diff --git a/.coveragerc b/.coveragerc
new file mode 100644
index 0000000..5951051
--- /dev/null
+++ b/.coveragerc
@@ -0,0 +1,4 @@
+[report]
+
+exclude_lines =
+    if __name__ == .__main__.:
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
index 7de892e..904c4c4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,5 @@
 .idea
 main_version
-branch_version
\ No newline at end of file
+branch_version
+src/__pycache__/*
+tests/__pycache__/*
\ No newline at end of file
diff --git a/.pylintrc b/.pylintrc
index 25749b5..fad2aa6 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -6,7 +6,8 @@ max-line-length=120
 # Disable various warnings:
 
 # W0237 Disabled as it makes the code more readable
-disable=W0237
+# R0801 Disabled as it's a small amount of duplication
+disable=W0237, R0801
 
 [MASTER]
 init-hook='import sys; sys.path.append("src")'
\ No newline at end of file
diff --git a/docker-compose.yml b/docker-compose.yml
index 95d571b..200a798 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -1,3 +1,3 @@
 services:
   self-test:
-    image: some/test:0.4.7
+    image: some/test:0.4.8
diff --git a/pytest.ini b/pytest.ini
new file mode 100644
index 0000000..3b93724
--- /dev/null
+++ b/pytest.ini
@@ -0,0 +1,5 @@
+[pytest]
+pythonpath = src
+testpaths = tests
+python_files = *.py
+python_functions = test_*
diff --git a/src/base.py b/src/base.py
index b2e6a20..84a79f1 100644
--- a/src/base.py
+++ b/src/base.py
@@ -1,4 +1,5 @@
 """This is the base module including helper/abstract classes and errors."""
+
 from abc import ABC, abstractmethod
 from pathlib import Path
 from typing import Union
@@ -31,5 +32,5 @@ def get_version(content: str) -> Version:
 
     @staticmethod
     @abstractmethod
-    def compare(version1: Version, version2: Version) -> Union[True, VersionNotUpdated]:
+    def compare(version1: Version, version2: Version) -> Union[bool, VersionNotUpdated]:
         """This method should compare the versions and return a bool status"""
diff --git a/src/comparison.py b/src/comparison.py
index 9e279dc..6cc1c3c 100644
--- a/src/comparison.py
+++ b/src/comparison.py
@@ -1,6 +1,7 @@
 """The comparison module which is where the main check classes are."""
+
 from pathlib import Path
-from typing import Union, List
+from typing import Union, List, Type
 
 from packaging.version import Version
 from base import Base, VersionNotUpdated
@@ -51,7 +52,7 @@ def get_version(content: str) -> Version:
         return Version(content)
 
     @staticmethod
-    def compare(main: Version, branch: Version) -> Union[True, VersionNotUpdated]:
+    def compare(main: Version, branch: Version) -> Union[bool, Type[VersionNotUpdated]]:
         """
         Returns if the branch version is larger than the main version
         :param main: Version on main
@@ -99,7 +100,7 @@ def read_files(app: Path, compose: Path) -> (str, List):
         return content1, content2
 
     @staticmethod
-    def get_version(content: str) -> Version:
+    def get_version(content: List[str]) -> Version:
         """
         This method returns the version from the file as an object
         For compose versions we have to do some data handling.
@@ -114,7 +115,7 @@ def get_version(content: str) -> Version:
         return Version(version_str)
 
     @staticmethod
-    def compare(app: Version, compose: Version) -> Union[True, VersionNotUpdated]:
+    def compare(app: Version, compose: Version) -> Union[bool, Type[VersionNotUpdated]]:
         """
         Returns if the application version and docker compose version are equal.
         :param app: App version
diff --git a/src/main.py b/src/main.py
index d830360..8286bb5 100644
--- a/src/main.py
+++ b/src/main.py
@@ -15,8 +15,8 @@ def main():
     root_path = Path(os.environ.get("GITHUB_WORKSPACE"))
     main_path = root_path / "main"
     branch_path = root_path / "branch"
-    with open(branch_path / app_path, "r", encoding='utf-8') as release_file:
-        release_version = release_file.read().strip('\n')
+    with open(branch_path / app_path, "r", encoding="utf-8") as release_file:
+        release_version = release_file.read().strip("\n")
 
