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

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.Panics 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.Panics

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:sha256:2ca1a869b386f1a31cb5742666fd37907b7e2511e33907b815bc015ef4d148fc","contract":["assert.Panics returns true and does not record an error when the function panics with a string value","assert.Panics returns true and does not record an error when the function causes a runtime panic","assert.Panics returns false and records an error on the testing receiver when the function does not panic","assert.Panics recovers arbitrary panic values including error objects and integer codes without unhandled termination","assert.Panics formats and includes custom message arguments in the recorded failure when an expected panic does not occur"],"goal":"verify github.com/stretchr/testify/assert.Panics 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.Panics"]},"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.Panics"],"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 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 divide(a, b int) int {
	if b == 0 {
		panic("division by zero")
	}
	return a / b
}

func parseStatus(code int) string {
	if code < 0 {
		panic(errors.New("invalid status code"))
	}
	return "ok"
}

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

	// Example 1: asserting that a function panics with a string message
	panicked := assert.Panics(rep, func() {
		divide(10, 0)
	}, "dividing by zero must panic")

	if panicked {
		fmt.Println("divide(10, 0) panicked as expected.")
	}

	// Example 2: asserting that a function panics with an error instance
	panicked = assert.Panics(rep, func() {
		parseStatus(-1)
	}, "negative status must panic")

	if panicked {
		fmt.Println("parseStatus(-1) panicked as expected.")
	}

	if !rep.failed {
		fmt.Println("All panic assertions succeeded.")
	}
}

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

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.Panics returns true and does not record an error when the function panics with a string value
	{
		t := &contractTestingT{}
		didPanic := assert.Panics(t, func() {
			panic("explicit string panic")
		})
		if !didPanic || t.failed || len(t.errors) != 0 {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: assert.Panics should return true on string panic\n")
			os.Exit(1)
		}
	}

	// Assertion 2: assert.Panics returns true and does not record an error when the function causes a runtime panic
	{
		t := &contractTestingT{}
		didPanic := assert.Panics(t, func() {
			var slice []int
			_ = slice[1]
		})
		if !didPanic || t.failed || len(t.errors) != 0 {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: assert.Panics should return true on runtime panic\n")
			os.Exit(1)
		}
	}

	// Assertion 3: assert.Panics returns false and records an error on the testing receiver when the function does not panic
	{
		t := &contractTestingT{}
		didPanic := assert.Panics(t, func() {
			_ = 1 + 1
		})
		if didPanic || !t.failed || len(t.errors) == 0 {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: assert.Panics should return false and record error when func does not panic\n")
			os.Exit(1)
		}
	}

	// Assertion 4: assert.Panics recovers arbitrary panic values including error objects and integer codes without unhandled termination
	{
		tErr := &contractTestingT{}
		didPanicErr := assert.Panics(tErr, func() {
			panic(errors.New("custom error panic"))
		})
		if !didPanicErr || tErr.failed || len(tErr.errors) != 0 {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: assert.Panics should succeed with error object panic\n")
			os.Exit(1)
		}

		tInt := &contractTestingT{}
		didPanicInt := assert.Panics(tInt, func() {
			panic(404)
		})
		if !didPanicInt || tInt.failed || len(tInt.errors) != 0 {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: assert.Panics should succeed with integer panic\n")
			os.Exit(1)
		}
	}

	// Assertion 5: assert.Panics formats and includes custom message arguments in the recorded failure when an expected panic does not occur
	{
		t := &contractTestingT{}
		marker := "contract_expected_failure_marker"
		didPanic := assert.Panics(t, func() {
			// no panic
		}, "panic should have occurred: %s", marker)
		if didPanic || !t.failed || len(t.errors) == 0 {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: assert.Panics should record error on no panic\n")
			os.Exit(1)
		}
		foundMarker := false
		for _, err := range t.errors {
			if strings.Contains(err, marker) {
				foundMarker = true
				break
			}
		}
		if !foundMarker {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: custom message marker not found in recorded error messages\n")
			os.Exit(1)
		}
	}

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