticsEvent,
   NewAnrIssuePayload,
 } from 'firebase-functions/v2/alerts/crashlytics';
 import { FirebaseAlertData } from 'firebase-functions/v2/alerts';
 
-export const alertsCrashlyticsOnNewAnrIssuePublished: MockCloudEventPartials<CrashlyticsEvent<
+export const alertsCrashlyticsOnNewAnrIssuePublished: MockCloudEventAbstractFactory<CrashlyticsEvent<
   NewAnrIssuePayload
 >> = {
-  generatePartial(
-    _: CloudFunction<CrashlyticsEvent<NewAnrIssuePayload>>
-  ): DeepPartial<CrashlyticsEvent<NewAnrIssuePayload>> {
+  generateMock(
+    cloudFunction: CloudFunction<CrashlyticsEvent<NewAnrIssuePayload>>
+  ): CrashlyticsEvent<NewAnrIssuePayload> {
     const source = `//firebasealerts.googleapis.com/projects/${PROJECT_ID}`;
 
     return {
+      // Spread common fields
+      ...getBaseCloudEvent(cloudFunction),
+      // Spread fields specific to this CloudEvent
       source,
       data: getCrashlyticsNewAnrIssueData(),
     };
diff --git a/src/cloudevent/partials/alerts/crashlytics-on-new-fatal-issue-published.ts b/src/cloudevent/mocks/alerts/crashlytics-on-new-fatal-issue-published.ts
similarity index 73%
rename from src/cloudevent/partials/alerts/crashlytics-on-new-fatal-issue-published.ts
rename to src/cloudevent/mocks/alerts/crashlytics-on-new-fatal-issue-published.ts
index 34ae135..7cb8126 100644
--- a/src/cloudevent/partials/alerts/crashlytics-on-new-fatal-issue-published.ts
+++ b/src/cloudevent/mocks/alerts/crashlytics-on-new-fatal-issue-published.ts
@@ -1,21 +1,29 @@
-import { DeepPartial, MockCloudEventPartials } from '../../types';
+import { DeepPartial, MockCloudEventAbstractFactory } from '../../types';
 import { CloudFunction } from 'firebase-functions/v2';
-import { getEventFilters, getEventType, PROJECT_ID } from '../helpers';
+import {
+  getBaseCloudEvent,
+  getEventFilters,
+  getEventType,
+  PROJECT_ID,
+} from '../helpers';
 import {
   CrashlyticsEvent,
   NewFatalIssuePayload,
 } from 'firebase-functions/v2/alerts/crashlytics';
 import { FirebaseAlertData } from 'firebase-functions/v2/alerts';
 
-export const alertsCrashlyticsOnNewFatalIssuePublished: MockCloudEventPartials<CrashlyticsEvent<
+export const alertsCrashlyticsOnNewFatalIssuePublished: MockCloudEventAbstractFactory<CrashlyticsEvent<
   NewFatalIssuePayload
 >> = {
-  generatePartial(
-    _: CloudFunction<CrashlyticsEvent<NewFatalIssuePayload>>
-  ): DeepPartial<CrashlyticsEvent<NewFatalIssuePayload>> {
+  generateMock(
+    cloudFunction: CloudFunction<CrashlyticsEvent<NewFatalIssuePayload>>
+  ): CrashlyticsEvent<NewFatalIssuePayload> {
     const source = `//firebasealerts.googleapis.com/projects/${PROJECT_ID}`;
 