     CompareAppVersion().run(main_path / app_path, branch_path / app_path)
     if compose_path:
@@ -24,7 +24,7 @@ def main():
         CompareComposeVersion().run(branch_path / app_path, branch_path / compose_path)
 
     github_env = os.getenv("GITHUB_ENV")
-    with open(github_env, "a", encoding='utf-8') as env:
+    with open(github_env, "a", encoding="utf-8") as env:
         # We can assume either/both of these values returned true otherwise they would have errored
         env.write("app_updated=true\n")
         if compose_path:
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_compare_app_version.py b/tests/test_compare_app_version.py
new file mode 100644
index 0000000..37033db
--- /dev/null
+++ b/tests/test_compare_app_version.py
@@ -0,0 +1,66 @@
+"""Tests for comparison.CompareAppVersion"""
+from unittest.mock import patch, mock_open
+from pathlib import Path
+from packaging.version import Version
+import pytest
+from comparison import CompareAppVersion, VersionNotUpdated
+
+
+@pytest.fixture(name="instance", scope="function")
+def instance_fixture():
+    """Provide a fixture instance for the tests"""
+    return CompareAppVersion()
+
+
+@patch("comparison.CompareAppVersion.compare")
+@patch("comparison.CompareAppVersion.get_version")
+@patch("comparison.CompareAppVersion.read_files")
+def test_run(mock_read, mock_get_version, mock_compare, instance):
+    """Test the run method makes correct calls."""
+    mock_path1 = Path("mock1")
+    mock_path2 = Path("mock2")
+    mock_read.return_value = ("1.0.0", "1.0.1")
+    mock_get_version.side_effect = [Version("1.0.0"), Version("1.0.0")]
+    mock_compare.return_value = True
+    res = instance.run(mock_path1, mock_path2)
+    mock_read.assert_called_once_with(mock_path1, mock_path2)
+    mock_get_version.assert_any_call("1.0.0")
+    mock_get_version.assert_any_call("1.0.1")
+    mock_compare.assert_called_once_with(Version("1.0.0"), Version("1.0.0"))
+    assert res
+
+
+@patch("comparison.CompareAppVersion.compare")
+@patch("comparison.CompareAppVersion.get_version")
+@patch("comparison.CompareAppVersion.read_files")
+def test_run_fails(mock_read, _, mock_compare, instance):
+    """Test the run method fails."""
+    mock_read.return_value = ("mock1", "mock2")
+    mock_compare.side_effect = VersionNotUpdated()
+    with pytest.raises(VersionNotUpdated):
+        instance.run(Path("mock1"), Path("mock2"))
+
+
+def test_read_files(instance):
+    """Test the read files method returns a tuple"""
+    with patch("builtins.open", mock_open(read_data="1.0.0")):
+        res = instance.read_files(Path("mock1"), Path("mock2"))
+    assert res == ("1.0.0", "1.0.0")
+
+
+def test_get_version(instance):
+    """Test a version object is returned"""
+    res = instance.get_version("1.0.0")
+    assert isinstance(res, Version)
+
+
+def test_compare_pass(instance):
+    """Test that the compare returns true for a valid comparison"""
+    res = instance.compare(Version("1.0.0"), Version("1.0.1"))
+    assert res != VersionNotUpdated
+
+
+def test_compare_fails(instance):
+    """Test that the compare returns an error for an invalid comparison"""
+    res = instance.compare(Version("1.0.1"), Version("1.0.0"))
+    assert res == VersionNotUpdated
diff --git a/tests/test_compare_compose_version.py b/tests/test_compare_compose_version.py
new file mode 100644
index 0000000..8356b67
--- /dev/null
+++ b/tests/test_compare_compose_version.py
@@ -0,0 +1,65 @@
+"""Tests for comparison.CompareComposeVersion"""
+from unittest.mock import patch, mock_open
+from pathlib import Path
+import pytest
+from packaging.version import Version
+from comparison import CompareComposeVersion, VersionNotUpdated
