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

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.NoError 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.NoError

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:d9346c2b2613a2f2f90620755c8f8a858ba2ae67186b3f257c9f5145e4fa686b","contract":["assert.NoError returns true and records no error when err is nil","assert.NoError returns false and records an error when err is a non-nil error","assert.NoError formats and includes custom message arguments when an error is present","assert.NoError returns true without formatting or recording errors when nil is passed with custom messages"],"goal":"verify github.com/stretchr/testify/assert.NoError 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.NoError"]},"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.NoError"],"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 (
	"errors"
	"fmt"

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

// Reporter implements assert.TestingT to capture test assertion state.
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 divide(a, b int) (int, error) {
	if b == 0 {
		return 0, errors.New("cannot divide by zero")
	}
	return a / b, nil
}

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

	// Example 1: Successful operation returning nil error
	result, err := divide(10, 2)
	if assert.NoError(reporter, err, "dividing 10 by 2 should not fail") {
		fmt.Printf("Division succeeded: result = %d\n", result)
	}

	// Example 2: Handling a function that returns an error
	_, errZero := divide(10, 0)
	failedReporter := &Reporter{}
	if !assert.NoError(failedReporter, errZero, "dividing by zero returns error") {
		fmt.Println("Correctly detected division by zero error.")
	}

	if !reporter.failed {
		fmt.Println("All assert.NoError checks passed.")
	}
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/stretchr/testify/assert.NoError 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.NoError"
  ]
}

package main

import (
	"errors"
	"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...))
}

func main() {
	// Assertion 1: assert.NoError returns true and records no error when err is nil
	{
		t := &contractTestingT{}
		var err error = nil
		ok := assert.NoError(t, err)
		if !ok || t.failed || len(t.errors) != 0 {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: NoError should return true with no errors when err is nil\n")
			os.Exit(1)
		}
	}

	// Assertion 2: assert.NoError returns false and records an error when err is a non-nil error
	{
		t := &contractTestingT{}
		err := errors.New("sample error occurred")
		ok := assert.NoError(t, err)
		if ok || !t.failed || len(t.errors) == 0 {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: NoError should return false and record error when err is non-nil\n")
			os.Exit(1)
		}
		if !strings.Contains(t.errors[0], "sample error occurred") {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: error message should contain original error text\n")
			os.Exit(1)
		}
	}

	// Assertion 3: assert.NoError formats and includes custom message arguments when an error is present
	{
		t := &contractTestingT{}
		err := errors.New("network failure")
		ok := assert.NoError(t, err, "request failed for code %d", 404)
		if ok || !t.failed || len(t.errors) == 0 {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: NoError should return false when error present with custom message\n")
			os.Exit(1)
		}
		joinedErrors := strings.Join(t.errors, " ")
		if !strings.Contains(joinedErrors, "request failed for code 404") {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: error output should include formatted custom message\n")
			os.Exit(1)
		}
	}

	// Assertion 4: assert.NoError returns true without formatting or recording errors when nil is passed with custom messages
	{
		t := &contractTestingT{}
		ok := assert.NoError(t, nil, "custom message %s", "should not appear")
		if !ok || t.failed || len(t.errors) != 0 {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: NoError should return true and record no error with custom messages on nil\n")
			os.Exit(1)
		}
	}

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