golang-stretchr-testify

1**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.
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3**Modes:**
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5- **Write mode** — adding new tests or mocks to a codebase.
6- **Review mode** — auditing existing test code for testify misuse.
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8# stretchr/testify
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10testify complements Go's `testing` package with readable assertions, mocks, and suites. It does not replace `testing` — always use `*testing.T` as the entry point.
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12This skill is not exhaustive — refer to library documentation and code examples for more information:
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14- 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.
15- To navigate this library's usage in your own code (definitions, call sites, diagnostics), → See `samber/cc-skills-golang@golang-gopls` skill (`gopls`).
16- Context7 remains a fallback for docs not indexed on pkg.go.dev.
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18## assert vs require
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20Both offer identical assertions. The difference is failure behavior:
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22- **assert**: records failure, continues — see all failures at once
23- **require**: calls `t.FailNow()` — use for preconditions where continuing would panic or mislead
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25Use `assert.New(t)` / `require.New(t)` for readability. Name them `is` and `must`:
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27```go
28func TestParseConfig(t *testing.T) {
29    is := assert.New(t)
30    must := require.New(t)
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