+
+
+@pytest.fixture(name="instance", scope="function")
+def instance_fixture():
+    """Provide a fixture instance for the tests"""
+    return CompareComposeVersion()
+
+
+@patch("comparison.CompareComposeVersion.compare")
+@patch("comparison.CompareComposeVersion.get_version")
+@patch("comparison.CompareComposeVersion.read_files")
+def test_run(mock_read, mock_get_version, mock_compare, instance):
+    """Test the run method makes correct calls."""
+    mock_path1 = Path("mock1")
+    mock_path2 = Path("mock2")
+    mock_read.return_value = ("1.0.0", "1.0.0")
+    mock_get_version.side_effect = [Version("1.0.0"), Version("1.0.0")]
+    mock_compare.return_value = True
+    res = instance.run(mock_path1, mock_path2)
+    mock_read.assert_called_once_with(mock_path1, mock_path2)
+    mock_get_version.assert_any_call("1.0.0")
+    mock_compare.assert_called_once_with(Version("1.0.0"), Version("1.0.0"))
+    assert res
+
+
+@patch("comparison.CompareComposeVersion.compare")
+@patch("comparison.CompareComposeVersion.get_version")
+@patch("comparison.CompareComposeVersion.read_files")
+def test_run_fails(mock_read, _, mock_compare, instance):
+    """Test the run method fails."""
+    mock_read.return_value = ("1.0.0", "1.0.1")
+    mock_compare.side_effect = VersionNotUpdated()
+    with pytest.raises(VersionNotUpdated):
+        instance.run(Path("mock1"), Path("mock2"))
+
+
+def test_read_files(instance):
+    """Test the read files method returns a tuple"""
+    with patch("builtins.open", mock_open(read_data="1.0.0")):
+        res = instance.read_files(Path("mock1"), Path("mock2"))
+    assert res == ("1.0.0", ["1.0.0"])
+
+
+def test_get_version(instance):
+    """Test a version object is returned"""
+    res = instance.get_version(["image: some/image:1.0.0\n"])
+    assert isinstance(res, Version)
+
+
+def test_compare_pass(instance):
+    """Test that the compare returns true for a valid comparison"""
+    res = instance.compare(Version("1.0.0"), Version("1.0.0"))
+    assert res != VersionNotUpdated
+
+
+def test_compare_fails(instance):
+    """Test that the compare returns an error for an invalid comparison"""
+    res = instance.compare(Version("1.0.1"), Version("1.0.0"))
+    assert res == VersionNotUpdated
diff --git a/tests/test_main.py b/tests/test_main.py
new file mode 100644
index 0000000..6a977aa
--- /dev/null
+++ b/tests/test_main.py
@@ -0,0 +1,25 @@
+"""Tests for main"""
+from unittest.mock import patch, mock_open
+from pathlib import Path
+from main import main
+
+
+@patch("main.CompareComposeVersion")
+@patch("main.CompareAppVersion")
+@patch("main.os")
+def test_main(mock_os, mock_compare_app, mock_compare_compose):
+    """Test the main method runs correctly."""
+    mock_os.environ.get.side_effect = [Path("app"), Path("compose"), Path("workspace")]
+    with patch("builtins.open", mock_open(read_data="1.0.0")):
+        main()
+    mock_os.environ.get.assert_any_call("INPUT_APP_VERSION_PATH")
+    mock_os.environ.get.assert_any_call("INPUT_DOCKER_COMPOSE_PATH")
+    mock_os.environ.get.assert_any_call("GITHUB_WORKSPACE")
+    mock_branch_path = Path("workspace") / "branch"
+    mock_main_path = Path("workspace") / "main"
+    mock_compare_app.return_value.run.assert_called_once_with(
+        mock_main_path / "app", mock_branch_path / "app"
+    )
+    mock_compare_compose.return_value.run.assert_called_once_with(
+        mock_branch_path / "app", mock_branch_path / "compose"
+    )
diff --git a/version.txt b/version.txt
index 5546bd2..c650d5a 100644
--- a/version.txt
+++ b/version.txt
@@ -1 +1 @@
-0.4.7
\ No newline at end of file
+0.4.8
\ No newline at end of file