我试图创建一个os.File的模拟或更具体的io.Reader 。 我想模拟读取128位具体数据而无需实际读取。
用一个uint32就没有问题。
嘲笑:
func (f *FileMock) Read(buf []byte) (n int, err error) { binary.BigEndian.PutUint32(buf, uint32(2052)) return len(buf), nil }测试方法(简化):
b := make([]byte, 128) meta_data := make([]uint32, 4) _, err = s.Read(b) if err != nil { // Handle error } binary.Read(bytes.NewBuffer(b), binary.BigEndian, &meta_data) log.Print(meta_data) // Output [2052 0 0 0]但是当我需要模拟阅读一个uint32切片时, PutUint32并没有什么帮助,因为它从开头写入切片(以前写过数据)。 我尝试了一堆bytes和binary工具的组合,但每次我都无法从字节获取数据时没有运气。 我有最后一次尝试(不是唯一的):
func (f *FileMock) Read(b []byte) (n int, err error) { buf := bytes.NewBuffer(make([]byte, len(b))) err = binary.Write(buf, binary.BigEndian, [4]uint32{2051, 123, 28, 28}) buf.Read(b) return len(b), nil }使用与上述相同的测试方法,我正在获取空片[0, 0, 0, 0] 。 请注意,这是os.File.Read方法的模拟,所以我不能创建一个新的字节片段,而不是它,我需要将我的数据写入现有片段。
起初我想知道如何解决这个问题。 另外我想知道为什么只有[0, 0, 0, 0] ?
感谢您的回答!
I'm trying to create a mock for a os.File or to be more specific io.Reader. I want to emulate reading of 128 bits of concrete data without actual reading.
With a single uint32 there is no problems.
Mock:
func (f *FileMock) Read(buf []byte) (n int, err error) { binary.BigEndian.PutUint32(buf, uint32(2052)) return len(buf), nil }Tested method (simplified):
b := make([]byte, 128) meta_data := make([]uint32, 4) _, err = s.Read(b) if err != nil { // Handle error } binary.Read(bytes.NewBuffer(b), binary.BigEndian, &meta_data) log.Print(meta_data) // Output [2052 0 0 0]But when I need to mock reading of a uint32 slice PutUint32 is not helpful because it writes to a slice from beginning (overrites previously wrtten data). I tried a bunch of combinations of bytesand binary tools but had no luck every time I can't get the data back from bytes. There is my last attempt (it is not the only):
func (f *FileMock) Read(b []byte) (n int, err error) { buf := bytes.NewBuffer(make([]byte, len(b))) err = binary.Write(buf, binary.BigEndian, [4]uint32{2051, 123, 28, 28}) buf.Read(b) return len(b), nil }With the same tested method as described above I'm obtaining an empty slice [0, 0, 0, 0]. Please note, this is a mock for os.File.Read method so I can't create a new slice of bytes instead of it I need to write my data to an existing slice.
At first I'm wondering how to solve the issue. Also I want to know why there is just [0, 0, 0, 0]?
Grateful for answers!
最满意答案
切片共享一个底层数组,你可以写(PutUint32)到buf [4:],buf [8:]等。
Slices share an underlying array, you can write (PutUint32) to buf[4:], buf[8:] etc.
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