// Package assert provides programmer-error checks that abort the process.
//
// An assertion failure is never a user error: it means the program reached a
// state its author believed impossible. User errors are returned as values.
package assert

import "fmt"

// True aborts unless cond holds.
func True(cond bool, format string, args ...any) {
	if !cond {
		panic("assertion failed: " + fmt.Sprintf(format, args...))
	}
}

// Equal aborts unless got == want.
func Equal[T comparable](got, want T, format string, args ...any) {
	if got != want {
		panic(fmt.Sprintf("assertion failed: %s: got %v, want %v",
			fmt.Sprintf(format, args...), got, want))
	}
}

// NoError aborts if err is non-nil. Use only where an error is structurally
// impossible, never to discard an error a caller could handle.
func NoError(err error, format string, args ...any) {
	if err != nil {
		panic(fmt.Sprintf("assertion failed: %s: %v",
			fmt.Sprintf(format, args...), err))
	}
}

// Unreachable aborts unconditionally.
func Unreachable(format string, args ...any) {
	panic("unreachable: " + fmt.Sprintf(format, args...))
}