     return {
+      // Spread common fields
+      ...getBaseCloudEvent(cloudFunction),
+      // Spread fields specific to this CloudEvent
       source,
       data: getCrashlyticsNewFatalIssueData(),
     };
diff --git a/src/cloudevent/partials/alerts/crashlytics-on-new-nonfatal-issue-published.ts b/src/cloudevent/mocks/alerts/crashlytics-on-new-nonfatal-issue-published.ts
similarity index 73%
rename from src/cloudevent/partials/alerts/crashlytics-on-new-nonfatal-issue-published.ts
rename to src/cloudevent/mocks/alerts/crashlytics-on-new-nonfatal-issue-published.ts
index 73b6c09..85a1c5c 100644
--- a/src/cloudevent/partials/alerts/crashlytics-on-new-nonfatal-issue-published.ts
+++ b/src/cloudevent/mocks/alerts/crashlytics-on-new-nonfatal-issue-published.ts
@@ -1,21 +1,29 @@
-import { DeepPartial, MockCloudEventPartials } from '../../types';
+import { DeepPartial, MockCloudEventAbstractFactory } from '../../types';
 import { CloudFunction } from 'firebase-functions/v2';
-import { getEventFilters, getEventType, PROJECT_ID } from '../helpers';
+import {
+  getBaseCloudEvent,
+  getEventFilters,
+  getEventType,
+  PROJECT_ID,
+} from '../helpers';
 import {
   CrashlyticsEvent,
   NewNonfatalIssuePayload,
 } from 'firebase-functions/v2/alerts/crashlytics';
 import { FirebaseAlertData } from 'firebase-functions/v2/alerts';
 
-export const alertsCrashlyticsOnNewNonfatalIssuePublished: MockCloudEventPartials<CrashlyticsEvent<
+export const alertsCrashlyticsOnNewNonfatalIssuePublished: MockCloudEventAbstractFactory<CrashlyticsEvent<
   NewNonfatalIssuePayload
 >> = {
-  generatePartial(
-    _: CloudFunction<CrashlyticsEvent<NewNonfatalIssuePayload>>
-  ): DeepPartial<CrashlyticsEvent<NewNonfatalIssuePayload>> {
+  generateMock(
+    cloudFunction: CloudFunction<CrashlyticsEvent<NewNonfatalIssuePayload>>
+  ): CrashlyticsEvent<NewNonfatalIssuePayload> {
     const source = `//firebasealerts.googleapis.com/projects/${PROJECT_ID}`;
 
     return {
+      // Spread common fields
+      ...getBaseCloudEvent(cloudFunction),
+      // Spread fields specific to this CloudEvent
       source,
       data: getCrashlyticsNewNonfatalIssueData(),
     };
diff --git a/src/cloudevent/partials/alerts/crashlytics-on-regression-alert-published.ts b/src/cloudevent/mocks/alerts/crashlytics-on-regression-alert-published.ts
similarity index 74%
rename from src/cloudevent/partials/alerts/crashlytics-on-regression-alert-published.ts
rename to src/cloudevent/mocks/alerts/crashlytics-on-regression-alert-published.ts
index 1b1fe23..a23c351 100644
--- a/src/cloudevent/partials/alerts/crashlytics-on-regression-alert-published.ts
+++ b/src/cloudevent/mocks/alerts/crashlytics-on-regression-alert-published.ts
@@ -1,21 +1,29 @@
-import { DeepPartial, MockCloudEventPartials } from '../../types';
+import { DeepPartial, MockCloudEventAbstractFactory } from '../../types';
 import { CloudFunction } from 'firebase-functions/v2';
-import { getEventFilters, getEventType, PROJECT_ID } from '../helpers';
+import {
+  getBaseCloudEvent,
+  getEventFilters,
+  getEventType,
+  PROJECT_ID,
+} from '../helpers';
 import {
   CrashlyticsEvent,
   RegressionAlertPayload,
 } from 'firebase-functions/v2/alerts/crashlytics';
 import { FirebaseAlertData } from 'firebase-functions/v2/alerts';
 
-export const alertsCrashlyticsOnRegressionAlertPublished: MockCloudEventPartials<CrashlyticsEvent<
+export const alertsCrashlyticsOnRegressionAlertPublished: MockCloudEventAbstractFactory<CrashlyticsEvent<
   RegressionAlertPayload
 >> = {
-  generatePartial(
-    _: CloudFunction<CrashlyticsEvent<RegressionAlertPayload>>
-  ): DeepPartial<CrashlyticsEvent<RegressionAlertPayload>> {
+  generateMock(
+    cloudFunction: CloudFunction<CrashlyticsEvent<RegressionAlertPayload>>
+  ): CrashlyticsEvent<RegressionAlertPayload> {
     const source = `//firebasealerts.googleapis.com/projects/${PROJECT_ID}`;
 
