github.com/jlowellwofford/u-root@v1.0.0/pkg/testutil/stdin.go (about)

     1  // Copyright 2017 the u-root 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 testutil
     6  
     7  // FakeStdin implements io.Reader and returns predefined list of answers,
     8  // suitable for mocking standard input.
     9  type FakeStdin struct {
    10  	answers    []string
    11  	pos        int
    12  	overflowed bool
    13  }
    14  
    15  // NewFakeStdin creates new FakeStdin value with given answers.
    16  func NewFakeStdin(answers ...string) *FakeStdin {
    17  	var fs = FakeStdin{answers: make([]string, len(answers))}
    18  	for i, a := range answers {
    19  		fs.answers[i] = a + "\n"
    20  	}
    21  	return &fs
    22  }
    23  
    24  // Read answers one by one and keep record whether the stdin
    25  // has overflowed.
    26  func (fs *FakeStdin) Read(p []byte) (int, error) {
    27  	if len(fs.answers) <= fs.pos {
    28  		fs.overflowed = true
    29  		fs.pos = 0
    30  	}
    31  	n := copy(p, fs.answers[fs.pos])
    32  	fs.pos += 1
    33  	return n, nil
    34  }
    35  
    36  // Count returns how many answers have been read.
    37  //
    38  // This counter overflows and never returns value bigger than the count of
    39  // given answers.
    40  func (fs *FakeStdin) Count() int {
    41  	return fs.pos
    42  }
    43  
    44  // Overflowed reports whether more reads happened than expected.
    45  func (fs *FakeStdin) Overflowed() bool {
    46  	return fs.overflowed
    47  }