diff --git a/.coveragerc b/.coveragerc
new file mode 100644
index 00000000..48a4e188
--- /dev/null
+++ b/.coveragerc
@@ -0,0 +1,7 @@
+[report]
+exclude_lines =
+    # Have to re-enable the standard pragma
+    pragma: no cover
+
+    # Don't complain if tests don't hit defensive assertion code:
+    raise NotImplementedError
\ No newline at end of file
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 017be7ad..4290b283 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -3,7 +3,16 @@ repos:
   rev: 19.10b0
   hooks:
   - id: black
-    language_version: python3.8
+- repo: https://gitlab.com/pycqa/flake8
+  rev: 3.7.9
+  hooks:
+    - id: flake8
+      files: apps/controllerx
+- repo: https://github.com/pre-commit/mirrors-mypy
+  rev: v0.770
+  hooks:
+    - id: mypy
+      files: apps/controllerx
 - repo: https://github.com/pre-commit/pre-commit-hooks
   rev: v2.4.0
   hooks:
@@ -12,4 +21,12 @@ repos:
     args:
     - --autofix
     - --indent
-    - "4"
\ No newline at end of file
+    - "4"
+- repo: local
+  hooks:
+  - id: pytest
+    name: pytest
+    entry: pytest
+    language: system
+    pass_filenames: false
+    always_run: true
\ No newline at end of file
diff --git a/apps/controllerx/core/controller.py b/apps/controllerx/core/controller.py
index eaf4475d..526cb141 100644
--- a/apps/controllerx/core/controller.py
+++ b/apps/controllerx/core/controller.py
@@ -231,7 +231,7 @@ def get_type_actions_mapping(self) -> TypeActionsMapping:
 class TypeController(Controller, abc.ABC):
     @abc.abstractmethod
     def get_domain(self) -> str:
-        ...
+        raise NotImplementedError
 
     async def check_domain(self, entity: str) -> None:
         domain = self.get_domain()
@@ -277,13 +277,14 @@ async def before_action(self, action: str, *args, **kwargs) -> bool:
         to_return = not (action == "hold" and self.on_hold)
         return await super().before_action(action, *args, **kwargs) and to_return
 
+    @abc.abstractmethod
     async def hold_loop(self, *args) -> bool:
         """
         This function is called by the ReleaseHoldController depending on the settings.
         It stops calling the function once release action is called or when this function
         returns True.
         """
-        return True
+        raise NotImplementedError
 
     def default_delay(self) -> int:
         """
diff --git a/apps/controllerx/core/custom_controller.py b/apps/controllerx/core/custom_controller.py
index 9a1a95bb..df2e085f 100644
--- a/apps/controllerx/core/custom_controller.py
+++ b/apps/controllerx/core/custom_controller.py
@@ -21,7 +21,7 @@ def parse_action(self, action: str) -> TypeAction:
         It should eiter return a value parsed by 'get_type_actions_mapping' or
         a tuple with (function, arg1, arg2, ...).
         """
-        ...
+        raise NotImplementedError
 
     def get_z2m_actions_mapping(self) -> TypeActionsMapping:
         return self.get_custom_mapping()
diff --git a/apps/controllerx/core/integration/__init__.py b/apps/controllerx/core/integration/__init__.py
index 32a124aa..d1ba8fd8 100644
--- a/apps/controllerx/core/integration/__init__.py
+++ b/apps/controllerx/core/integration/__init__.py
@@ -15,15 +15,15 @@ def __init__(self, controller, kwargs: Dict[str, Any]):
 
     @abc.abstractmethod
     def get_name(self) -> str:
-        ...
+        raise NotImplementedError
 
     @abc.abstractmethod
     def get_actions_mapping(self) -> Optional[TypeActionsMapping]:
-        ...
+        raise NotImplementedError
 
     @abc.abstractmethod
     def listen_changes(self, controller_id: str) -> None:
-        ...
+        raise NotImplementedError
 
 
 def _import_modules(file_dir: str, package: str) -> None:
diff --git a/apps/controllerx/core/stepper/__init__.py b/apps/controllerx/core/stepper/__init__.py
index 385907f1..c1d20a92 100644
--- a/apps/controllerx/core/stepper/__init__.py
+++ b/apps/controllerx/core/stepper/__init__.py
@@ -36,4 +36,4 @@ def step(self, value: float, direction: str) -> Tuple[Union[int, float], bool]:
         that needs to take and returns the new value and True
         if the step exceeds the boundaries.
         """
-        ...
+        raise NotImplementedError
diff --git a/tests/core/controller_test.py b/tests/core/controller_test.py
index b33044d6..1bda7d87 100644
--- a/tests/core/controller_test.py
+++ b/tests/core/controller_test.py
@@ -6,10 +6,10 @@
 from core import integration as integration_module
 from core.controller import action
 from tests.test_utils import (
-    hass_mock,
-    fake_controller,
     IntegrationMock,
     fake_async_function,
+    fake_controller,
+    hass_mock,
 )
 
