diff --git a/.gitignore b/.gitignore
index f0ccd54e..f8c2f2a0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 .DS_Store
 solaredge-modbus-multi.bbprojectd
 /megalinter-reports
+*.pyc
diff --git a/pyproject.toml b/pyproject.toml
index a8b297ce..5224e1ac 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,3 +4,8 @@ line-length = 88
 [tool.ruff.lint]
 extend-select = ["I"]
 ignore = ["E701"]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+pythonpath = ["."]
+asyncio_mode = "auto"
diff --git a/requirements-test.txt b/requirements-test.txt
index 582ad801..2a2093f4 100644
--- a/requirements-test.txt
+++ b/requirements-test.txt
@@ -1,2 +1,4 @@
 pytest>=8.0.0
 awesomeversion>=25.5.0
+pymodbus>=3.8.3
+pytest-homeassistant-custom-component>=0.13.0
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 00000000..79a6b013
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,3 @@
+"""Activate pytest-homeassistant-custom-component for all tests."""
+
+pytest_plugins = "pytest_homeassistant_custom_component"
diff --git a/tests/test_sensor_scale_factor.py b/tests/test_sensor_scale_factor.py
new file mode 100644
index 00000000..e4f5df64
--- /dev/null
+++ b/tests/test_sensor_scale_factor.py
@@ -0,0 +1,19 @@
+"""Tests for SolarEdgeSensorBase.scale_factor in sensor.py."""
+
+import pytest
+
+from custom_components.solaredge_modbus_multi.sensor import SolarEdgeSensorBase
+
+
+@pytest.mark.parametrize(
+    "value, sf, expected",
+    [
+        (100, -2, 1.0),
+        (500, 1, 5000),
+        (0, -3, 0.0),
+        (-250, -1, -25.0),
+        (1, 0, 1),
+    ],
+)
+def test_scale_factor(value, sf, expected):
+    assert SolarEdgeSensorBase.scale_factor(None, value, sf) == expected