1 // Copyright 2020 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package iotest_test 6 7 import ( 8 "errors" 9 "fmt" 10 "testing/iotest" 11 ) 12 13 func ExampleErrReader() { 14 // A reader that always returns a custom error. 15 r := iotest.ErrReader(errors.New("custom error")) 16 n, err := r.Read(nil) 17 fmt.Printf("n: %d\nerr: %q\n", n, err) 18 19 // Output: 20 // n: 0 21 // err: "custom error" 22 } 23