golang-stretchr-testify

name	golang-stretchr-testify
description	Comprehensive guide to stretchr/testify for Golang testing. Covers assert, require, mock, and suite packages in depth. Use when writing tests with testify, creating mocks, setting up test suites, or choosing between assert and require. Covers testify assertions, mock expectations, argument matchers, call verification, suite lifecycle, and advanced patterns like Eventually, JSONEq, and custom matchers. Apply when the codebase imports github.com/stretchr/testify.
user-invocable	true
license	MIT
compatibility	Designed for Claude Code or similar AI coding agents, and for projects using Golang.
metadata	{"author":"samber","version":"1.2.3","openclaw":{"emoji":"✅","homepage":"https://github.com/samber/cc-skills-golang","requires":{"bins":["go","gotests"]},"install":[{"kind":"go","package":"github.com/cweill/gotests/...@latest","bins":["gotests"]}],"skill-library-version":"1.11.1"}}
allowed-tools	Read Edit Write Glob Grep Bash(go:*) Bash(golangci-lint:*) Bash(git:*) Agent WebFetch mcp__context7__resolve-library-id mcp__context7__query-docs Bash(gotests:*) AskUserQuestion Bash(godig:*) Bash(gopls:*) LSP mcp__gopls__*

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. Please 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) — prefer it 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:

func TestParseConfig(t *testing.T) {
    is := assert.New(t)
    must := require.New(t)

    cfg, err := ParseConfig("testdata/valid.yaml")
    must.NoError(err)    // stop if parsing fails — cfg would be nil
    must.NotNil(cfg)

    is.Equal("production", cfg.Environment)
    is.Equal(8080, cfg.Port)
    is.True(cfg.TLS.Enabled)
}

Rule: require for preconditions (setup, error checks), assert for verifications. Never mix randomly.

Core Assertions

is := assert.New(t)


is.Equal(expected, actual)              
is.NotEqual(unexpected, actual)
is.EqualValues(expected, actual)        
is.EqualExportedValues(expected, actual)


is.Nil(obj)                  is.NotNil(obj)
is.True(cond)                is.False(cond)
is.Empty(collection)         is.NotEmpty(collection)
is.Len(collection, n)


is.Contains(, )
is.Contains([]{, , }, )
is.Contains([]{: }, )


is.Greater(actual, threshold)     is.Less(actual, ceiling)
is.Positive(val)                  is.Negative(val)
is.Zero(val)


is.Error(err)                     is.NoError(err)
is.ErrorIs(err, ErrNotFound)      
is.ErrorAs(err, &target)
is.ErrorContains(err, )


is.IsType(&User{}, obj)
is.Implements((*io.Reader)(), obj)