     return {
+      // Spread common fields
+      ...getBaseCloudEvent(cloudFunction),
+      // Spread fields specific to this CloudEvent
       source,
       data: getCrashlyticsRegressionAlertPayload(),
     };
diff --git a/src/cloudevent/partials/alerts/crashlytics-on-stability-digest-published.ts b/src/cloudevent/mocks/alerts/crashlytics-on-stability-digest-published.ts
similarity index 76%
rename from src/cloudevent/partials/alerts/crashlytics-on-stability-digest-published.ts
rename to src/cloudevent/mocks/alerts/crashlytics-on-stability-digest-published.ts
index 7459ac0..3b22992 100644
--- a/src/cloudevent/partials/alerts/crashlytics-on-stability-digest-published.ts
+++ b/src/cloudevent/mocks/alerts/crashlytics-on-stability-digest-published.ts
@@ -1,21 +1,29 @@
-import { DeepPartial, MockCloudEventPartials } from '../../types';
+import { DeepPartial, MockCloudEventAbstractFactory } from '../../types';
 import { CloudFunction } from 'firebase-functions/v2';
-import { getEventFilters, getEventType, PROJECT_ID } from '../helpers';
+import {
+  getBaseCloudEvent,
+  getEventFilters,
+  getEventType,
+  PROJECT_ID,
+} from '../helpers';
 import {
   CrashlyticsEvent,
   StabilityDigestPayload,
 } from 'firebase-functions/v2/alerts/crashlytics';
 import { FirebaseAlertData } from 'firebase-functions/v2/alerts';
 
-export const alertsCrashlyticsOnStabilityDigestPublished: MockCloudEventPartials<CrashlyticsEvent<
+export const alertsCrashlyticsOnStabilityDigestPublished: MockCloudEventAbstractFactory<CrashlyticsEvent<
   StabilityDigestPayload
 >> = {
-  generatePartial(
-    _: CloudFunction<CrashlyticsEvent<StabilityDigestPayload>>
-  ): DeepPartial<CrashlyticsEvent<StabilityDigestPayload>> {
+  generateMock(
+    cloudFunction: CloudFunction<CrashlyticsEvent<StabilityDigestPayload>>
+  ): CrashlyticsEvent<StabilityDigestPayload> {
     const source = `//firebasealerts.googleapis.com/projects/${PROJECT_ID}`;
 
     return {
+      // Spread common fields
+      ...getBaseCloudEvent(cloudFunction),
+      // Spread fields specific to this CloudEvent
       source,
       data: getCrashlyticsStabilityData(),
     };
diff --git a/src/cloudevent/partials/alerts/crashlytics-on-velocity-alert-published.ts b/src/cloudevent/mocks/alerts/crashlytics-on-velocity-alert-published.ts
similarity index 75%
rename from src/cloudevent/partials/alerts/crashlytics-on-velocity-alert-published.ts
rename to src/cloudevent/mocks/alerts/crashlytics-on-velocity-alert-published.ts
index af96e13..386e9cc 100644
--- a/src/cloudevent/partials/alerts/crashlytics-on-velocity-alert-published.ts
+++ b/src/cloudevent/mocks/alerts/crashlytics-on-velocity-alert-published.ts
@@ -1,21 +1,29 @@
-import { DeepPartial, MockCloudEventPartials } from '../../types';
+import { DeepPartial, MockCloudEventAbstractFactory } from '../../types';
 import { CloudFunction } from 'firebase-functions/v2';
-import { getEventFilters, getEventType, PROJECT_ID } from '../helpers';
+import {
+  getBaseCloudEvent,
+  getEventFilters,
+  getEventType,
+  PROJECT_ID,
+} from '../helpers';
 import {
   CrashlyticsEvent,
   VelocityAlertPayload,
 } from 'firebase-functions/v2/alerts/crashlytics';
 import { FirebaseAlertData } from 'firebase-functions/v2/alerts';
 
