# Testing and safety

Prove a schema change is correct and safe before it reaches a database, and turn that proof into a CI gate.

Source: https://docs.ptah.run/v0.8.0/testing/overview/

import { LinkCard, CardGrid } from '@astrojs/starlight/components';

Every check here answers one question and no more than one. Knowing which
question a green result answered is the difference between a gate and a habit.

## Checks

<CardGrid>
  <LinkCard title="Test migrations and schemas" href="../migrations-and-schema/" description="Run cases against throwaway databases and assert what the change did, not only that it ran." />
  <LinkCard title="Run checks in CI" href="../ci/" description="Turn those checks into a pull-request gate, and read the exit codes correctly." />
  <LinkCard title="Lint migration SQL" href="../../versioned/lint/" description="Catch destructive and backward-incompatible statements before a database sees them." />
  <LinkCard title="Validate a schema file" href="../../schema/validate-and-format/" description="Fail on a structural problem, or on a declaration a target would silently drop." />
  <LinkCard title="Report security findings" href="../../schema/security/" description="Surface privilege, owner and role findings in the desired schema." />
  <LinkCard title="Keep history verifiable" href="../../versioned/integrity-and-safety/" description="What the integrity file proves, and what it does not." />
</CardGrid>

## What each answer covers

A test asserts a change's effect on a throwaway database. A lint finding is
about the SQL as written, with no database involved. Validation is about the
desired schema alone. None of them observes the database you are about to
change, which is what [drift detection](../../direct/compare-and-drift/) is
for.

So a green pull request means the change is correct in isolation. Whether the
target is in the state the change assumes is a separate question, asked
against that target.

## Choose the database

Use a throwaway database for tests, a dev or shadow database for replay and
planning, and a reviewed target URL for a real apply. These roles are not
interchangeable, and
[database URLs and dev databases](../../concepts/database-urls-and-dev-databases/)
defines each one.

## Reference

[Exit codes](../../reference/exit-codes/) is the automation contract,
[lint rules](../../reference/lint-rules/) enumerates every rule identifier, and
[test cases](../../reference/test-cases/) is the exact case format.