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Compare two io.Readers
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| package io | |
| // Copyright (c) 2016 Phill Sparks | |
| // License MIT | |
| import ( | |
| "bytes" | |
| "fmt" | |
| "io" | |
| ) | |
| const chunkSize = 1024 | |
| // CompareReaders takes two io.Reader and compares them, byte for byte, | |
| // returning true if they're identical. | |
| func CompareReaders(a, b io.Reader) bool { | |
| chunkA := make([]byte, chunkSize) | |
| chunkB := make([]byte, chunkSize) | |
| for { | |
| readA, errA := a.Read(chunkA) | |
| readB, errB := b.Read(chunkB) | |
| if readA != readB { | |
| return false | |
| } | |
| if bytes.Compare(chunkA[:readA], chunkB[:readB]) != 0 { | |
| return false | |
| } | |
| if errA != errB { | |
| return false | |
| } | |
| if errA == io.EOF || errB == io.EOF { | |
| break | |
| } | |
| } | |
| return true | |
| } |
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| package io | |
| // Copyright (c) 2016 Phill Sparks | |
| // License MIT | |
| import ( | |
| "bytes" | |
| "io" | |
| "testing" | |
| ) | |
| func TestCompareReaders(t *testing.T) { | |
| a := bytes.NewReader([]byte{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k'}) | |
| b := bytes.NewReader([]byte{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k'}) | |
| if !CompareReaders(a, b) { | |
| t.Error("Identical readers not matching") | |
| } | |
| a.Seek(0, io.SeekStart) | |
| c := bytes.NewReader([]byte{'a', 'b', 'c'}) | |
| if CompareReaders(a, c) { | |
| t.Error("First reader is longer than second, should not match") | |
| } | |
| a.Seek(0, io.SeekStart) | |
| c.Seek(0, io.SeekStart) | |
| if CompareReaders(c, a) { | |
| t.Error("First reader is shorter than second, should not match") | |
| } | |
| a.Seek(0, io.SeekStart) | |
| d := bytes.NewReader([]byte{'z', 'y', 'x', 'w', 'v', 'u', 't', 's', 'r', 'q', 'p'}) | |
| if CompareReaders(a, d) { | |
| t.Error("Readers with different content should not match") | |
| } | |
| } |
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