diff --git a/packages/mock/src/MockStore.ts b/packages/mock/src/MockStore.ts
index ae64302e912..5566fd70dd0 100644
--- a/packages/mock/src/MockStore.ts
+++ b/packages/mock/src/MockStore.ts
@@ -192,12 +192,12 @@ export class MockStore implements IMockStore {
 
   filter(key: string, predicate: (val: Entity) => boolean) {
     const entity = this.store[key];
-    return Object.values(entity).filter(predicate);
+    return entity ? Object.values(entity).filter(predicate) : [];
   }
 
   find(key: string, predicate: (val: Entity) => boolean) {
     const entity = this.store[key];
-    return Object.values(entity).find(predicate);
+    return entity ? Object.values(entity).find(predicate) : undefined;
   }
 
   private getImpl<KeyT extends KeyTypeConstraints>(args: GetArgs<KeyT>) {
diff --git a/packages/mock/tests/store.spec.ts b/packages/mock/tests/store.spec.ts
index 32488ffa0ff..e1a4f6190f1 100644
--- a/packages/mock/tests/store.spec.ts
+++ b/packages/mock/tests/store.spec.ts
@@ -1,7 +1,7 @@
-import { buildSchema } from 'graphql';
-import { createMockStore } from '../src/index.js';
-import { assertIsRef, Ref } from '../src/types.js';
-import { makeRef } from '../src/utils.js';
+import {buildSchema} from 'graphql';
+import {createMockStore, MockStore} from '../src/index.js';
+import {assertIsRef, Ref} from '../src/types.js';
+import {makeRef} from '../src/utils.js';
 
 const typeDefs = /* GraphQL */ `
   type User {
@@ -626,4 +626,42 @@ describe('MockStore', () => {
     expect(store.get('User', '123', 'name', { format: 'fullName' })).toEqual('Alexandre the Great');
     expect(store.get('User', '123', 'name', { format: 'shortName' })).toEqual('Alex');
   });
+
+  describe('filter method', () => {
+    it('should be able to filter an empty list', () => {
+      const store = new MockStore({schema})
+      store.set('User', 'user1', {name: 'Ross'})
+      expect(store.filter('User', () => false)).toEqual([])
+      store.reset()
+      expect(store.filter('User', () => true)).toEqual([])
+    })
+
+    it('should apply the filter', () => {
+      const store = new MockStore({schema})
+      store.set('User', 'user1', {name: 'Ross'})
+      store.set('User', 'user2', {name: 'Nico'})
+      expect(store.filter('User', () => true)).toEqual([{name: 'Ross'}, {name: 'Nico'}])
+      expect(store.filter('User', ({name}) => (name as string).startsWith('R'))).toEqual([{name: 'Ross'}])
+    })
+  })
+
+  describe('find method', () => {
+    it('should return undefined for an empty store', () => {
+      const store = new MockStore({schema})
+      expect(store.find('User', () => true)).toBeUndefined()
+    })
+
+    it('should return undefined for a miss', () => {
+      const store = new MockStore({schema})
+      store.set('User', 'user1', {name: 'Ross'})
+      expect(store.find('User', () => false)).toBeUndefined()
+    })
+
+    it('should return a match', () => {
+      const store = new MockStore({schema})
+      store.set('User', 'user1', {name: 'Ross'})
+      store.set('User', 'user2', {name: 'Nico'})
+      expect(store.find('User', ({name}) => (name as string).startsWith('N'))).toEqual({name: 'Nico'})
+    })
+  })
 });