diff --git a/.github/workflows/internal-tests.yaml b/.github/workflows/internal-tests.yaml
new file mode 100644
index 0000000..87ed820
--- /dev/null
+++ b/.github/workflows/internal-tests.yaml
@@ -0,0 +1,30 @@
+name: Internal tests
+
+on:
+  push:
+    branches: [ main ]
+    paths:
+      - 'src/openeo_test_suite/lib/**'
+  pull_request:
+    branches: [ main ]
+    paths:
+      - 'src/openeo_test_suite/lib/**'
+
+jobs:
+  internal-tests:
+    name: "Internal tests"
+    runs-on: ubuntu-latest
+    steps:
+    - name: Clone repo
+      uses: actions/checkout@v2
+    - name: Set up python
+      uses: actions/setup-python@v4
+      with:
+        python-version: 3.9
+        cache: 'pip'
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        python -m pip install .
+    - name: "Internal tests"
+      run: pytest  src/openeo_test_suite/lib/internal-tests/
diff --git a/src/openeo_test_suite/lib/internal-tests/README.md b/src/openeo_test_suite/lib/internal-tests/README.md
new file mode 100644
index 0000000..3c9bb5d
--- /dev/null
+++ b/src/openeo_test_suite/lib/internal-tests/README.md
@@ -0,0 +1,7 @@
+
+# Internal tests
+
+This is an internal test suite for testing the internal
+helpers and other reusable functionality defined in `openeo_test_suite.lib`.
+It is not part of the official test suite, does not run against a real openEO backend
+and should not be run by users of the main openEO test suite.
diff --git a/src/openeo_test_suite/lib/internal-tests/test_backend_under_test.py b/src/openeo_test_suite/lib/internal-tests/test_backend_under_test.py
new file mode 100644
index 0000000..f8a271b
--- /dev/null
+++ b/src/openeo_test_suite/lib/internal-tests/test_backend_under_test.py
@@ -0,0 +1,24 @@
+from unittest import mock
+
+import pytest
+
+from openeo_test_suite.lib.backend_under_test import get_backend_url
+
+
+def test_get_backend_url_default(request):
+    url = get_backend_url(config=request.config)
+    assert url is None
+
+
+@pytest.mark.parametrize(
+    ["configured_url", "expected"],
+    [
+        ("https://openeo.test", "https://openeo.test"),
+        ("openeo.test", "https://openeo.test"),
+    ],
+)
+def test_get_backend_url_mocked_config(configured_url, expected):
+    config = mock.Mock()
+    config.getoption.return_value = configured_url
+    url = get_backend_url(config=config, required=True)
+    assert url == expected