diff --git a/pyproject.toml b/pyproject.toml
index 50bb169..e088713 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -75,7 +75,7 @@ select = [
     "UP",  # pyupgrade
     "W",   # pycodestyle
 ]
-ignore = ["D203", "D107"]
+ignore = ["D203", "D107", "D212"]
 src = ["src", "tests"]
 
 [tool.ruff.per-file-ignores]
diff --git a/src/pybuild_deps/compile_build_dependencies.py b/src/pybuild_deps/compile_build_dependencies.py
index 1170f1f..6828c68 100644
--- a/src/pybuild_deps/compile_build_dependencies.py
+++ b/src/pybuild_deps/compile_build_dependencies.py
@@ -1,3 +1,11 @@
+"""
+compile build dependencies module.
+
+Heavily rely on pip-tools BacktrackingResolver and our own find_build_deps
+to recursively find all build dependencies and generate a pinned list
+of build dependencies.
+"""
+
 from __future__ import annotations
 
 from typing import Iterable
diff --git a/src/pybuild_deps/constants.py b/src/pybuild_deps/constants.py
index 5e404f3..d55c365 100644
--- a/src/pybuild_deps/constants.py
+++ b/src/pybuild_deps/constants.py
@@ -1,3 +1,5 @@
+"""constants for pybuild deps."""
+
 from pip._internal.utils.appdirs import user_cache_dir
 from xdg import xdg_cache_home
 
diff --git a/src/pybuild_deps/exceptions.py b/src/pybuild_deps/exceptions.py
index 0dea5ab..77743cb 100644
--- a/src/pybuild_deps/exceptions.py
+++ b/src/pybuild_deps/exceptions.py
@@ -1,2 +1,5 @@
+"""custom exceptions for pybuild-deps."""
+
+
 class PyBuildDepsError(Exception):
-    ...
+    """Custom exception for pybuild-deps."""
diff --git a/src/pybuild_deps/logger.py b/src/pybuild_deps/logger.py
index 171647c..2af6dac 100644
--- a/src/pybuild_deps/logger.py
+++ b/src/pybuild_deps/logger.py
@@ -1,3 +1,6 @@
+"""custom logger for pybuild-deps."""
+# ruff: noqa: D102
+
 from __future__ import annotations
 
 import logging
@@ -10,7 +13,12 @@
 
 
 class Logger:
-    """Custom logger for pybuild-deps."""
+    """
+    Custom logger for pybuild-deps.
+
+    When invoked as a CLI, will use click to log messages. Otherwise
+    will use default python logger.
+    """
 
     def __init__(self, verbosity: int = 0):
         self._verbosity = verbosity
diff --git a/src/pybuild_deps/parsers/requirements.py b/src/pybuild_deps/parsers/requirements.py
index 4b6885a..1615ad2 100644
--- a/src/pybuild_deps/parsers/requirements.py
+++ b/src/pybuild_deps/parsers/requirements.py
@@ -1,3 +1,5 @@
+"""parser for requirement.txt files."""
+
 from __future__ import annotations
 
 import optparse
@@ -25,6 +27,7 @@ def parse_requirements(
     constraint: bool = False,
     isolated: bool = False,
 ) -> Generator[InstallRequirement]:
+    """Thin wrapper around pip's `parse_requirements`."""
     for parsed_req in _parse_requirements(
         filename, session, finder=finder, options=options, constraint=constraint
     ):
diff --git a/src/pybuild_deps/scripts/compile.py b/src/pybuild_deps/scripts/compile.py
index b29ba7f..6eb4348 100644
--- a/src/pybuild_deps/scripts/compile.py
+++ b/src/pybuild_deps/scripts/compile.py
@@ -1,3 +1,5 @@
+"""compile script."""
+
 from __future__ import annotations
 
 import os
@@ -78,7 +80,7 @@ def get_compile_command(click_ctx):
     default=False,
     help="Generate pip 8 style hashes in the resulting requirements file.",
 )
-@click.argument("src_files", nargs=-1, type=click.Path(exists=True, allow_dash=True))
+@click.argument("src_files", nargs=-1, type=click.Path(exists=True, allow_dash=False))
 @click.option(
     "--cache-dir",
     help="Store the cache data in DIRECTORY.",
@@ -104,34 +106,16 @@ def cli(
     """Compiles build_requirements.txt from requirements.txt."""
     log.verbosity = verbose - quiet
     if len(src_files) == 0:
-        if Path(REQUIREMENTS_TXT).exists():
-            src_files = (REQUIREMENTS_TXT,)
-        else:
-            raise click.BadParameter(
-                f"Couldn't find a '{REQUIREMENTS_TXT}'. "
-                "You must specify at least one input file."
-            )
+        src_files = _handle_src_files()
     if not output_file and not dry_run:
         log.warning("No output file (-o) specified. Defaulting to 'dry run' mode.")
         dry_run = True
 