 
@@ -160,6 +160,7 @@ async def test_initialize(
         ("sensor1, sensor2", ["sensor1", "sensor2"]),
         ("sensor1,sensor2", ["sensor1", "sensor2"]),
         (["sensor1", "sensor2"], ["sensor1", "sensor2"]),
+        (0.0, []),
     ],
 )
 def test_get_list(sut, monkeypatch, test_input, expected):
@@ -194,6 +195,7 @@ def test_get_option(sut, option, options, expect_an_error):
             False,
         ),
         ({"test": "no name"}, "z2m", {}, True),
+        (0.0, None, {}, True),
     ],
 )
 def test_get_integration(
@@ -347,3 +349,19 @@ def test_get_action(sut, test_input, expected, error_expected):
     else:
         output = sut.get_action(test_input)
         assert output == expected
+
+
+@pytest.mark.parametrize(
+    "service, attributes",
+    [("test_service", {"attr1": 0.0, "attr2": "test"}), ("test_service", {}),],
+)
+@pytest.mark.asyncio
+async def test_call_service(sut, mocker, service, attributes):
+
+    call_service_stub = mocker.patch.object(hass.Hass, "call_service")
+
+    # SUT
+    await sut.call_service(service, **attributes)
+
+    # Checker
+    call_service_stub.assert_called_once_with(service, **attributes)
diff --git a/tests/core/type/light_controller_test.py b/tests/core/type/light_controller_test.py
index d61aa47d..f3750729 100644
--- a/tests/core/type/light_controller_test.py
+++ b/tests/core/type/light_controller_test.py
@@ -22,23 +22,30 @@ def sut(hass_mock, monkeypatch):
 
 
 @pytest.mark.parametrize(
-    "light_input, light_output",
+    "light_input, light_output, error_expected",
     [
-        ("light.kitchen", {"name": "light.kitchen", "color_mode": "auto"}),
+        ("light.kitchen", {"name": "light.kitchen", "color_mode": "auto"}, False),
         (
             {"name": "light.kitchen", "color_mode": "auto"},
             {"name": "light.kitchen", "color_mode": "auto"},
+            False,
+        ),
+        (
+            {"name": "light.kitchen"},
+            {"name": "light.kitchen", "color_mode": "auto"},
+            False,
         ),
-        ({"name": "light.kitchen"}, {"name": "light.kitchen", "color_mode": "auto"}),
         (
             {"name": "light.kitchen", "color_mode": "color_temp"},
             {"name": "light.kitchen", "color_mode": "color_temp"},
+            False,
         ),
+        (0.0, None, True),
     ],
 )
 @pytest.mark.asyncio
 async def test_initialize_and_get_light(
-    sut, monkeypatch, mocker, light_input, light_output
+    sut, monkeypatch, mocker, light_input, light_output, error_expected
 ):
     super_initialize_stub = mocker.stub()
 
@@ -48,10 +55,17 @@ async def fake_super_initialize(self):
     monkeypatch.setattr(ReleaseHoldController, "initialize", fake_super_initialize)
 
     sut.args["light"] = light_input
-    await sut.initialize()
 
-    super_initialize_stub.assert_called_once()
-    assert sut.light == light_output
+    # SUT
+    if error_expected:
+        with pytest.raises(ValueError) as e:
+            await sut.initialize()
+    else:
+        await sut.initialize()
+
+        # Checks
+        super_initialize_stub.assert_called_once()
+        assert sut.light == light_output
 
 
 @pytest.mark.parametrize(
@@ -97,20 +111,34 @@ def test_get_attribute(
 
 
 @pytest.mark.parametrize(
-    "attribute_input, expected_output",
-    [("xy_color", 0), ("brightness", 3.0), ("color_temp", 1),],
+    "attribute_input, expected_output, error_expected",
+    [
+        ("xy_color", 0, False),
+        ("brightness", 3.0, False),
+        ("color_temp", 1, False),
+        ("xy_color", 0, False),
+        ("brightness", None, True),
+        ("color_temp", None, True),
+    ],
 )
 @pytest.mark.asyncio
-async def test_get_value_attribute(sut, monkeypatch, attribute_input, expected_output):
+async def test_get_value_attribute(
+    sut, monkeypatch, attribute_input, expected_output, error_expected
+):
     async def fake_get_entity_state(entity, attribute):
         return expected_output
 
     monkeypatch.setattr(sut, "get_entity_state", fake_get_entity_state)
 
     # SUT
-    output = await sut.get_value_attribute(attribute_input)
+    if error_expected:
+        with pytest.raises(ValueError) as e:
+            await sut.get_value_attribute(attribute_input)
+    else:
+        output = await sut.get_value_attribute(attribute_input)
 
-    assert output == expected_output
+        # Checks
+        assert output == expected_output
 
 
 @pytest.mark.parametrize(
@@ -459,15 +487,24 @@ def fake_get_attribute(*args, **kwargs):
         super_hold_patch.assert_called_with(attribute_input, expected_direction)
 
 
+@pytest.mark.parametrize(
+    "value_attribute", [10, None],
+)
 @pytest.mark.asyncio
-async def test_hold_loop(sut, mocker):
+async def test_hold_loop(sut, mocker, value_attribute):
     attribute = "test_attribute"
     direction = Stepper.UP
-    sut.value_attribute = 10
+    sut.value_attribute = value_attribute
     change_light_state_patch = mocker.patch.object(sut, "change_light_state")
     stepper = MinMaxStepper(1, 10, 10)
     sut.automatic_steppers = {attribute: stepper}
-    await sut.hold_loop(attribute, direction)
-    change_light_state_patch.assert_called_once_with(
-        sut.value_attribute, attribute, direction, stepper, "hold"
-    )
+
+    # SUT
+    exceeded = await sut.hold_loop(attribute, direction)
+
+    if value_attribute is None:
+        assert exceeded == True
+    else:
+        change_light_state_patch.assert_called_once_with(
+            sut.value_attribute, attribute, direction, stepper, "hold"
+        )
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 38a02f35..7bf32607 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -30,7 +30,7 @@ def fake_fn(*args, **kwargs):
     monkeypatch.setattr(hass.Hass, "listen_event", fake_fn)
     monkeypatch.setattr(hass.Hass, "listen_state", fake_fn)
     monkeypatch.setattr(hass.Hass, "log", fake_fn)
-    monkeypatch.setattr(hass.Hass, "call_service", fake_fn)
+    monkeypatch.setattr(hass.Hass, "call_service", fake_async_function())
 
 
 @pytest.fixture