diff --git a/.githooks/pre-push b/.githooks/pre-push
index 4f83ec2..e18b142 100755
--- a/.githooks/pre-push
+++ b/.githooks/pre-push
@@ -26,9 +26,13 @@ cargo build --features extension-module
 # Python E2E (mirrors the ci.yml `python-e2e` job). Best-effort: needs a local
 # .venv with maturin installed. CI is the authoritative gate.
 if [ -x .venv/bin/maturin ]; then
-  echo "[pre-push] maturin develop + Python E2E vs git"
-  .venv/bin/maturin develop --release >/dev/null
-  .venv/bin/python python/tests/test_e2e.py
+  echo "[pre-push] maturin develop + pytest coverage"
+  .venv/bin/maturin develop --release --extras dev >/dev/null
+  .venv/bin/python -m pytest python/tests/ --cov=gitxtend --cov-fail-under=80
+elif [ -x .venv/Scripts/maturin.exe ]; then
+  echo "[pre-push] maturin develop + pytest coverage"
+  .venv/Scripts/maturin.exe develop --release --extras dev >/dev/null
+  .venv/Scripts/python.exe -m pytest python/tests/ --cov=gitxtend --cov-fail-under=80
 else
   echo "[pre-push] (skipping Python E2E — no .venv/bin/maturin; gated by CI python-e2e)"
 fi
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2c86634..bc9137f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -54,5 +54,5 @@ jobs:
         run: |
           python -m venv .venv
           .venv/bin/pip install -q maturin
-          .venv/bin/maturin develop --release
-          .venv/bin/python python/tests/test_e2e.py
+          .venv/bin/maturin develop --release --extras dev
+          .venv/bin/python -m pytest python/tests/ --cov=gitxtend --cov-fail-under=80
diff --git a/.gitignore b/.gitignore
index ac87805..78764b9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,11 +7,14 @@ Cargo.lock
 __pycache__/
 *.py[cod]
 *.so
+*.pdb
 .venv/
 build/
 dist/
 *.egg-info/
 wheels/
+.coverage
+htmlcov/
 
 # Editor / OS
 .DS_Store
diff --git a/pyproject.toml b/pyproject.toml
index e6a7927..ff27e9a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -19,6 +19,13 @@ classifiers = [
 [project.urls]
 Repository = "https://github.com/hartsock/gitxtend"
 
+[project.optional-dependencies]
+dev = [
+    "pytest>=8,<9",
+    "pytest-cov>=6,<7",
+    "pytest-mock>=3,<4",
+]
+
 [tool.maturin]
 # Compiled module imported as `import gitxtend`. Type stubs in python/gitxtend.
 # `extension-module` is a crate feature that layers on `python` (which pulls
@@ -27,3 +34,20 @@ Repository = "https://github.com/hartsock/gitxtend"
 features = ["extension-module"]
 python-source = "python"
 module-name = "gitxtend._gitxtend"
+
+[tool.pytest.ini_options]
+addopts = [
+    "--strict-markers",
+]
+markers = [
+    "integration: tests that exercise the compiled extension and real git CLI",
+]
+testpaths = ["python/tests"]
+
+[tool.coverage.run]
+branch = true
+source = ["gitxtend"]
+omit = ["python/tests/*"]
+
+[tool.coverage.report]
+fail_under = 80
diff --git a/python/tests/conftest.py b/python/tests/conftest.py
new file mode 100644
index 0000000..7e5d6cb
--- /dev/null
+++ b/python/tests/conftest.py
@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+from unittest.mock import MagicMock
+
+import pytest
+
+
+PLANNED_WRITE_EXTENSION_NAMES = (
+    "pull",
+    "push",
+    "add",
+    "commit",
+    "stash_push",
+    "stash_pop",
+    "create_branch",
+    "reset_hard",
+    "rebase",
+    "stash_rebase",
+)
+
+
+@pytest.fixture
+def mock_gitxtend(monkeypatch):
+    """Patch the compiled extension surface for Python unit tests."""
+    import gitxtend
+    import gitxtend._gitxtend as extension
+
+    mock_extension = MagicMock(name="gitxtend._gitxtend")
+    public_extension_names = (*gitxtend.__all__, *PLANNED_WRITE_EXTENSION_NAMES)
+
+    for name in public_extension_names:
+        mock = MagicMock(name=f"gitxtend._gitxtend.{name}")
+        setattr(mock_extension, name, mock)
+        monkeypatch.setattr(extension, name, mock, raising=False)
+        monkeypatch.setattr(gitxtend, name, mock, raising=False)
+
+    return mock_extension
diff --git a/python/tests/test_e2e.py b/python/tests/test_e2e.py
index ec022f1..9a17163 100644
--- a/python/tests/test_e2e.py
+++ b/python/tests/test_e2e.py
@@ -17,6 +17,9 @@
 import unittest
 
 import gitxtend
+import pytest
+
+pytestmark = pytest.mark.integration
 
 _ENV = {
     **os.environ,
diff --git a/python/tests/test_mock_fixture.py b/python/tests/test_mock_fixture.py
new file mode 100644
index 0000000..606104c
--- /dev/null
+++ b/python/tests/test_mock_fixture.py
@@ -0,0 +1,34 @@
+from __future__ import annotations
+
+import gitxtend
+from conftest import PLANNED_WRITE_EXTENSION_NAMES
+
+
+def test_mock_gitxtend_fixture_replaces_extension_exports(mock_gitxtend):
+    mock_gitxtend.is_git_repo.return_value = True
+
+    assert gitxtend.is_git_repo("/tmp/repo") is True
+    mock_gitxtend.is_git_repo.assert_called_once_with("/tmp/repo")
+
+
+def test_mock_gitxtend_fixture_includes_write_side_exports(mock_gitxtend):
+    write_side_calls = {
+        "pull": ("/tmp/repo",),
+        "push": ("/tmp/repo", "origin", "main"),
+        "add": ("/tmp/repo", ["README.md"]),
+        "commit": ("/tmp/repo", "initial import"),
+        "stash_push": ("/tmp/repo", "before-rebase"),
+        "stash_pop": ("/tmp/repo",),
+        "create_branch": ("/tmp/repo", "feature/test"),
+        "reset_hard": ("/tmp/repo", "HEAD~1"),
+        "rebase": ("/tmp/repo", "origin/main"),
+        "stash_rebase": ("/tmp/repo", "origin/main"),
+    }
+
+    assert set(write_side_calls) == set(PLANNED_WRITE_EXTENSION_NAMES)
+
+    for name, args in write_side_calls.items():
+        getattr(mock_gitxtend, name).return_value = name
+
+        assert getattr(gitxtend, name)(*args) == name
+        getattr(mock_gitxtend, name).assert_called_once_with(*args)