Generating CLI Tests Agent Skill
Generate pytest tests for Typer CLI commands. Includes fixtures (temp_storage, sample_data), CliRunner patterns, confirmation handling (y/n/--force), and edge case coverage. Use when user asks to "write tests for", "test my CLI", "add test coverage", or any CLI + test request.
Install
one command, takes just this skill from the repositorynpx skills add https://github.com/https-deeplearning-ai/sc-agent-skills-files --skill generating-cli-testsThe instruction itself
13 sections, as written by the authorGenerating CLI Tests
Patterns for generating tests for Typer CLI commands.
Workflow
- Identify command type (Create/Read/Update/Delete/Bulk)
- Ensure fixtures exist in
conftest.py - Write tests using scenarios below
- Run tests to verify
Fixtures (conftest.py)
import json
import pytest
from typer.testing import CliRunner
@pytest.fixture
def runner():
"""CLI test runner."""
return CliRunner()
@pytest.fixture
def temp_storage(tmp_path, monkeypatch):
"""Empty storage for testing."""
storage_dir = tmp_path / ".task"
storage_dir.mkdir()
storage_file = storage_dir / "tasks.json"
storage_file.write_text(json.dumps({"version": 1, "tasks": []}))
monkeypatch.setenv("TASK_STORAGE_PATH", str(storage_file))
return storage_file
@pytest.fixture
def sample_data(temp_storage):
"""Pre-populated storage."""
data = {
"version": 1,
"tasks": [
{"title": "First task", "done": False, "priority": "low", "created_at": "2025-01-01T10:00:00", "due_date": None},
{"title": "Second task", "done": True, "priority": "high", "created_at": "2025-01-01T11:00:00", "due_date": None},
]
}
temp_storage.write_text(json.dumps(data))
return data
Test Structure (AAA)
def test_<command>_<scenario>(runner, temp_storage):
# Arrange - via fixtures
# Act
result = runner.invoke(app, ["<command>", "<args>"])
# Assert
assert result.exit_code == 0
assert "<expected>" in result.output
CliRunner Usage
from typer.testing import CliRunner
from task.main import app
runner = CliRunner()
# Basic
result = runner.invoke(app, ["add", "New task"])
# With options
result = runner.invoke(app, ["add", "Task", "--priority", "high"])
# With confirmation
result = runner.invoke(app, ["clear", "1"], input="y\n") # Accept
result = runner.invoke(app, ["clear", "1"], input="n\n") # Decline
# Skip confirmation
result = runner.invoke(app, ["clear", "1", "--force"])
Test Scenarios by Command Type
Create/Add
class TestAdd:
def test_adds_task(self, runner, temp_storage):
result = runner.invoke(app, ["add", "New task"])
assert result.exit_code == 0
assert "Added" in result.output
def test_with_priority(self, runner, temp_storage):
result = runner.invoke(app, ["add", "Task", "--priority", "high"])
assert result.exit_code == 0
def test_empty_title_shows_error(self, runner, temp_storage):
result = runner.invoke(app, ["add", ""])
assert result.exit_code == 2
Read/List
class TestList:
def test_shows_tasks(self, runner, sample_data):
result = runner.invoke(app, ["list"])
assert result.exit_code == 0
assert "First task" in result.output
def test_empty_state(self, runner, temp_storage):
result = runner.invoke(app, ["list"])
assert "No tasks" in result.output or "empty" in result.output.lower()
def test_with_filter(self, runner, sample_data):
result = runner.invoke(app, ["list", "--done"])
assert result.exit_code == 0
Update/Done
class TestDone:
def test_marks_done(self, runner, sample_data):
result = runner.invoke(app, ["done", "1"])
assert result.exit_code == 0
def test_not_found(self, runner, temp_storage):
result = runner.invoke(app, ["done", "999"])
assert result.exit_code == 1
assert "not found" in result.output.lower()
Delete/Clear
class TestClear:
def test_confirmed(self, runner, sample_data):
result = runner.invoke(app, ["clear", "1"], input="y\n")
assert result.exit_code == 0
assert "Deleted" in result.output
def test_declined(self, runner, sample_data):
result = runner.invoke(app, ["clear", "1"], input="n\n")
assert "Cancelled" in result.output
def test_force(self, runner, sample_data):
result = runner.invoke(app, ["clear", "1", "--force"])
assert result.exit_code == 0
def test_not_found(self, runner, temp_storage):
result = runner.invoke(app, ["clear", "999", "--force"])
assert result.exit_code == 1
Edge Cases to Cover
| Category | Test Cases |
|----------|------------|
| Invalid Input | Empty string, wrong type, out of range |
| Not Found | ID doesn't exist |
| Boundary | Zero, negative, first/last item |
| State | Already done, empty storage |
| Confirmation | Accept (y), decline (n), force flag |
Checklist
- [ ] Test file:
tests/test_<command>.py - [ ] Fixtures in
conftest.py - [ ] Uses
CliRunnerfromtyper.testing - [ ] AAA structure (Arrange, Act, Assert)
- [ ] Tests exit codes: 0, 1, 2
- [ ] Destructive commands: tests y/n and
--force - [ ] Output assertions check expected messages
Running Tests
uv run pytest # All tests
uv run pytest -v # Verbose
uv run pytest tests/test_add.py # Specific file
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How to use it
Take https-deeplearning-ai/generating-cli-tests from the repository into ~/.claude/skills for personal
use, or into .claude/skills inside a project.
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same name cannot sit side by side — one of them will be ignored.