How do you choose between unit, slice, integration, and end-to-end tests in Spring?

Selects the smallest Spring test scope that can prove the risky boundary without mocking away framework or infrastructure behavior.

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TL;DR

I use a plain unit test for business logic that can run without Spring. A test slice loads one framework area, such as MVC or JPA, when mapping or configuration is part of the risk. A Spring integration test loads the relevant application context and real adapters, while an end-to-end test crosses the deployed or near-deployed boundary. I choose the smallest scope that can fail for the defect I care about.

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Test scope, feedback speed, framework configuration, real dependencies, contract risk, and complementary coverage.

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Core answer
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Overview
The annotation follows the behavior being proved; @SpringBootTest is not a default synonym for test.
I use a plain unit test for business logic that can run without Spring. A test slice loads one framework area, such as MVC or JPA, when mapping or configuration is part of the risk. A Spring integration test loads the relevant application context and real adapters, while an end-to-end test crosses the deployed or near-deployed boundary. I choose the smallest scope that can fail for the defect I care about.
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Stronger answer
Optional upgrade with examples, trade-offs, and sharper phrasing.
A mocked repository cannot prove SQL, transactions, migrations, or constraints, and a controller unit test cannot prove JSON binding or the security filter chain. Conversely, loading the whole application to test one calculation slows feedback and obscures the reason for failure. I keep many focused unit tests, targeted slices for framework contracts, and a smaller set of real-infrastructure and critical-flow tests. Test names state the behavior and boundary, not the annotation.

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Using SpringBootTest for every class.
Mocking the exact behavior the test claims to prove.
Treating end-to-end tests as the only valuable tests.

How do you choose between unit, slice, integration, and end-to-end tests in Spring?

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