# Contract Tests vs WireMock Stubs

**Short answer:** Stubs are a code-level description of the responses; contract tests verify the responses against the schema. The first tells the mock what to return; the second proves the real response is valid. They are different stages and both belong in a pipeline.

## What stubs provide

Controlled responses for the tests, so the system can be exercised without the real service. They are authored and can drift.

## What contract tests provide

| Property | Stubs | Contract tests |
| --- | --- | --- |
| Subject | Mock responses | Real responses |
| Authority | Stub code | Schema |
| Catches drift | Not directly | Yes |
| Stage | Isolation | Verification |

## Why the stages matter

A stub lets the system run without the dependency; a contract test proves the dependency still conforms. Replacing one with the other leaves a gap.

## The honest takeaway

Keep the stubs for isolation and the contract checks for conformance. A spec-first studio keeps both tied to the same source.

This is part of the [Powerduck vs WireMock comparison](https://www.powerduck.com/blog/powerduck-vs-wiremock/). Next, read [beyond JVM mocking](https://www.powerduck.com/blog/multi-language-teams-beyond-jvm-mocking/).