Feature/12 implement usethis tool deptry (#13)

* Add deptry function which installs deptry via uv as a dev dependency.

* Add progress message for usethis tool deptry.

* Add tests for running deptry after calling `usethis tool deptry`.

* Remove hello function.

* Configure the package as a CLI app using typer.

* Reword message for usethis tool deptry

* Reword message for usethis tool deptry

* Use rich for console output

* Set PYTHONIOENCODING explicitly in CI config.

.github/workflows/ci.yml

@@ -7,6 +7,8 @@ on:
 jobs:
   tests:
     runs-on: ${{ matrix.os }}
+    env:
+      PYTHONIOENCODING: utf-8
     steps:
       - name: Checkout code
         uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7

pyproject.toml

@@ -4,7 +4,13 @@ version = "0.1.0"
 description = "Add your description here"
 readme = "README.md"
 requires-python = ">=3.12"
-dependencies = []
+dependencies = [
+    "rich>=13.8.1",
+    "typer>=0.12.5",
+]
+
+[project.scripts]
+usethis = "usethis.__main__:app"
 
 [build-system]
 requires = ["hatchling"]
@@ -15,4 +21,7 @@ dev-dependencies = [
     "pytest>=8.3.2",
     "pytest-md>=0.2.0",
     "pytest-emoji>=0.2.0",
+    "pydantic>=2.9.1",
+    "tomlkit>=0.13.2",
+    "deptry>=0.20.0",
 ]

src/usethis/__init__.py

@@ -1,2 +1,3 @@
-def hello() -> str:
-    return "Hello from usethis!"
+from rich.console import Console
+
+console = Console()

src/usethis/__main__.py

@@ -0,0 +1,12 @@
+import typer
+
+import usethis.tool
+
+app = typer.Typer(
+    help=(
+        "🤖 Automate Python package and project setup tasks that are otherwise "
+        "performed manually."
+    )
+)
+app.add_typer(usethis.tool.app, name="tool")
+app(prog_name="usethis")

src/usethis/tool.py

@@ -0,0 +1,15 @@
+import subprocess
+
+import typer
+
+from usethis import console
+
+app = typer.Typer(help="Add and configure development tools, e.g. linters")
+
+
+@app.command(
+    help="Use the deptry linter: avoid missing or superfluous dependency declarations."
+)
+def deptry() -> None:
+    console.print("✔ Ensuring deptry is a development dependency", style="green")
+    subprocess.run(["uv", "add", "--dev", "--quiet", "deptry"], check=True)

tests/usethis/test_tool.py

@@ -0,0 +1,82 @@
+import os
+import subprocess
+from contextlib import contextmanager
+from pathlib import Path
+from typing import Generator
+
+import pytest
+import tomlkit
+from pydantic import TypeAdapter
+
+from usethis.tool import deptry
+
+
+@contextmanager
+def change_cwd(new_dir: Path) -> Generator[None, None, None]:
+    """Change the working directory temporarily."""
+    old_dir = Path.cwd()
+    os.chdir(new_dir)
+    try:
+        yield
+    finally:
+        os.chdir(old_dir)
+
+
+@pytest.fixture
+def uv_init_dir(tmp_path: Path) -> None:
+    subprocess.run(["uv", "init"], cwd=tmp_path, check=True)
+    return tmp_path
+
+
+class TestDeptry:
+    def test_dependency_added(self, uv_init_dir: Path):
+        # Act
+        with change_cwd(uv_init_dir):
+            deptry()
+
+        # Assert
+        (dev_dep,) = _get_dev_deps(uv_init_dir)
+        assert dev_dep.startswith("deptry>=")
+
+    def test_stdout(self, uv_init_dir: Path, capfd: pytest.CaptureFixture[str]):
+        # Act
+        with change_cwd(uv_init_dir):
+            deptry()
+
+        # Assert
+        out, _ = capfd.readouterr()
+        assert out == "✔ Ensuring deptry is a development dependency\n"
+
+    def test_run_deptry_fail(self, uv_init_dir: Path):
+        # Arrange
+        f = uv_init_dir / "bad.py"
+        f.write_text("import broken_dependency")
+
+        # Act
+        with change_cwd(uv_init_dir):
+            deptry()
+
+        # Assert
+        with pytest.raises(subprocess.CalledProcessError):
+            subprocess.run(["deptry", "."], cwd=uv_init_dir, check=True)
+
+    def test_run_deptry_pass(self, uv_init_dir: Path):
+        # Arrange
+        f = uv_init_dir / "good.py"
+        f.write_text("import sys")
+
+        # Act
+        with change_cwd(uv_init_dir):
+            deptry()
+
+        # Assert
+        subprocess.run(["deptry", "."], cwd=uv_init_dir, check=True)
+
+    def test_cli(self, uv_init_dir: Path):
+        subprocess.run(["usethis", "tool", "deptry"], cwd=uv_init_dir, check=True)
+
+
+def _get_dev_deps(proj_dir: Path) -> list[str]:
+    pyproject = tomlkit.parse((proj_dir / "pyproject.toml").read_text())
+    dev_deps = pyproject["tool"]["uv"]["dev-dependencies"]
+    return TypeAdapter(list[str]).validate_python(dev_deps)