-export const alertsCrashlyticsOnVelocityAlertPublished: MockCloudEventPartials<CrashlyticsEvent<
+export const alertsCrashlyticsOnVelocityAlertPublished: MockCloudEventAbstractFactory<CrashlyticsEvent<
   VelocityAlertPayload
 >> = {
-  generatePartial(
-    _: CloudFunction<CrashlyticsEvent<VelocityAlertPayload>>
-  ): DeepPartial<CrashlyticsEvent<VelocityAlertPayload>> {
+  generateMock(
+    cloudFunction: CloudFunction<CrashlyticsEvent<VelocityAlertPayload>>
+  ): CrashlyticsEvent<VelocityAlertPayload> {
     const source = `//firebasealerts.googleapis.com/projects/${PROJECT_ID}`;
 
     return {
+      // Spread common fields
+      ...getBaseCloudEvent(cloudFunction),
+      // Spread fields specific to this CloudEvent
       source,
       data: getCrashlyticsVelocityAlertData(),
     };
diff --git a/src/cloudevent/mocks/eventarc/eventarc-on-custom-event-published.ts b/src/cloudevent/mocks/eventarc/eventarc-on-custom-event-published.ts
new file mode 100644
index 0000000..7043875
--- /dev/null
+++ b/src/cloudevent/mocks/eventarc/eventarc-on-custom-event-published.ts
@@ -0,0 +1,25 @@
+import { DeepPartial, MockCloudEventAbstractFactory } from '../../types';
+import { CloudEvent, CloudFunction } from 'firebase-functions/v2';
+import { getBaseCloudEvent } from '../helpers';
+
+export const eventarcOnCustomEventPublished: MockCloudEventAbstractFactory<any> = {
+  generateMock(
+    cloudFunction: CloudFunction<CloudEvent<any>>,
+    cloudEventPartial?: DeepPartial<CloudEvent<any>>
+  ): CloudEvent<any> {
+    const source = 'eventarc_source';
+    const subject = 'eventarc_subject';
+
+    return {
+      // Spread common fields
+      ...getBaseCloudEvent(cloudFunction),
+      // Spread fields specific to this CloudEvent
+      data: cloudEventPartial?.data || {},
+      source,
+      subject,
+    };
+  },
+  match(_: CloudFunction<CloudEvent<unknown>>): boolean {
+    return true;
+  },
+};
diff --git a/src/cloudevent/mocks/helpers.ts b/src/cloudevent/mocks/helpers.ts
new file mode 100644
index 0000000..e0f76e4
--- /dev/null
+++ b/src/cloudevent/mocks/helpers.ts
@@ -0,0 +1,40 @@
+import { CloudEvent, CloudFunction } from 'firebase-functions/v2';
+import { DeepPartial } from '../types';
+
+export const APP_ID = '__APP_ID__';
+export const PROJECT_ID = '42';
+export const FILENAME = 'file_name';
+
+export function getEventType(cloudFunction: CloudFunction<any>): string {
+  return cloudFunction?.__endpoint?.eventTrigger?.eventType || '';
+}
+
+export function getEventFilters(
+  cloudFunction: CloudFunction<any>
+): Record<string, string> {
+  return cloudFunction?.__endpoint?.eventTrigger?.eventFilters || {};
+}
+
+export function getBaseCloudEvent<EventType extends CloudEvent<unknown>>(
+  cloudFunction: CloudFunction<EventType>
+): EventType {
+  return {
+    specversion: '1.0',
+    id: makeEventId(),
+    data: undefined,
+    source: '', // Required field that will get overridden by Provider-specific MockCloudEventPartials
+    type: getEventType(cloudFunction),
+    time: new Date().toISOString(),
+  } as EventType;
+}
+
+function makeEventId(): string {
+  return (
+    Math.random()
+      .toString(36)
+      .substring(2, 15) +
+    Math.random()
+      .toString(36)
+      .substring(2, 15)
+  );
+}
diff --git a/src/cloudevent/partials/partials.ts b/src/cloudevent/mocks/partials.ts
similarity index 96%
rename from src/cloudevent/partials/partials.ts
rename to src/cloudevent/mocks/partials.ts
index 0f5e6ce..116c9d5 100644
--- a/src/cloudevent/partials/partials.ts
+++ b/src/cloudevent/mocks/partials.ts
@@ -1,4 +1,4 @@
-import { MockCloudEventPartials } from '../types';
