diff --git a/src/__mocks__/console-error.ts b/src/__mocks__/console-mock.ts
similarity index 73%
rename from src/__mocks__/console-error.ts
rename to src/__mocks__/console-mock.ts
index 6905734..64ee7db 100644
--- a/src/__mocks__/console-error.ts
+++ b/src/__mocks__/console-mock.ts
@@ -1,2 +1,3 @@
 // suppress logging errors to stdout while running tests
 window.console.error = jest.fn();
+window.console.warn = jest.fn();
diff --git a/src/api/createAttachedSignature.test.ts b/src/api/createAttachedSignature.test.ts
new file mode 100644
index 0000000..b71d97b
--- /dev/null
+++ b/src/api/createAttachedSignature.test.ts
@@ -0,0 +1,76 @@
+import 'cadesplugin';
+import { rawCertificates, parsedCertificates } from '../__mocks__/certificates';
+import { createAttachedSignature } from './createAttachedSignature';
+import { _getCadesCert } from '../helpers/_getCadesCert';
+
+const [rawCertificateMock] = rawCertificates;
+const [parsedCertificateMock] = parsedCertificates;
+
+jest.mock('../helpers/_getCadesCert', () => ({ _getCadesCert: jest.fn(() => rawCertificateMock) }));
+
+beforeEach(() => {
+  (_getCadesCert as jest.Mock).mockClear();
+});
+
+const executionSteps = [Symbol('step 0'), Symbol('step 1'), Symbol('step 2'), Symbol('step 3'), Symbol('step 4')];
+
+const executionFlow = {
+  [executionSteps[0]]: {
+    propset_Name: jest.fn(),
+    propset_Value: jest.fn(),
+  },
+  [executionSteps[1]]: {
+    propset_ContentEncoding: jest.fn(),
+    propset_Content: jest.fn(),
+    SignCades: jest.fn(() => executionSteps[4]),
+  },
+  [executionSteps[2]]: {
+    propset_Certificate: jest.fn(),
+    AuthenticatedAttributes2: executionSteps[3],
+    propset_Options: jest.fn(),
+  },
+  [executionSteps[3]]: {
+    Add: jest.fn(),
+  },
+  [executionSteps[4]]: 'signature',
+};
+
+window.cadesplugin.__defineExecutionFlow(executionFlow);
+window.cadesplugin.CreateObjectAsync.mockImplementation((object) => {
+  switch (object) {
+    case 'CADESCOM.CPAttribute':
+      return executionSteps[0];
+    case 'CAdESCOM.CadesSignedData':
+      return executionSteps[1];
+    case 'CAdESCOM.CPSigner':
+      return executionSteps[2];
+  }
+});
+
+describe('createAttachedSignature', () => {
+  test('uses Buffer to encrypt the message', async () => {
+    const originalBufferFrom = (window as any).Buffer.from;
+
+    (window as any).Buffer.from = jest.fn(() => ({
+      toString: jest.fn(),
+    }));
+
+    await createAttachedSignature(parsedCertificateMock.thumbprint, 'message');
+
+    expect((window as any).Buffer.from).toHaveBeenCalledTimes(1);
+
+    (window as any).Buffer.from = originalBufferFrom;
+  });
+
+  test('uses specified certificate', async () => {
+    await createAttachedSignature(parsedCertificateMock.thumbprint, 'message');
+
+    expect(_getCadesCert).toHaveBeenCalledWith(parsedCertificateMock.thumbprint);
+  });
+
+  test('returns signature', async () => {
+    const signature = await createAttachedSignature(parsedCertificateMock.thumbprint, 'message');
+
+    expect(signature).toEqual('signature');
+  });
+});
diff --git a/src/api/createSignature.test.ts b/src/api/createSignature.test.ts
index 80cbf46..fcf495d 100644
--- a/src/api/createSignature.test.ts
+++ b/src/api/createSignature.test.ts
@@ -1,4 +1,5 @@
 import 'cadesplugin';
+import 'console-mock';
 import { rawCertificates, parsedCertificates } from '../__mocks__/certificates';
 import { createSignature } from './createSignature';
 import { _getCadesCert } from '../helpers/_getCadesCert';
diff --git a/src/api/isValidSystemSetup.test.ts b/src/api/isValidSystemSetup.test.ts
index ff255de..1bac2c3 100644
--- a/src/api/isValidSystemSetup.test.ts
+++ b/src/api/isValidSystemSetup.test.ts
@@ -1,5 +1,5 @@
 import 'cadesplugin';
-import 'console-error';
+import 'console-mock';
 import { isValidSystemSetup } from './isValidSystemSetup';
 import { getSystemInfo } from './getSystemInfo';
 import { _isSupportedCadesVersion } from '../helpers/_isSupportedCadesVersion';
diff --git a/src/helpers/_afterPluginsLoaded.test.ts b/src/helpers/_afterPluginsLoaded.test.ts
index a27a7fb..22ce20c 100644
--- a/src/helpers/_afterPluginsLoaded.test.ts
+++ b/src/helpers/_afterPluginsLoaded.test.ts
@@ -1,5 +1,5 @@
 import 'cadesplugin';
-import 'console-error';
+import 'console-mock';
 import { _afterPluginsLoaded } from './_afterPluginsLoaded';
 
 const cadesPluginMock = window.cadesplugin;