Testing Exit, Fatal, and Panic in Golang 1/3

Test_exit_fatal_panic_1.go

package main

import (
	"bytes"
	"fmt"
	"os"
	"testing"
)

func TestExit(t *testing.T) {
	// Save the original os.Exit
	originalExit := os.Exit
	defer func() { os.Exit = originalExit }()

	exitCalled := false
	exitCode := 0

	// Mock os.Exit
	os.Exit = func(code int) {
		exitCalled = true
		exitCode = code
		panic("os.Exit called") // Prevent actual exit
	}

	// Capture stdout
	var buf bytes.Buffer
	originalStdout := os.Stdout
	r, w, _ := os.Pipe()
	os.Stdout = w
	defer func() { os.Stdout = originalStdout }()

	// Test the function
	func() {
		defer func() {
			recover() // Catch panic
			w.Close()
		}()
		logAndExit("Critical error occurred")
	}()

	// Read output
	io.Copy(&buf, r)

	// Verify exit behavior
	if !exitCalled {
		t.Errorf("os.Exit was not called")
	}
	if exitCode != 1 {
		t.Errorf("Expected exit code 1, got %d", exitCode)
	}
	if buf.String() != "Critical error occurred\n" {
		t.Errorf("Unexpected output: %s", buf.String())
	}
}

func logAndExit(message string) {
	fmt.Println(message)
	os.Exit(1)
}