+import { MockCloudEventAbstractFactory } from '../types';
 import { alertsOnAlertPublished } from './alerts/alerts-on-alert-published';
 import { alertsCrashlyticsOnNewAnrIssuePublished } from './alerts/crashlytics-on-new-anr-issue-published';
 import { alertsCrashlyticsOnNewFatalIssuePublished } from './alerts/crashlytics-on-new-fatal-issue-published';
@@ -18,7 +18,7 @@ import { storageV1 } from './storage';
  * (eg {@link alertsOnAlertPublished}). In addition,
  * {@link eventarcOnCustomEventPublished} acts as a catch-all.
  */
-export const LIST_OF_MOCK_CLOUD_EVENT_PARTIALS: Array<MockCloudEventPartials<
+export const LIST_OF_MOCK_CLOUD_EVENT_PARTIALS: Array<MockCloudEventAbstractFactory<
   any
 >> = [
   alertsCrashlyticsOnNewAnrIssuePublished,
diff --git a/src/cloudevent/mocks/pubsub/pubsub-on-message-published.ts b/src/cloudevent/mocks/pubsub/pubsub-on-message-published.ts
new file mode 100644
index 0000000..78a0af7
--- /dev/null
+++ b/src/cloudevent/mocks/pubsub/pubsub-on-message-published.ts
@@ -0,0 +1,67 @@
+import { DeepPartial, MockCloudEventAbstractFactory } from '../../types';
+import { CloudEvent, CloudFunction, pubsub } from 'firebase-functions/v2';
+import {
+  getBaseCloudEvent,
+  getEventFilters,
+  getEventType,
+  PROJECT_ID,
+} from '../helpers';
+
+export const pubsubOnMessagePublished: MockCloudEventAbstractFactory<CloudEvent<
+  pubsub.MessagePublishedData
+>> = {
+  generateMock(
+    cloudFunction: CloudFunction<CloudEvent<pubsub.MessagePublishedData>>,
+    cloudEventPartial?: DeepPartial<CloudEvent<pubsub.MessagePublishedData>>
+  ): CloudEvent<pubsub.MessagePublishedData> {
+    const topicId = getEventFilters(cloudFunction)?.topic || '';
+    const source = `//pubsub.googleapis.com/projects/${PROJECT_ID}/topics/${topicId}`;
+    const subscription = `projects/${PROJECT_ID}/subscriptions/pubsubexample-1`;
+
+    // Used if no data.message.json is provided by the partial;
+    const dataMessageJsonDefault = { hello: 'world' };
+    const dataMessageAttributesDefault = {
+      'sample-attribute': 'I am an attribute',
+    };
+
+    const dataMessageJson =
+      cloudEventPartial?.data?.message?.json || dataMessageJsonDefault;
+
+    // We should respect if the user provides their own message.data.
+    const dataMessageData =
+      cloudEventPartial?.data?.message?.data ||
+      Buffer.from(JSON.stringify(dataMessageJson)).toString('base64');
+
+    // TODO - consider warning the user if their data does not match the json they provide
+
+    const messageData = {
+      data: dataMessageData,
+      messageId: cloudEventPartial?.data?.message?.messageId || 'message_id',
+      attributes:
+        cloudEventPartial?.data?.message?.attributes ||
+        dataMessageAttributesDefault,
+    };
+    const message = new pubsub.Message(messageData);
+
+    return {
+      // Spread common fields
+      ...getBaseCloudEvent(cloudFunction),
+      // Spread fields specific to this CloudEvent
+      source,
+      data: {
+        /**
+         * Note: Its very important we return the JSON representation of the message here. Without it,
+         * ts-merge blows away `data.message`.
+         */
+        message: message.toJSON(),
+        subscription,
+      },
+    };
+  },
+  match(cloudFunction: CloudFunction<CloudEvent<unknown>>): boolean {
+    return (
+      getEventType(cloudFunction) ===
+      'google.cloud.pubsub.topic.v1.messagePublished'
+    );
+  },
+};
diff --git a/src/cloudevent/mocks/storage/index.ts b/src/cloudevent/mocks/storage/index.ts
new file mode 100644
index 0000000..bf2e221
--- /dev/null
+++ b/src/cloudevent/mocks/storage/index.ts
@@ -0,0 +1,42 @@
