diff --git a/lib/reducers/integrity-reducer.test.js b/lib/reducers/integrity-reducer.test.js
new file mode 100644
index 000000000..4239710f6
--- /dev/null
+++ b/lib/reducers/integrity-reducer.test.js
@@ -0,0 +1,230 @@
+// @flow
+
+import { reduceIntegrityStore } from './integrity-reducer.js';
+import { updateIntegrityStoreActionType } from '../actions/integrity-actions.js';
+import type { ThreadStoreOperation } from '../ops/thread-store-ops';
+import { type ThreadHashes } from '../types/integrity-types.js';
+import type { RawThreadInfo } from '../types/minimally-encoded-thread-permissions-types.js';
+import { hash } from '../utils/objects.js';
+
+jest.mock('../utils/config.js');
+
+const currentThreadHashes: ThreadHashes = {
+  '256|2204191': 1029852,
+  '256|2205980': 3119392,
+  '256|2208693': 4157082,
+  '256|2212631': 8951764,
+};
+
+const threadIDToUpdate = '256|2210486';
+const threadIDsToUpdateList = [threadIDToUpdate];
+
+type ThreadInfos = {
+  +[string]: RawThreadInfo,
+};
+
+const threadInfos: ThreadInfos = {
+  [threadIDToUpdate]: {
+    currentUser: {
+      role: '256|83795',
+      permissions: '3',
+      minimallyEncoded: true,
+      unread: true,
+      subscription: {
+        pushNotifs: true,
+        home: true,
+      },
+    },
+    id: threadIDToUpdate,
+    type: 12,
+    name: 'GENESIS',
+    description: '',
+    color: '648caa',
+    creationTime: 1689091732528,
+    parentThreadID: null,
+    repliesCount: 0,
+    containingThreadID: null,
+    community: null,
+    pinnedCount: 0,
+    minimallyEncoded: true,
+    members: [
+      {
+        id: '256',
+        role: '256|83796',
+        permissions: '3f73ff',
+        isSender: true,
+        minimallyEncoded: true,
+      },
+      {
+        id: '83810',
+        role: '256|83795',
+        permissions: '3',
+        isSender: false,
+        minimallyEncoded: true,
+      },
+    ],
+    roles: {
+      '256|83795': {
+        id: '256|83795',
+        name: 'Members',
+        permissions: ['000', '010', '005', '015', '0a7'],
+        minimallyEncoded: true,
+      },
+      '256|83796': {
+        id: '256|83796',
+        name: 'Admins',
+        permissions: ['000', '010', '005', '015', '0a7'],
+        minimallyEncoded: true,
+      },
+    },
+  },
+};
+
+const threadHashToUpdate = hash(threadInfos[threadIDToUpdate]);
+
+describe('reduceIntegrityStore', () => {
+  it('should update integrity store with new thread hash', () => {
+    const oldIntegrityStore = {
+      threadHashes: currentThreadHashes,
+      threadHashingStatus: 'completed',
+    };
+
+    const updateThreadHashesAction = {
+      type: updateIntegrityStoreActionType,
+      payload: { threadIDsToHash: threadIDsToUpdateList },
+    };
+
+    expect(
+      reduceIntegrityStore(
+        oldIntegrityStore,
+        updateThreadHashesAction,
+        () => null,
+        threadInfos,
+        [],
+      ).integrityStore,
+    ).toEqual({
+      threadHashes: {
+        ...currentThreadHashes,
+        [threadIDToUpdate]: threadHashToUpdate,
+      },
+      threadHashingStatus: 'completed',
+    });
+  });
+
+  it('should update integrity store with new thread hash', () => {
+    const oldIntegrityStore = {
+      threadHashes: currentThreadHashes,
+      threadHashingStatus: 'completed',
+    };
+
+    const updateThreadHashesAction = {
+      type: updateIntegrityStoreActionType,
+      payload: { threadHashingStatus: 'completed' },
+    };
+
+    const threadStoreOperations: Array<ThreadStoreOperation> = [
+      {
+        type: 'replace',
+        payload: {
+          id: threadIDToUpdate,
+          threadInfo: threadInfos[threadIDToUpdate],
+        },
+      },
+    ];
+
+    expect(
+      reduceIntegrityStore(
+        oldIntegrityStore,
+        updateThreadHashesAction,
+        () => null,
+        threadInfos,
+        threadStoreOperations,
+      ).integrityStore,
+    ).toEqual({
+      threadHashes: {
+        ...currentThreadHashes,
+        [threadIDToUpdate]: threadHashToUpdate,
+      },
+      threadHashingStatus: 'completed',
+    });
+  });
+
+  it('should remove two thread hashes', () => {
+    const oldIntegrityStore = {
+      threadHashes: currentThreadHashes,
+      threadHashingStatus: 'completed',
+    };
+
+    const thread_ids_remove = ['256|2204191', '256|2205980'];
+
+    const thread_hashes_after_removal: ThreadHashes = {
+      '256|2208693': 4157082,
+      '256|2212631': 8951764,
+    };
+
+    const updateThreadHashesAction = {
+      type: updateIntegrityStoreActionType,
+      payload: { threadHashingStatus: 'completed' },
+    };
+
+    const threadStoreOperations: Array<ThreadStoreOperation> = [
+      {
+        type: 'remove',
+        payload: {
+          ids: thread_ids_remove,
+        },
+      },
+    ];
+
+    expect(
+      reduceIntegrityStore(
+        oldIntegrityStore,
+        updateThreadHashesAction,
+        () => null,
+        threadInfos,
+        threadStoreOperations,
+      ).integrityStore,
+    ).toEqual({
+      threadHashes: thread_hashes_after_removal,
+      threadHashingStatus: 'completed',
+    });
+  });
+
+  it('should clear thread hashes and update with a single thread hash', () => {
+    const oldIntegrityStore = {
+      threadHashes: currentThreadHashes,
+      threadHashingStatus: 'completed',
+    };
+
+    const updateThreadHashesAction = {
+      type: updateIntegrityStoreActionType,
+      payload: { threadHashingStatus: 'completed' },
+    };
+
+    const threadStoreOperations: Array<ThreadStoreOperation> = [
+      {
+        type: 'remove_all',
+      },
+      {
+        type: 'replace',
+        payload: {
+          id: threadIDToUpdate,
+          threadInfo: threadInfos[threadIDToUpdate],
+        },
+      },
+    ];
+
+    expect(
+      reduceIntegrityStore(
+        oldIntegrityStore,
+        updateThreadHashesAction,
+        () => null,
+        threadInfos,
+        threadStoreOperations,
+      ).integrityStore,
+    ).toEqual({
+      threadHashes: { [threadIDToUpdate]: threadHashToUpdate },
+      threadHashingStatus: 'completed',
+    });
+  });
+});