How to Speed Up Your CI with TestCaddy

TestCaddy Best Practices: Tips from the ProsTestCaddy is a lightweight test runner and orchestration tool designed to simplify test execution across multiple environments and CI systems. When used well, it reduces flaky tests, speeds up feedback loops, and makes test suites more maintainable. This article collects proven best practices from experienced engineers who’ve scaled TestCaddy in production — practical tips you can apply today.

Start with a clear test strategy

Before optimizing TestCaddy itself, define what your tests should achieve.

Classify tests: unit, integration, end-to-end (E2E), performance, and flaky/regression tests. Treat each class differently.
Determine failure SLAs: which failures block merges vs. which can be triaged later.
Define test owners and run policies: who owns failures, who is responsible for flaky tests, and when certain suites should run (on every commit, nightly, or pre-release).

Keep TestCaddy configuration simple and explicit

Sensible configuration avoids surprises later.

Use small, modular config files rather than one giant file.
Keep environment-specific overrides in separate files (e.g., testcaddy.yml, testcaddy.ci.yml).
Version-control your configs with the code they test so changes are reviewed alongside code changes.
Prefer explicit settings over implicit defaults. If TestCaddy has a timeout default, set it in your config so it’s obvious to future readers.

Parallelize intelligently

TestCaddy supports parallel execution; use it to reduce wall-clock test time, but follow these rules:

Parallelize at the test-suite level rather than indiscriminately at the test-case level to avoid shared state issues.
Start with conservative concurrency (2–4 workers) and increase while monitoring for resource contention.
Ensure tests are hermetic: avoid shared files, ports, or global state. Use ephemeral resources or containerized environments where possible.

Isolate flaky tests

Flakes are productivity killers. Treat them as first-class citizens.

Tag flaky tests so TestCaddy can run them separately or with retries.
Record detailed failure logs and test metadata (environment, seed, timestamps) to reproduce flakes.
Use TestCaddy’s retry feature cautiously — retries can hide real issues if overused.

Use environment provisioning and cleanup hooks

Consistent environment setup prevents nondeterministic failures.

Use before/after hooks to provision databases, mock services, or seed data.
Make cleanup idempotent so aborted runs don’t leave leftover state.
Prefer ephemeral resources (containers, temporary databases) and tear them down in after hooks.

Cache and artifact management

Good caching dramatically speeds CI.

Cache dependencies (language runtimes, package managers) between runs.
Persist build artifacts that many tests reuse (compiled binaries, test fixtures).
Clean caches periodically to avoid stale artifacts causing false positives.

Integrate with CI/CD thoughtfully

TestCaddy works best when CI pipeline steps reflect test priorities.

Fast, critical tests should run on pull requests; heavyweight suites can run on nightly builds or gated merges.
Use TestCaddy’s exit codes and reports to gate merges and trigger rollbacks.
Parallelize CI jobs with TestCaddy’s orchestration to maximize resource utilization.

Monitor, measure, and act on test metrics

Metrics help prioritize test maintenance.

Track test durations, failure rates, flakiness, and execution frequency.
Set alerts for spikes in failures or increased build times.
Use dashboards to spot regressions after merges and to identify slow or flaky suites to optimize.

Improve test reliability with deterministic practices

Determinism makes test runs predictable and debuggable.

Seed random generators and expose seeds in logs to reproduce failures.
Freeze time where appropriate or use controllable clock mocks.
Avoid relying on external network services in unit tests; use lightweight stubs or local mocks.

Mock external dependencies smartly

Mocks speed up tests and reduce brittleness, but misuse can hide integration issues.

Mock at the network boundary: keep internal logic unmocked to preserve coverage.
Use contract tests between your code and external services to ensure mocks stay accurate.
For E2E tests, include a few runs against real services or dedicated test instances.

Organize tests for clarity and maintainability

Readable test suites are easier to run and debug.

Name test files and cases clearly with intent-focused descriptions.
Group related tests into focused suites and use tags to select appropriate runs.
Keep tests small; a test that exercises many things is harder to maintain.

Secure your test infrastructure

Tests can leak secrets or become attack vectors if not managed.

Avoid hard-coded credentials in test configs; use dynamic secrets or CI secret stores.
Limit network access for test runners and use isolated networks for integration tests.
Review third-party test fixtures and dependencies for security risks.

Automate test health checks and maintenance

Set a regular cadence to reduce test debt.

Run weekly or nightly pipelines that aggressively surface flaky and slow tests.
Assign engineers to periodically triage and fix the worst offenders.
Use TestCaddy reports to auto-open issues for tests that cross failure or flakiness thresholds.

Leverage TestCaddy features and plugins

Explore built-in features and community plugins to fit your workflow.

Use TestCaddy’s reporting formats (JUnit, JSON) for CI and dashboard integration.
Enable parallelization, retries, and selective runs with TestCaddy flags where appropriate.
Integrate with observability tools to capture test run logs and traces for deeper debugging.

Common pitfalls and how to avoid them

Over-parallelizing without addressing shared resources → leads to intermittent failures. Fix by isolating resources and decreasing concurrency.
Over-relying on retries → hides real regressions. Use retries only for known flakiness and pair with root-cause tracking.
Letting slow suites run on every PR → slows developers. Move heavy suites to nightly or pre-merge gates.
Not versioning test data or fixtures → leads to nondeterministic failures. Store fixtures alongside code and update with PRs.

Example TestCaddy configuration patterns

Use modular configs and environment overrides. Example (conceptual):

# testcaddy.yml suites:   unit:     concurrency: 4     tags: [fast]     retries: 0   integration:     concurrency: 2     tags: [db]     retries: 1 hooks:   before_all: scripts/provision_test_env.sh   after_all: scripts/cleanup_test_env.sh

Quick checklist to adopt today

Tag and separate flaky tests.
Add timeouts and seeds for determinism.
Cache dependencies in CI.
Run critical suites on PRs; heavy suites nightly.
Monitor test metrics and assign ownership for flaky tests.

TestCaddy’s value scales with discipline: small changes in test organization, caching, and CI integration can yield large improvements in speed and reliability. Apply the above practices incrementally — start with flaky-test isolation and CI caching, then expand to parallelization and automated maintenance.