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06 Numbers and Powers

AI-Generated Code: When to Trust It and How to Verify

Card No. 06·29175 · Updated · Standard formula, shown below

Trust AI-generated code only after you have verified that it meets the requirements, behaves correctly on relevant tests, and is safe for its context. Treat it as a draft from a fast but fallible contributor: the more consequential the code or the less familiar the system, the more independent review it needs.

Why AI code needs verification

Code-generation tools produce suggestions from patterns learned from their training data and, in some cases, from context supplied in a prompt or project. They can generate plausible syntax and familiar programming patterns quickly, but plausible is not the same as correct. A snippet may compile while mishandling an edge case, using an outdated interface, making an unsafe assumption, or failing to fit the surrounding application.

Generated code has no special guarantee of correctness just because it is fluent, well formatted, or accompanied by an explanation. Explanations can also be wrong. The right standard is the same one applied to code from any source: check the requirements, inspect the implementation, and gather evidence through tests and review.

Start with the task’s risk

Verification should be proportional to what failure could do. A short script that reformats disposable data is different from code that handles authentication, payments, personal information, production infrastructure, or safety-critical operations. Consider both the likelihood of a defect and its potential impact.

  • Lower risk: a small, reversible change with clear expected output, such as formatting a local text file. Review the logic and run it on representative examples.
  • Moderate risk: application features, database queries, or changes affecting multiple components. Check interfaces, edge cases, automated tests, and compatibility with the project.
  • High risk: security-sensitive, privacy-sensitive, financial, infrastructure, or safety-related code. Require careful human review by someone who understands the domain, plus appropriate testing and established release controls. Do not rely on an AI explanation as approval.

If you cannot explain what a generated change does, where its inputs come from, and what happens when it fails, you are not ready to trust it in production.

A practical verification workflow

  1. Define the expected behavior. Write down inputs, outputs, constraints, failure cases, and relevant compatibility requirements before judging the result. For example, a date parser should have a defined policy for invalid dates and time zones.
  2. Review the change in context. Read every changed line, not only the summary. Check how the code interacts with callers, data models, error handling, dependencies, and project conventions. Look for unnecessary changes that make review harder.
  3. Check names and interfaces. Confirm that functions, libraries, configuration keys, and API calls exist in the versions actually used by the project. Consult the project’s documentation or installed package definitions rather than trusting a generated citation or remembered example.
  4. Run automated checks. Use the project’s formatter, linter, type checker, build, and relevant test suite. A passing build shows that code meets some mechanical requirements; it does not prove the behavior is correct.
  5. Test boundaries and failure paths. Add or run tests for empty inputs, unusual values, invalid data, permission failures, timeouts, and other cases relevant to the feature. Compare results with an independently worked-out expected result where possible.
  6. Review security and data handling. Check input validation, authorization, secrets, logging, file and network access, and dependency changes. Use established security review practices, especially when code processes untrusted input.
  7. Deploy cautiously. Follow normal code review and release procedures. For changes with meaningful operational risk, use suitable monitoring and a rollback plan rather than assuming tests cover every real-world condition.

Common failure patterns

Generated code often fails in ways that look reasonable at first glance. It may solve a nearby problem rather than the one specified, omit validation, swallow an exception, mishandle concurrency, or make assumptions about input format. It may also invent a library method, mix incompatible versions, or include a dependency that the project does not need.

For example, a function that calculates an average might work for ordinary numbers but divide by zero on an empty collection. A database query might return the expected result for a small test while being inefficient or exposing records that should be restricted. These are not reasons to reject every generated suggestion; they are reasons to test the properties that matter rather than only the happy path.

Watch for tests that merely repeat the implementation’s assumptions. If the code and its test were generated from the same mistaken interpretation, both may agree and still be wrong. Validate expected behavior against requirements, domain knowledge, or a separate trusted reference.

Privacy, dependencies, and project context

Before sending code or prompts to an external service, follow your organization’s rules for source code, customer data, credentials, and other confidential material. Do not paste secrets such as access tokens or private keys into a prompt. Redact sensitive values and share only the context needed to explain the task. Tool policies and data handling differ, so check the terms and settings that apply to the service you use.

Generated suggestions can also introduce third-party packages or copy code with uncertain provenance. Review each new dependency for necessity, maintenance, compatibility, and the project’s licensing and security requirements. Do not assume that a package is trustworthy merely because a tool recommended it.

When AI is useful—and when to slow down

AI assistance is often most useful for bounded tasks with clear acceptance criteria: drafting boilerplate, explaining unfamiliar code, suggesting test cases, or proposing a small refactor. It can help you explore alternatives, but you still need to compare those alternatives against the actual project and its constraints.

Slow down when the prompt is ambiguous, the change is large, the code touches security boundaries, or you lack the expertise to assess the result. Break broad work into small reviewable changes. Ask for assumptions and tests, but treat the response as a proposal, not proof. If the tool’s output is difficult to verify, a simpler manual implementation or a domain expert’s review may be the better choice.

Frequently Asked Questions

Can AI-generated code be used in production?
Yes, when it has passed the same appropriate review, testing, security checks, and release process as other production code. The fact that it was generated should neither exempt it from review nor automatically disqualify it.

Does code that passes tests mean it is safe?
No. Tests cover only the cases they exercise, and a passing result does not establish that requirements are complete or security properties are correct. Combine tests with code review and risk-appropriate analysis.

How can I check whether a generated API call is real?
Verify it in the documentation or source for the exact library and version used by the project, then build and test a small example in that environment. Do not rely solely on an AI-generated explanation.

Should I accept code I cannot understand?
Not without further review. Ask for a smaller change or a clearer explanation, consult documentation, or get help from someone familiar with the code. Understanding the behavior is part of verifying it.

Can I paste company code into an AI tool?
Only if your organization’s policies and the tool’s applicable data-handling terms permit it. Remove credentials and sensitive information, and ask for guidance when the rules are unclear.

Related

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