Testing Logging

Testing & Logging Best Practices

Quick Start

Structured Logging (pino)

import pino from "pino"

export const logger = pino({
  level: process.env.LOG_LEVEL || "info",
  transport:
    process.env.NODE_ENV === "development"
      ? { target: "pino-pretty" }
      : undefined,
})

// Usage
logger.info({ port: 3000, env: "production" }, "Server started")
logger.error({ error, context: "riskyOperation" }, "Operation failed")

Log Levels

Testing Pyramid

Unit Tests (Vitest)

import { describe, expect, it } from "vitest"

describe("formatDate", () => {
  it("formats ISO date to readable string", () => {
    expect(formatDate("2025-01-22T10:00:00Z")).toBe("January 22, 2025")
  })
})

React Component Tests

import { render, screen } from "@testing-library/react"
import userEvent from "@testing-library/user-event"

it("calls onClick when clicked", async () => {
  const
  render(<Button
  await userEvent.click(screen.getByRole("button"))
  expect(onClick).toHaveBeenCalledOnce()
})

Query Priority (prefer top)

1. getByRole — Accessible name (best)
2. getByLabelText — Form labels
3. getByText — Text content
4. getByTestId — Last resort

Test Commands

pnpm test              # All tests
pnpm test:watch        # Watch mode
pnpm test:coverage     # With coverage

Additional Resources

• For complete patterns including mocking, integration tests, providers, and coverage config, see reference.md