github.com/stretchr/testify v1.3.0: assert.Nil

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 github.com/stretchr/testify/assert.Nil in 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
Demonstrate these symbols/APIs:
  - github.com/stretchr/testify/assert.Nil

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.

{"case":{"caseId":"case:sha256:a9c2ae042b8081427e0c21ab81ed087c92af0a045e2db616fc63a8c94bd5e020","contract":["assert.Nil returns true and records no error for untyped nil","assert.Nil returns true and records no error for typed nil pointers, slices, maps, channels, and funcs","assert.Nil returns false and records an error when the value is a non-nil basic type or struct","assert.Nil returns false and records an error when the value is an allocated non-nil pointer, slice, map, or channel","assert.Nil formats user-provided custom failure message when the assertion fails"],"goal":"verify github.com/stretchr/testify/assert.Nil in 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.Nil"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","packageManagerVersion":"1.26.6","runtime":"go","runtimeVersion":"1.26.6","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.Nil"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

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=

package main

import (
	"fmt"

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

// Reporter implements assert.TestingT to record assertion outcomes.
type Reporter struct {
	errors []string
	failed bool
}

func (r *Reporter) Errorf(format string, args ...interface{}) {
	r.failed = true
	r.errors = append(r.errors, fmt.Sprintf(format, args...))
}

func main() {
	reporter := &Reporter{}

	// Example 1: Verifying untyped nil
	if assert.Nil(reporter, nil) {
		fmt.Println("Untyped nil verified successfully.")
	}

	// Example 2: Verifying typed nil pointer and slice
	var ptr *int = nil
	var slice []string = nil
	if assert.Nil(reporter, ptr) && assert.Nil(reporter, slice) {
		fmt.Println("Typed nil pointer and slice verified successfully.")
	}

	// Example 3: Verifying typed nil map, channel, and function
	var m map[string]int = nil
	var ch chan int = nil
	var fn func() = nil
	if assert.Nil(reporter, m) && assert.Nil(reporter, ch) && assert.Nil(reporter, fn) {
		fmt.Println("Typed nil map, channel, and function verified successfully.")
	}

	if !reporter.failed {
		fmt.Println("All assert.Nil demonstrations completed without errors.")
	}
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/stretchr/testify/assert.Nil in pkg:golang/github.com/stretchr/testify@v1.3.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/stretchr/testify@v1.3.0"
  ],
  "symbols": [
    "github.com/stretchr/testify/assert.Nil"
  ]
}

package main

import (
	"fmt"
	"os"
	"strings"

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

type contractTestingT struct {
	errors []string
	failed bool
}

func (t *contractTestingT) Errorf(format string, args ...interface{}) {
	t.failed = true
	t.errors = append(t.errors, fmt.Sprintf(format, args...))
}

type sampleItem struct {
	ID   int
	Name string
}

func main() {
	// Assertion 1: assert.Nil returns true and records no error for untyped nil
	{
		t := &contractTestingT{}
		if !assert.Nil(t, nil) || t.failed || len(t.errors) != 0 {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: untyped nil should be nil\n")
			os.Exit(1)
		}
	}

	// Assertion 2: assert.Nil returns true and records no error for typed nil pointers, slices, maps, channels, and funcs
	{
		t := &contractTestingT{}
		var nilPtr *int
		var nilSlice []string
		var nilMap map[string]int
		var nilChan chan int
		var nilFunc func()

		if !assert.Nil(t, nilPtr) || t.failed || len(t.errors) != 0 {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: nil pointer should be nil\n")
			os.Exit(1)
		}
		if !assert.Nil(t, nilSlice) || t.failed || len(t.errors) != 0 {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: nil slice should be nil\n")
			os.Exit(1)
		}
		if !assert.Nil(t, nilMap) || t.failed || len(t.errors) != 0 {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: nil map should be nil\n")
			os.Exit(1)
		}
		if !assert.Nil(t, nilChan) || t.failed || len(t.errors) != 0 {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: nil chan should be nil\n")
			os.Exit(1)
		}
		if !assert.Nil(t, nilFunc) || t.failed || len(t.errors) != 0 {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: nil func should be nil\n")
			os.Exit(1)
		}
	}

	// Assertion 3: assert.Nil returns false and records an error when the value is a non-nil basic type or struct
	{
		tInt := &contractTestingT{}
		if assert.Nil(tInt, 42) || !tInt.failed || len(tInt.errors) == 0 {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: non-zero int should not be nil\n")
			os.Exit(1)
		}

		tZero := &contractTestingT{}
		if assert.Nil(tZero, 0) || !tZero.failed || len(tZero.errors) == 0 {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: zero int should not be nil\n")
			os.Exit(1)
		}

		tStr := &contractTestingT{}
		if assert.Nil(tStr, "example") || !tStr.failed || len(tStr.errors) == 0 {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: string should not be nil\n")
			os.Exit(1)
		}

		tStruct := &contractTestingT{}
		if assert.Nil(tStruct, sampleItem{ID: 1, Name: "alpha"}) || !tStruct.failed || len(tStruct.errors) == 0 {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: struct should not be nil\n")
			os.Exit(1)
		}
	}

	// Assertion 4: assert.Nil returns false and records an error when the value is an allocated non-nil pointer, slice, map, or channel
	{
		val := 10
		tPtr := &contractTestingT{}
		if assert.Nil(tPtr, &val) || !tPtr.failed || len(tPtr.errors) == 0 {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: allocated pointer should not be nil\n")
			os.Exit(1)
		}

		tSlice := &contractTestingT{}
		if assert.Nil(tSlice, []int{}) || !tSlice.failed || len(tSlice.errors) == 0 {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: empty allocated slice should not be nil\n")
			os.Exit(1)
		}

		tMap := &contractTestingT{}
		if assert.Nil(tMap, make(map[string]int)) || !tMap.failed || len(tMap.errors) == 0 {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: empty allocated map should not be nil\n")
			os.Exit(1)
		}

		tChan := &contractTestingT{}
		if assert.Nil(tChan, make(chan int)) || !tChan.failed || len(tChan.errors) == 0 {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: allocated chan should not be nil\n")
			os.Exit(1)
		}
	}

	// Assertion 5: assert.Nil formats user-provided custom failure message when the assertion fails
	{
		t := &contractTestingT{}
		customDetail := "resource initialization expected nil"
		if assert.Nil(t, "not-nil", "assertion failure: %s", customDetail) || !t.failed || len(t.errors) == 0 {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: assert.Nil should return false on non-nil string\n")
			os.Exit(1)
		}

		foundMessage := false
		for _, errMsg := range t.errors {
			if strings.Contains(errMsg, "assertion failure: resource initialization expected nil") {
				foundMessage = true
				break
			}
		}
		if !foundMessage {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: error message did not contain expected formatted text\n")
			os.Exit(1)
		}
	}

	fmt.Println("All contract assertions passed successfully.")
}