Mock the unsubscribe callback returned by onSnapshot

__tests__/full-setup-library-firestore.test.js

@@ -22,6 +22,7 @@ describe.each([
     mockBatchCreate,
     mockSettings,
     mockOnSnapShot,
+    mockQueryOnSnapshotUnsubscribe,
     mockListCollections,
     mockTimestampNow,
     mockCreate,
@@ -378,7 +379,7 @@ describe.each([
 
         await flushPromises();
 
-        expect(unsubscribe).toBeInstanceOf(Function);
+        expect(unsubscribe).toBe(mockQueryOnSnapshotUnsubscribe);
         expect(mockWhere).toHaveBeenCalled();
         expect(mockOnSnapShot).toHaveBeenCalled();
       });

__tests__/full-setup.test.js

@@ -34,6 +34,7 @@ describe.each`
     mockWithConverter,
     FakeFirestore,
     mockQueryOnSnapshot,
+    mockQueryOnSnapshotUnsubscribe,
     mockTimestampNow,
     mockRecursiveDelete,
   } = require('firestore-jest-mock/mocks/firestore');
@@ -411,7 +412,7 @@ describe.each`
 
       await flushPromises();
 
-      expect(unsubscribe).toBeInstanceOf(Function);
+      expect(unsubscribe).toBe(mockQueryOnSnapshotUnsubscribe);
       expect(mockWhere).toHaveBeenCalled();
       expect(mockOnSnapShot).not.toHaveBeenCalled();
       expect(mockQueryOnSnapshot).toHaveBeenCalled();

src/mocks/firestore.d.ts

@@ -160,6 +160,7 @@ export const mockOffset: jest.Mock;
 export const mockStartAfter: jest.Mock;
 export const mockStartAt: jest.Mock;
 export const mockQueryOnSnapshot: jest.Mock;
+export const mockQueryOnSnapshotUnsubscribe: jest.Mock;
 export const mockWithConverter: jest.Mock;
 
 // Mocks exported from Timestamp

src/mocks/query.d.ts

@@ -26,5 +26,6 @@ export const mocks: {
   mockStartAfter: jest.Mock,
   mockStartAt: jest.Mock,
   mockQueryOnSnapshot: jest.Mock,
+  mockQueryOnSnapshotUnsubscribe: jest.Mock,
   mockWithConverter: jest.Mock,
 };

src/mocks/query.js

@@ -9,6 +9,7 @@ const mockOffset = jest.fn();
 const mockStartAfter = jest.fn();
 const mockStartAt = jest.fn();
 const mockQueryOnSnapshot = jest.fn();
+const mockQueryOnSnapshotUnsubscribe = jest.fn();
 const mockWithConverter = jest.fn();
 
 class Query {
@@ -140,8 +141,8 @@ class Query {
       }
     }
 
-    // Returns an unsubscribe function
-    return () => {};
+    // Returns an unsubscribe mock
+    return mockQueryOnSnapshotUnsubscribe;
   }
 }
 
@@ -157,6 +158,7 @@ module.exports = {
     mockStartAfter,
     mockStartAt,
     mockQueryOnSnapshot,
+    mockQueryOnSnapshotUnsubscribe,
     mockWithConverter,
   },
 };