github.com/stretchr/testify v1.3.0: assert.Contains, assert.NotContains

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify pkg:golang/github.com/stretchr/testify@v1.3.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/stretchr/testify@v1.3.0
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

package sample_test

import (
	"fmt"
	"strings"
	"testing"

	"github.com/stretchr/testify/assert"
)

type mockTestingT struct {
	failed  bool
	message string
}

func (m *mockTestingT) Errorf(format string, args ...interface{}) {
	m.failed = true
	m.message = fmt.Sprintf(format, args...)
}

func TestContainsString(t *testing.T) {
	// assert.Contains returns true and records no error when substring is present
	mock := &mockTestingT{}
	res := assert.Contains(mock, "hello world", "world")
	if !res || mock.failed {
		t.Fatalf("expected true with no failure, got res=%v failed=%v", res, mock.failed)
	}

	// assert.Contains returns false and records error when substring is absent
	mock = &mockTestingT{}
	res = assert.Contains(mock, "hello world", "goodbye")
	if res || !mock.failed {
		t.Fatalf("expected false with failure, got res=%v failed=%v", res, mock.failed)
	}
	if !strings.Contains(mock.message, "does not contain") {
		t.Fatalf("expected failure message to mention 'does not contain', got: %s", mock.message)
	}
}

func TestContainsSliceAndArray(t *testing.T) {
	// assert.Contains returns true when slice contains element
	mock := &mockTestingT{}
	res := assert.Contains(mock, []int{10, 20, 30}, 20)
	if !res || mock.failed {
		t.Fatalf("expected true for slice element, got res=%v failed=%v", res, mock.failed)
	}

	// assert.Contains returns false when slice does not contain element
	mock = &mockTestingT{}
	res = assert.Contains(mock, []int{10, 20, 30}, 99)
	if res || !mock.failed {
		t.Fatalf("expected false for missing slice element, got res=%v failed=%v", res, mock.failed)
	}

	// Array support
	mock = &mockTestingT{}
	arr := [3]string{"apple", "banana", "cherry"}
	res = assert.Contains(mock, arr, "banana")
	if !res || mock.failed {
		t.Fatalf("expected true for array element, got res=%v failed=%v", res, mock.failed)
	}
}

func TestContainsMap(t *testing.T) {
	mock := &mockTestingT{}
	m := map[string]int{"key1": 100, "key2": 200}

	// assert.Contains returns true when map contains the key
	res := assert.Contains(mock, m, "key1")
	if !res || mock.failed {
		t.Fatalf("expected true for map key, got res=%v failed=%v", res, mock.failed)
	}

	// assert.Contains returns false when map does not contain key
	mock = &mockTestingT{}
	res = assert.Contains(mock, m, "key3")
	if res || !mock.failed {
		t.Fatalf("expected false for missing map key, got res=%v failed=%v", res, mock.failed)
	}
}

func TestContainsUnsupportedTypes(t *testing.T) {
	// assert.Contains returns false and records error on nil collection
	mock := &mockTestingT{}
	res := assert.Contains(mock, nil, "item")
	if res || !mock.failed {
		t.Fatalf("expected false and failure on nil, got res=%v failed=%v", res, mock.failed)
	}

	// assert.Contains returns false and records error on non-collection type (int)
	mock = &mockTestingT{}
	res = assert.Contains(mock, 12345, "item")
	if res || !mock.failed {
		t.Fatalf("expected false and failure on integer, got res=%v failed=%v", res, mock.failed)
	}
}

func TestNotContains(t *testing.T) {
	// assert.NotContains returns true when element is absent
	mock := &mockTestingT{}
	res := assert.NotContains(mock, "hello world", "earth")
	if !res || mock.failed {
		t.Fatalf("expected true for absent substring, got res=%v failed=%v", res, mock.failed)
	}

	res = assert.NotContains(mock, []string{"red", "green"}, "blue")
	if !res || mock.failed {
		t.Fatalf("expected true for absent slice element, got res=%v failed=%v", res, mock.failed)
	}

	res = assert.NotContains(mock, map[string]int{"a": 1}, "b")
	if !res || mock.failed {
		t.Fatalf("expected true for absent map key, got res=%v failed=%v", res, mock.failed)
	}

	// assert.NotContains returns false when element is present
	mock = &mockTestingT{}
	res = assert.NotContains(mock, "hello world", "world")
	if res || !mock.failed {
		t.Fatalf("expected false for present substring, got res=%v failed=%v", res, mock.failed)
	}
	if !strings.Contains(mock.message, "should not contain") {
		t.Fatalf("expected failure message to mention 'should not contain', got: %s", mock.message)
	}
}

func TestCustomMessageFormatting(t *testing.T) {
	mock := &mockTestingT{}
	assert.Contains(mock, "abc", "xyz", "check value %s id %d", "probe", 7)
	if !mock.failed {
		t.Fatal("expected mock failure")
	}
	if !strings.Contains(mock.message, "check value probe id 7") {
		t.Fatalf("expected custom message in output, got: %s", mock.message)
	}
}

func TestDirectAssertionsOnTestingT(t *testing.T) {
	// Verify direct invocation with *testing.T
	assert.Contains(t, "testify assertions", "testify")
	assert.Contains(t, []int{1, 2, 3}, 2)
	assert.Contains(t, map[string]string{"env": "production"}, "env")
	assert.NotContains(t, "testify assertions", "missing")
	assert.NotContains(t, []int{1, 2, 3}, 4)
	assert.NotContains(t, map[string]string{"env": "production"}, "staging")
}

{"case":{"caseId":"case:sha256:5ab55c155e56065d857b459902619364d897c2ea5f34997fb7d2d11a4e157495","contract":["assert.Contains returns true and records no error when a substring is found in a string","assert.Contains returns false and records an error when a substring is missing from a string","assert.Contains returns true when a slice or array contains the specified element and false when missing","assert.Contains returns true when a map contains the specified key and false when key is absent","assert.Contains returns false and records an error when called on an unsupported or nil collection type","assert.NotContains returns true when a target substring, slice element, or map key is absent and false when present","assert.Contains formats and includes custom message arguments when an assertion fails"],"goal":"verify pkg:golang/github.com/stretchr/testify@v1.3.0","kind":"HOW","packages":["pkg:golang/github.com/stretchr/testify@v1.3.0"],"schemaVersion":1,"symbols":["github.com/stretchr/testify/assert.Contains","github.com/stretchr/testify/assert.NotContains"]},"contractCommand":["go","test","-v","./..."],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/stretchr/testify@v1.3.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/stretchr/testify@v1.3.0","symbols":["github.com/stretchr/testify/assert.Contains","github.com/stretchr/testify/assert.NotContains"],"verifierAdapter":"golang@1"}

module sample

go 1.22

require github.com/stretchr/testify v1.3.0

require (
	github.com/davecgh/go-spew v1.1.0 // indirect
	github.com/pmezard/go-difflib v1.0.0 // indirect
)

github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/github.com/stretchr/testify@v1.3.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/stretchr/testify@v1.3.0"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}