tmux TDD Skill
Orchestrate Test-Driven Development in a tmux environment by reading test output directly from panes. Language agnostic.
Environment Layout
┌────────────────┬────────────────┐
│ │ │
│ Pane 0.0 │ Pane 0.1 │
│ Claude Code │ Test Runner │
│ │ │
└────────────────┴────────────────┘
- Pane 0.0: Claude Code (where you are)
- Pane 0.1: Test runner (cargo watch, pytest, jest, go test, etc.)
Instructions
Step 1: Check Current Test Status
Capture output directly from the test pane:
tmux capture-pane -t 0.1 -p -S -50
Options:
-t 0.1: Target pane (test runner)-p: Print to stdout-S -50: Last 50 lines (use-S -for full history)
Step 2: Parse Test Results
Look for pass/fail patterns based on the language:
Rust (cargo test):
test result: ok. 6 passed; 0 failed
test result: FAILED. 4 passed; 2 failed
error[E0425]: cannot find value `x` in this scope
Python (pytest):
6 passed in 0.12s
2 failed, 4 passed in 0.15s
FAILED tests/test_app.py::test_add - AssertionError
E assert 4 == 5
JavaScript (jest/vitest):
Tests: 6 passed, 6 total
Tests: 2 failed, 4 passed, 6 total
FAIL src/app.test.js
✕ should add numbers (5 ms)
Go (go test):
ok mypackage 0.005s
FAIL mypackage 0.005s
--- FAIL: TestAdd (0.00s)
app_test.go:10: expected 5, got 4
Step 3: Make Code Changes
Edit the source files to fix failures. If using a watch mode, tests will automatically re-run.
Step 4: Verify Fix
Wait for tests to re-run, then capture pane again:
tmux capture-pane -t 0.1 -p -S -30
Step 5: Send Commands to Test Pane (if needed)
# Run command in test pane
tmux send-keys -t 0.1 "your-test-command" C-m
# Stop running process
tmux send-keys -t 0.1 C-c
Common Test Commands by Language
| Language | Watch Mode | Single Run |
|---|---|---|
| Rust | cargo watch -x test | cargo test |
| Python | ptw or pytest-watch | pytest |
| JavaScript | jest --watch or vitest | jest or npm test |
| Go | gotestsum --watch | go test ./... |
| Ruby | guard | rspec |
Quick Reference
| Task | Command |
|---|---|
| Read test output | tmux capture-pane -t 0.1 -p -S -50 |
| Full history | tmux capture-pane -t 0.1 -p -S - |
| Send command | tmux send-keys -t 0.1 "command" C-m |
| Stop process | tmux send-keys -t 0.1 C-c |
| List panes | tmux list-panes |
TDD Workflow
- RED: Write a failing test, verify it fails via pane capture
- GREEN: Write minimal code to make it pass
- REFACTOR: Clean up while keeping tests green
Always check test status before and after making changes.
Troubleshooting
Empty pane output?
- Test runner may not be running
- Check:
tmux capture-pane -t 0.1 -p -S -5 - Restart the test watcher in pane 0.1
Can't connect to pane?
- Verify tmux session exists:
tmux list-sessions - List panes:
tmux list-panes