golangy
Assertions, mocking, and test tooling beyond the standard library.
testify
Assertions and mocks for the standard testing package — the most common reason a Go test file has more than one import.
go.uber.org/mock
Interface mocking via code generation, maintained by Uber after the original golang/mock was archived.
Ginkgo
A BDD-style testing framework with its own runner — a real departure from table-driven tests, worth it mainly for large suites that want structure.