-    pip_args = []
-    repository = PyPIRepository(pip_args, cache_dir=cache_dir)
+    repository = PyPIRepository([], cache_dir=cache_dir)
 
     dependencies: list[InstallRequirement] = []
     for src_file in src_files:
-        try:
-            dependencies.extend(
-                parse_requirements(
-                    src_file,
-                    finder=repository.finder,
-                    session=repository.session,
-                    options=repository.options,
-                )
-            )
-        except PyBuildDepsError as err:
-            log.error(str(err))
-            sys.exit(2)
+        dependencies.extend(_parse_requirements(repository, src_file))
 
     compiler = BuildDependencyCompiler(repository)
     try:
@@ -178,3 +162,30 @@ def cli(
 
     if dry_run:
         log.info("Dry-run, so no file created/updated.")
+
+
+def _parse_requirements(repository, src_file):
+    try:
+        return list(
+            parse_requirements(
+                src_file,
+                finder=repository.finder,
+                session=repository.session,
+                options=repository.options,
+            )
+        )
+    except PyBuildDepsError as err:
+        log.error(str(err))
+        sys.exit(2)
+
+
+def _handle_src_files():
+    if Path(REQUIREMENTS_TXT).exists():
+        src_files = (REQUIREMENTS_TXT,)
+    else:
+        raise click.BadParameter(
+            f"Couldn't find a '{REQUIREMENTS_TXT}'. "
+            "You must specify at least one input file."
+        )
+
+    return src_files
diff --git a/tests/test_compile_build_dependencies.py b/tests/test_compile_build_dependencies.py
index 4cc212e..7350d04 100644
--- a/tests/test_compile_build_dependencies.py
+++ b/tests/test_compile_build_dependencies.py
@@ -1,3 +1,5 @@
+"""test compile_build_dependencies module."""
+
 import pytest
 from pip._internal.req.constructors import install_req_from_req_string
 from piptools.repositories import PyPIRepository
@@ -9,11 +11,13 @@
 
 @pytest.fixture
 def compiler() -> BuildDependencyCompiler:
+    """BuildDependencyCompiler instance."""
     repo = PyPIRepository([], cache_dir=PIP_CACHE_DIR)
     return BuildDependencyCompiler(repo)
 
 
 def test_compile_greenpath(compiler):
+    """Test compiling build dependencies happy path."""
     ireq = install_req_from_req_string("cryptography==40.0.0")
     dependencies = compiler.resolve([ireq])
     deps_per_name = {req.name: req for req in dependencies}
@@ -23,6 +27,7 @@ def test_compile_greenpath(compiler):
 
 
 def test_unpinned_dependency(compiler):
+    """Ensure unpinned dependencies will raise the appropriate error."""
     ireq = install_req_from_req_string("cryptography<40")
     with pytest.raises(PyBuildDepsError):
         compiler.resolve([ireq])
diff --git a/tests/test_main.py b/tests/test_main.py
index 34883c3..0079745 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -16,6 +16,7 @@
 
 @pytest.fixture
 def pypi_repo():
+    """PyPIRepository instance for testing."""
     return PyPIRepository([], cache_dir=PIP_CACHE_DIR)
 
 
@@ -65,6 +66,7 @@ def test_find_build_deps(
 
 @pytest.mark.e2e
 def test_compile_greenpath(runner: CliRunner, tmp_path: Path, pypi_repo):
+    """Test happy path for compile command."""
     output = tmp_path / "requirements-build.txt"
     requirements_path: Path = tmp_path / "requirements.txt"
     requirements_path.write_text("cryptography==39.0.0")
@@ -78,6 +80,7 @@ def test_compile_greenpath(runner: CliRunner, tmp_path: Path, pypi_repo):
 
 
 def test_compile_missing_requirements_txt(runner: CliRunner, tmp_path: Path):
+    """Test compile without a requirements.txt."""
     chdir(tmp_path)
     result = runner.invoke(main.cli, args=["compile"])
     assert result.exit_code != 0
@@ -97,6 +100,7 @@ def test_compile_implicit_requirements_txt_and_non_default_options(
     cache: Path,
     args,
 ):
+    """Exercise some options to ensure they are working."""
     chdir(tmp_path)
     requirements_path: Path = tmp_path / "requirements.txt"
     requirements_path.write_text("setuptools-rust==1.6.0")
@@ -106,6 +110,7 @@ def test_compile_implicit_requirements_txt_and_non_default_options(
 
 
 def test_compile_not_pinned_requirements_txt(runner: CliRunner, tmp_path: Path):
+    """Ensure the appropriate error is thrown for non pinned requirements."""
     chdir(tmp_path)
     requirements_path: Path = tmp_path / "requirements.txt"
     requirements_path.write_text("setuptools-rust<1")
@@ -119,6 +124,7 @@ def test_compile_not_pinned_requirements_txt(runner: CliRunner, tmp_path: Path):
 
 
 def test_compile_unsolvable_dependencies(runner: CliRunner, tmp_path: Path, mocker):
+    """Test error handling for unsolvable dependencies."""
     mocker.patch.object(
         BuildDependencyCompiler, "resolve", side_effect=PipToolsError("SOME ERROR")
     )
diff --git a/tests/test_parsers/test_requirements.py b/tests/test_parsers/test_requirements.py
index 97d78f6..e470811 100644
--- a/tests/test_parsers/test_requirements.py
+++ b/tests/test_parsers/test_requirements.py
@@ -1,3 +1,5 @@
+"""test requirements parser."""
+
 from pathlib import Path
 
 import pytest
@@ -7,6 +9,7 @@
 
 
 def test_pinned_requirements(tmp_path, mocker):
+    """Test parsing requirements with pinned dependencies."""
     requirements_path: Path = tmp_path / "requirements.txt"
     requirements_path.write_text("cryptography==40.0.0")
     requirements_list = list(parse_requirements(str(requirements_path), mocker.Mock()))
@@ -14,6 +17,7 @@ def test_pinned_requirements(tmp_path, mocker):
 
 
 def test_unpinned_requirements(tmp_path, mocker):
+    """Test parsing requirements with unpinned dependencies."""
     requirements_path: Path = tmp_path / "requirements.txt"
     requirements_path.write_text("cryptography>40")
     with pytest.raises(PyBuildDepsError):