Files
dotfiles/modules/claude-code/skills/test-driven-development/mocking.md
alexion b7363ed7e1 feat(claude-code): manage the user's global config in the Module
Bring the declarative half of ~/.claude into modules/claude-code and apply
it when the Module is enabled: the global agent instructions (context =
./CLAUDE.md), the skills tree (skills = ./skills), the attention-bell hook,
and settings.json (model = opus plus the Stop/Notification/SessionStart
hook wiring).

Runtime state (projects, plugins, cache, history, sessions) and the
.credentials.json secret are left out, so login survives rebuilds and no
secret enters the repo. Verified against the built home-files that
~/.claude/{CLAUDE.md,settings.json,skills,hooks/attention-bell.sh} are
generated, the hook executable.
2026-07-19 07:57:43 -04:00

1.4 KiB

When to Mock

Mock at system boundaries only:

  • External APIs (payment, email, etc.)
  • Databases (sometimes - prefer test DB)
  • Time/randomness
  • File system (sometimes)

Don't mock:

  • Your own classes/modules
  • Internal collaborators
  • Anything you control

Designing for Mockability

At system boundaries, design interfaces that are easy to mock:

1. Use dependency injection

Pass external dependencies in rather than creating them internally:

// Easy to mock
function processPayment(order, paymentClient) {
  return paymentClient.charge(order.total);
}

// Hard to mock
function processPayment(order) {
  const client = new StripeClient(process.env.STRIPE_KEY);
  return client.charge(order.total);
}

2. Prefer SDK-style interfaces over generic fetchers

Create specific functions for each external operation instead of one generic function with conditional logic:

// GOOD: Each function is independently mockable
const api = {
  getUser: (id) => fetch(`/users/${id}`),
  getOrders: (userId) => fetch(`/users/${userId}/orders`),
  createOrder: (data) => fetch('/orders', { method: 'POST', body: data }),
};

// BAD: Mocking requires conditional logic inside the mock
const api = {
  fetch: (endpoint, options) => fetch(endpoint, options),
};

The SDK approach means:

  • Each mock returns one specific shape
  • No conditional logic in test setup
  • Easier to see which endpoints a test exercises
  • Type safety per endpoint