diff --git a/README.md b/README.md
index f44347d..4b33580 100644
--- a/README.md
+++ b/README.md
@@ -26,7 +26,7 @@ To set up additional external tools that are used:
       * Run `diffoscope --list-tools` for a full list. Also, the Dockerfile
       should install all of them.
 
-Note that it is much simpler to run Vessel in a Docker container, which already contains all these dependencies. See [Docker Setup](#docker).
+Note that it is much simpler to run Vessel in a Docker container, which already contains all these dependencies. See [Docker Setup](#docker-setup).
 
 ### Docker Setup
 
@@ -65,14 +65,19 @@ Example running on two images from a private Docker registry:
 
 ## Development
 
-To lint the code, execute:
-* `ruff check`
+Follow the instructions at [Local Environment Setup](#local-environment-setup) first to set up your local environment.
 
-To apply the safe lint fixes, execute:
-* `ruff check --fix`
+To lint the code, and check for format and type issues, execute:
+* `make check`
 
-To format the code, execute:
-* `ruff format`
+To apply the safe lint fixes, and format fixes, execute:
+* `make qa`
+
+To run unit tests, execute:
+* `make test`
+
+To run all the above, execute:
+* `make ci`
 
 ### Building
 
diff --git a/poetry.lock b/poetry.lock
index ffc3b9a..3aa8b1e 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -529,6 +529,17 @@ files = [
 docs = ["Sphinx", "furo"]
 test = ["objgraph", "psutil"]
 
+[[package]]
+name = "iniconfig"
+version = "2.0.0"
+description = "brain-dead simple config-ini parsing"
+optional = false
+python-versions = ">=3.7"
+files = [
+    {file = "iniconfig-2.0.0-py3-none-any.whl", hash = "sha256:b6a85871a79d2e3b22d2d1b94ac2824226a63c6b741c88f7ae975f18b6778374"},
+    {file = "iniconfig-2.0.0.tar.gz", hash = "sha256:2d91e135bf72d31a410b17c16da610a82cb55f6b0477d1a902134b24a455b8b3"},
+]
+
 [[package]]
 name = "ipython"
 version = "8.29.0"
@@ -1407,6 +1418,21 @@ docs = ["furo (>=2024.8.6)", "proselint (>=0.14)", "sphinx (>=8.0.2)", "sphinx-a
 test = ["appdirs (==1.4.4)", "covdefaults (>=2.3)", "pytest (>=8.3.2)", "pytest-cov (>=5)", "pytest-mock (>=3.14)"]
 type = ["mypy (>=1.11.2)"]
 
+[[package]]
+name = "pluggy"
+version = "1.5.0"
+description = "plugin and hook calling mechanisms for python"
+optional = false
+python-versions = ">=3.8"
+files = [
+    {file = "pluggy-1.5.0-py3-none-any.whl", hash = "sha256:44e1ad92c8ca002de6377e165f3e0f1be63266ab4d554740532335b9d75ea669"},
+    {file = "pluggy-1.5.0.tar.gz", hash = "sha256:2cffa88e94fdc978c4c574f15f9e59b7f4201d439195c3715ca9e2486f1d0cf1"},
+]
+
+[package.extras]
+dev = ["pre-commit", "tox"]
+testing = ["pytest", "pytest-benchmark"]
+
 [[package]]
 name = "portion"
 version = "2.6.0"
@@ -1538,6 +1564,26 @@ docs = ["myst_parser", "sphinx", "sphinx_rtd_theme"]
 full = ["Pillow (>=8.0.0)", "PyCryptodome", "cryptography"]
 image = ["Pillow (>=8.0.0)"]
 
+[[package]]
+name = "pytest"
+version = "7.4.4"
+description = "pytest: simple powerful testing with Python"
+optional = false
+python-versions = ">=3.7"
+files = [
+    {file = "pytest-7.4.4-py3-none-any.whl", hash = "sha256:b090cdf5ed60bf4c45261be03239c2c1c22df034fbffe691abe93cd80cea01d8"},
+    {file = "pytest-7.4.4.tar.gz", hash = "sha256:2cf0005922c6ace4a3e2ec8b4080eb0d9753fdc93107415332f50ce9e7994280"},
+]
+
+[package.dependencies]
+colorama = {version = "*", markers = "sys_platform == \"win32\""}
+iniconfig = "*"
+packaging = "*"
+pluggy = ">=0.12,<2.0"
+
+[package.extras]
+testing = ["argcomplete", "attrs (>=19.2.0)", "hypothesis (>=3.56)", "mock", "nose", "pygments (>=2.7.2)", "requests", "setuptools", "xmlschema"]
+
 [[package]]
 name = "python-dateutil"
 version = "2.9.0.post0"
@@ -1883,4 +1929,4 @@ dev = ["black (>=19.3b0)", "pytest (>=4.6.2)"]
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.11"
-content-hash = "775f14982a8ebb35d53757778229aeda596a889ccb706592451859a6042fe1c8"
+content-hash = "4421746b635668569027efc5dcfda13e561a92ff71af6ccbbdc227359b2b101f"
diff --git a/pyproject.toml b/pyproject.toml
index b65cd76..34e6c4b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -40,6 +40,7 @@ ruff = "^0.7.4"
 mypy = "^1.13.0"
 types-PyYAML = "^6.0.12"
 actionlint-py = "^1.7.4.18"
+pytest = "^7.3.1"
 
 [build-system]
 requires = ["poetry-core"]
diff --git a/test/__init__.py b/test/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/vessel/cli.py b/vessel/cli.py
index 95bef27..edb1260 100644
--- a/vessel/cli.py
+++ b/vessel/cli.py
@@ -79,8 +79,8 @@ def vessel(logging_level: str) -> None:
         resolve_path=True,
     ),
     help=(
-        "Specify a data directory for unpacking the images. Default: Create a temporary directory that is "
-        "auto-deleted."
+        "Specify a data directory for unpacking the images. Default: Create a "
+        "temporary directory that is auto-deleted."
     ),
 )
 @click.option(
@@ -93,7 +93,8 @@ def vessel(logging_level: str) -> None:
         resolve_path=True,
     ),
     help=(
-        "Specify a output directory for diffoscope output. Default: Stores in current directory."
+        "Specify a output directory for diffoscope output. Default: Stores "
+        "in current directory."
     ),
 )
 def diff(
diff --git a/vessel/utils/diffoscope.py b/vessel/utils/diffoscope.py
index b2f5d44..33b9eb0 100644
--- a/vessel/utils/diffoscope.py
+++ b/vessel/utils/diffoscope.py
@@ -186,7 +186,8 @@ def parse_diffoscope_output(
                     (
                         diff.comments != []
                         and not any(
-                            flag.regex["comment"].search(comment) for comment in diff.comments
+                            flag.regex["comment"].search(comment) 
+                            for comment in diff.comments
                         )
                     )
                     or (