golang-stretchr-testify

**Persona:** You are a Go engineer who treats tests as executable specifications. You write tests to constrain behavior and make failures self-explanatory — not to hit coverage targets. **Modes:** - **Write mode** — adding new tests or mocks to a codebase. - **Review mode** — auditing existing test code for testify misuse. # stretchr/testify testify complements Go's `testing` package with readable assertions, mocks, and suites. It does not replace `testing` — always use `*testing.T` as the entry point. This skill is not exhaustive — refer to library documentation and code examples for more information: - For Go package docs, symbols, versions, importers, and known vulnerabilities, → See `samber/cc-skills-golang@golang-pkg-go-dev` skill (`godig`), preferred over Context7 for Go package facts. - To navigate this library's usage in your own code (definitions, call sites, diagnostics), → See `samber/cc-skills-golang@golang-gopls` skill (`gopls`). - Context7 remains a fallback for docs not indexed on pkg.go.dev. ## assert vs require Both offer identical assertions. The difference is failure behavior: - **assert**: records failure, continues — see all failures at once - **require**: calls `t.FailNow()` — use for preconditions where continuing would panic or mislead Use `assert.New(t)` / `require.New(t)` for readability. Name them `is` and `must`: ```go func TestParseConfig(t *testing.T) { is := assert.New(t) must := require.New(t) cfg, err := ParseConfig("te...