+import { DeepPartial, MockCloudEventAbstractFactory } from '../../types';
+import { CloudFunction, CloudEvent } from 'firebase-functions/v2';
+import { StorageEvent } from 'firebase-functions/v2/storage';
+import {
+  FILENAME,
+  getBaseCloudEvent,
+  getEventFilters,
+  getEventType,
+} from '../helpers';
+import { getStorageObjectData } from './storage-data';
+import { pubsub } from 'firebase-functions/lib/v2';
+
+export const storageV1: MockCloudEventAbstractFactory<StorageEvent> = {
+  generateMock(
+    cloudFunction: CloudFunction<StorageEvent>,
+    cloudEventPartial?: DeepPartial<StorageEvent>
+  ): StorageEvent {
+    const bucket =
+      cloudEventPartial?.bucket ||
+      getEventFilters(cloudFunction)?.bucket ||
+      'bucket_name';
+    const source =
+      cloudEventPartial?.source ||
+      `//storage.googleapis.com/projects/_/buckets/${bucket}`;
+    const subject = cloudEventPartial?.subject || `objects/${FILENAME}`;
+
+    return {
+      // Spread common fields
+      ...getBaseCloudEvent(cloudFunction),
+      // Spread fields specific to this CloudEvent
+      bucket,
+      source,
+      subject,
+      data: getStorageObjectData(bucket, FILENAME, 1),
+    };
+  },
+  match(cloudFunction: CloudFunction<CloudEvent<unknown>>): boolean {
+    return getEventType(cloudFunction).startsWith(
+      'google.cloud.storage.object.v1'
+    );
+  },
+};
diff --git a/src/cloudevent/partials/storage/storage-data.ts b/src/cloudevent/mocks/storage/storage-data.ts
similarity index 100%
rename from src/cloudevent/partials/storage/storage-data.ts
rename to src/cloudevent/mocks/storage/storage-data.ts
diff --git a/src/cloudevent/partials/eventarc/eventarc-on-custom-event-published.ts b/src/cloudevent/partials/eventarc/eventarc-on-custom-event-published.ts
deleted file mode 100644
index 7c55bb3..0000000
--- a/src/cloudevent/partials/eventarc/eventarc-on-custom-event-published.ts
+++ /dev/null
@@ -1,20 +0,0 @@
-import { DeepPartial, MockCloudEventPartials } from '../../types';
-import { CloudEvent, CloudFunction } from 'firebase-functions/v2';
-
-export const eventarcOnCustomEventPublished: MockCloudEventPartials<any> = {
-  generatePartial(
-    _: CloudFunction<CloudEvent<any>>
-  ): DeepPartial<CloudEvent<any>> {
-    const source = 'eventarc_source';
-    const subject = 'eventarc_subject';
-
-    return {
-      data: {},
-      source,
-      subject,
-    };
-  },
-  match(_: CloudFunction<CloudEvent<unknown>>): boolean {
-    return true;
-  },
-};
diff --git a/src/cloudevent/partials/helpers.ts b/src/cloudevent/partials/helpers.ts
deleted file mode 100644
index 19f61fb..0000000
--- a/src/cloudevent/partials/helpers.ts
+++ /dev/null
@@ -1,15 +0,0 @@
-import { CloudEvent, CloudFunction } from 'firebase-functions/v2';
-
-export const APP_ID = '__APP_ID__';
-export const PROJECT_ID = '42';
-export const FILENAME = 'file_name';
-
-export function getEventType(cloudFunction: CloudFunction<any>): string {
-  return cloudFunction?.__endpoint?.eventTrigger?.eventType || '';
-}
-
-export function getEventFilters(
-  cloudFunction: CloudFunction<any>
-): Record<string, string> {
-  return cloudFunction?.__endpoint?.eventTrigger?.eventFilters || {};
-}
diff --git a/src/cloudevent/partials/pubsub/pubsub-on-message-published.ts b/src/cloudevent/partials/pubsub/pubsub-on-message-published.ts
deleted file mode 100644
index cbb0bbe..0000000
--- a/src/cloudevent/partials/pubsub/pubsub-on-message-published.ts
+++ /dev/null
@@ -1,40 +0,0 @@
-import { DeepPartial, MockCloudEventPartials } from '../../types';
-import { CloudEvent, CloudFunction, pubsub } from 'firebase-functions/v2';
-import { getEventFilters, getEventType, PROJECT_ID } from '../helpers';
