diff --git a/.github/workflows/pylint.yml b/.github/workflows/pylint.yml
index f9dcc8e..56cb694 100644
--- a/.github/workflows/pylint.yml
+++ b/.github/workflows/pylint.yml
@@ -20,7 +20,7 @@ jobs:
         pip install pylint
     - name: pylint
       run: |
-        pylint $(git ls-files '*.py') --fail-under=9.0 --output-format=json > pylint-report.json
+        pylint $(git ls-files '*.py' | grep -v '^test/') --fail-under=9.0 --output-format=json > pylint-report.json
 
     - name: Generate Pylint Score
       id: pylint_score
diff --git a/.github/workflows/pytest.yml b/.github/workflows/pytest.yml
new file mode 100644
index 0000000..45bcc80
--- /dev/null
+++ b/.github/workflows/pytest.yml
@@ -0,0 +1,29 @@
+name: PyTest
+
+on: [push]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: '3.10'
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install -r requirements_dev.txt
+    - name: Test with pytest
+      run: |
+        mkdir -p junit
+        pytest test/ --doctest-modules --junitxml=junit/test-results.xml --cov=superfaktura --cov-report=xml --cov-report=html
+    - name: Upload pytest test results
+      uses: actions/upload-artifact@v4
+      with:
+        name: pytest-results
+        path: junit/test-results.xml
+      # Use always() to always run this step to publish test results when there are test failures
+      if: ${{ always() }}
diff --git a/requirements.txt b/requirements.txt
index ca6d6b6..6079683 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,3 @@
 requests~=2.32.3
-python-dotenv~=1.0.1
\ No newline at end of file
+python-dotenv~=1.0.1
+setuptools~=75.8.0
\ No newline at end of file
diff --git a/requirements_dev.txt b/requirements_dev.txt
new file mode 100644
index 0000000..a34cc3b
--- /dev/null
+++ b/requirements_dev.txt
@@ -0,0 +1,4 @@
+requests~=2.32.3
+python-dotenv~=1.0.1
+pytest~=8.3.5
+pytest-cov
diff --git a/test/__init__.py b/test/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/test/test_superfaktura_api.py b/test/test_superfaktura_api.py
new file mode 100644
index 0000000..c4e295e
--- /dev/null
+++ b/test/test_superfaktura_api.py
@@ -0,0 +1,88 @@
+import os
+import pytest
+from unittest.mock import patch, mock_open, MagicMock
+
+import requests
+
+from superfaktura.superfaktura_api import (
+    SuperFakturaAPI,
+    SuperFakturaAPIException,
+    SuperFakturaAPIMissingCredentialsException,
+)
+
+@pytest.fixture
+def api():
+    with patch.dict(os.environ, {
+        "SUPERFAKTURA_API_KEY": "test_key",
+        "SUPERFAKTURA_API_URL": "https://api.superfaktura.cz",
+        "SUPERFAKTURA_API_EMAIL": "test_email",
+        "SUPERFAKTURA_API_COMPANY_ID": "test_company_id"
+    }):
+        return SuperFakturaAPI()
+
+def test_missing_credentials():
+    with patch.dict(os.environ, {}, clear=True):
+        with pytest.raises(SuperFakturaAPIMissingCredentialsException):
+            SuperFakturaAPI()
+
+def test_get(api):
+    with patch("requests.get") as mock_get:
+        mock_get.return_value.status_code = 200
+        mock_get.return_value.json.return_value = {"data": "test"}
+        response = api.get("test_endpoint")
+        assert response == {"data": "test"}
+
+def test_get_failure(api):
+    with patch("requests.get") as mock_get:
+        mock_get.return_value.status_code = 404
+        with pytest.raises(SuperFakturaAPIException):
+            api.get("test_endpoint")
+
+def test_download(api):
+    with patch("requests.get") as mock_get:
+        mock_get.return_value.status_code = 200
+        mock_get.return_value.content = b"test_content"
+        with patch("builtins.open", mock_open()) as mock_file:
+            with open("test_file", "wb") as f:
+                api.download("test_endpoint", f)
+            mock_file().write.assert_called_once_with(b"test_content")
+
+def test_download_failure(api):
+    with patch("requests.get") as mock_get:
+        mock_get.return_value.status_code = 404
+        with patch("builtins.open", mock_open()):
+            with open("test_file", "wb") as f:
+                with pytest.raises(SuperFakturaAPIException):
+                    api.download("test_endpoint", f)
+
+def test_post(api):
+    with patch("requests.post") as mock_post:
+        mock_post.return_value.status_code = 200
+        mock_post.return_value.json.return_value = {"data": "test"}
+        response = api.post("test_endpoint", '{"name": "Example"}')
+        assert response == {"data": "test"}
+
+def test_post_failure(api):
+    with patch("requests.post") as mock_post:
+        mock_post.return_value.status_code = 404
+        mock_post.return_value.json.return_value = {"error": "not found"}
+        with pytest.raises(SuperFakturaAPIException):
+            api.post("test_endpoint", '{"name": "Example"}')
+
+def test_get_invalid_json(api):
+    with patch("requests.get") as mock_get:
+        mock_response = MagicMock()
+        mock_response.status_code = 200
+        mock_response.json.side_effect = requests.exceptions.JSONDecodeError("msg", "doc", 0)
+        mock_get.return_value = mock_response
+        with pytest.raises(SuperFakturaAPIException, match="Unable to decode response as JSON"):
+            api.get("test_endpoint")
+
+def test_download_not_writable_descriptor(api):
+    with patch("requests.get") as mock_get:
+        mock_get.return_value.status_code = 200
+        mock_get.return_value.content = b"test_content"
+        mock_descriptor = MagicMock()
+        mock_descriptor.writable.return_value = False
+        with pytest.raises(SuperFakturaAPIException, match=" is not writable"):
+            api.download("test_endpoint", mock_descriptor)