diff --git a/src/api/createAttachedSignature.test.ts b/src/api/createAttachedSignature.test.ts
index b71d97b..582e192 100644
--- a/src/api/createAttachedSignature.test.ts
+++ b/src/api/createAttachedSignature.test.ts
@@ -49,17 +49,17 @@ window.cadesplugin.CreateObjectAsync.mockImplementation((object) => {
 
 describe('createAttachedSignature', () => {
   test('uses Buffer to encrypt the message', async () => {
-    const originalBufferFrom = (window as any).Buffer.from;
+    const originalBufferFrom = global.Buffer.from;
 
-    (window as any).Buffer.from = jest.fn(() => ({
+    (global.Buffer.from as jest.Mock) = jest.fn(() => ({
       toString: jest.fn(),
     }));
 
     await createAttachedSignature(parsedCertificateMock.thumbprint, 'message');
 
-    expect((window as any).Buffer.from).toHaveBeenCalledTimes(1);
+    expect(global.Buffer.from).toHaveBeenCalledTimes(1);
 
-    (window as any).Buffer.from = originalBufferFrom;
+    global.Buffer.from = originalBufferFrom;
   });
 
   test('uses specified certificate', async () => {
diff --git a/src/api/createHash.test.ts b/src/api/createHash.test.ts
new file mode 100644
index 0000000..baf00af
--- /dev/null
+++ b/src/api/createHash.test.ts
@@ -0,0 +1,44 @@
+import 'cadesplugin';
+import { createHash } from './createHash';
+
+const executionSteps = [Symbol('step 0'), Symbol('step 1')];
+
+const executionFlow = {
+  [executionSteps[0]]: {
+    propset_Algorithm: jest.fn(),
+    propset_DataEncoding: jest.fn(),
+    Hash: jest.fn(),
+    Value: executionSteps[1],
+  },
+  [executionSteps[1]]: 'hash',
+};
+
+window.cadesplugin.__defineExecutionFlow(executionFlow);
+window.cadesplugin.CreateObjectAsync.mockImplementation((object) => {
+  switch (object) {
+    case 'CAdESCOM.HashedData':
+      return executionSteps[0];
+  }
+});
+
+describe('createHash', () => {
+  test('uses Buffer to encrypt the message', async () => {
+    const originalBufferFrom = global.Buffer.from;
+
+    (global.Buffer.from as jest.Mock) = jest.fn(() => ({
+      toString: jest.fn(),
+    }));
+
+    await createHash('message');
+
+    expect(global.Buffer.from).toHaveBeenCalledTimes(1);
+
+    global.Buffer.from = originalBufferFrom;
+  });
+
+  test('returns created hash', async () => {
+    const hash = await createHash('message');
+
+    expect(hash).toEqual('hash');
+  });
+});