-
-export const pubsubOnMessagePublished: MockCloudEventPartials<CloudEvent<
-  pubsub.MessagePublishedData
->> = {
-  generatePartial(
-    cloudFunction: CloudFunction<CloudEvent<pubsub.MessagePublishedData>>
-  ): DeepPartial<CloudEvent<pubsub.MessagePublishedData>> {
-    const topicId = getEventFilters(cloudFunction)?.topic || '';
-    const source = `//pubsub.googleapis.com/projects/${PROJECT_ID}/topics/${topicId}`;
-    const subscription = `projects/${PROJECT_ID}/subscriptions/pubsubexample-1`;
-
-    /**
-     *  Node: The following is a Base64 string generated by the following:
-     *  Buffer.from(dataMessageJson).toString('base64')
-     */
-    const dataMessageData = 'eyJoZWxsbyI6IndvcmxkIn0=';
-
-    return {
-      source,
-      data: {
-        message: {
-          attributes: { 'sample-attribute': 'I am an attribute' },
-          data: dataMessageData, // Buffer base64 encoded
-          messageId: 'messageId',
-          publishTime: new Date().toISOString(),
-        },
-        subscription,
-      },
-    };
-  },
-  match(cloudFunction: CloudFunction<CloudEvent<unknown>>): boolean {
-    return (
-      getEventType(cloudFunction) ===
-      'google.cloud.pubsub.topic.v1.messagePublished'
-    );
-  },
-};
diff --git a/src/cloudevent/partials/storage/index.ts b/src/cloudevent/partials/storage/index.ts
deleted file mode 100644
index 301d6ff..0000000
--- a/src/cloudevent/partials/storage/index.ts
+++ /dev/null
@@ -1,27 +0,0 @@
-import { DeepPartial, MockCloudEventPartials } from '../../types';
-import { CloudFunction, CloudEvent } from 'firebase-functions/v2';
-import { StorageEvent } from 'firebase-functions/v2/storage';
-import { FILENAME, getEventFilters, getEventType } from '../helpers';
-import { getStorageObjectData } from './storage-data';
-
-export const storageV1: MockCloudEventPartials<StorageEvent> = {
-  generatePartial(
-    cloudFunction: CloudFunction<StorageEvent>
-  ): DeepPartial<StorageEvent> {
-    const bucket = getEventFilters(cloudFunction)?.bucket || 'bucket_name';
-    const source = `//storage.googleapis.com/projects/_/buckets/${bucket}`;
-    const subject = `objects/${FILENAME}`;
-
-    return {
-      bucket,
-      source,
-      subject,
-      data: getStorageObjectData(bucket, FILENAME, 1),
-    };
-  },
-  match(cloudFunction: CloudFunction<CloudEvent<unknown>>): boolean {
-    return getEventType(cloudFunction).startsWith(
-      'google.cloud.storage.object.v1'
-    );
-  },
-};
diff --git a/src/cloudevent/types.ts b/src/cloudevent/types.ts
index 4ae593c..ab51ad5 100644
--- a/src/cloudevent/types.ts
+++ b/src/cloudevent/types.ts
@@ -3,14 +3,17 @@ import { CloudEvent, CloudFunction } from 'firebase-functions/v2';
 export type DeepPartial<T extends object> = {
   [Key in keyof T]?: T[Key] extends object ? DeepPartial<T[Key]> : T[Key];
 };
-type MockCloudEventPartialFunction<EventType extends CloudEvent<unknown>> = (
-  cloudFunction: CloudFunction<EventType>
-) => DeepPartial<EventType>;
+type MockCloudEventFunction<EventType extends CloudEvent<unknown>> = (
+  cloudFunction: CloudFunction<EventType>,
+  cloudEventPartial?: DeepPartial<EventType>
+) => EventType;
 type MockCloudEventMatchFunction<EventType extends CloudEvent<unknown>> = (
   cloudFunction: CloudFunction<EventType>
 ) => boolean;
 
-export interface MockCloudEventPartials<EventType extends CloudEvent<unknown>> {
-  generatePartial: MockCloudEventPartialFunction<EventType>;
+export interface MockCloudEventAbstractFactory<
+  EventType extends CloudEvent<unknown>
+> {
+  generateMock: MockCloudEventFunction<EventType>;
   match: MockCloudEventMatchFunction<EventType>;
 }