Test all possible int64's for variable int encoding/decoding algorithm

testrange.go

type testrange struct {
    start int64
    end   int64
}

func zigzagExhaustiveTest() {
    runtime.GOMAXPROCS(8)

    var wg sync.WaitGroup

    fnRangeTester := func(fnum int, tr testrange, chfailures chan string) {
        fmt.Printf("FN %d STARTED\n", fnum)
        defer wg.Done()
        buf := new(bytes.Buffer)
        for i := tr.start; i != tr.end; i++ {
            buf.Reset()

            in := i
            zzin := varint.ZigzagEncodeUInt64(in)
            err := varint.VarintEncode(buf, zzin)
            if err != nil {
                chfailures <- fmt.Sprintf("Failed on %d: varintEncode err: %v", i, err)
            }

            zzout, err := varint.ReadVarIntToUint(buf)
            if err != nil {
                chfailures <- fmt.Sprintf("Failed on %d: ReadVarIntToUint err: %v", i, err)
            }
            if zzin != zzout {
                chfailures <- fmt.Sprintf("Failed on %d: ReadVarIntToUint zzin != zzout: %d != %d", i, zzin, zzout)
            }

            out := varint.ZigzagDecodeInt64(zzout)
            if in != out {
                chfailures <- fmt.Sprintf("Failed on %d: ReadVarIntToUint in != out: %d != %d", i, in, out)
            }
        }
        fmt.Printf("FN %d is DONE\n", fnum)
    }

    ranges := []testrange{
        {-9223372036854775808, -6917529027641081856},
        {-6917529027641081855, -4611686018427387904},
        {-4611686018427387903, -2305843009213693952},
        {-2305843009213693951, -1},
        {0, 2305843009213693952},
        {2305843009213693953, 4611686018427387904},
        {4611686018427387905, 6917529027641081855},
        {6917529027641081856, 9223372036854775807},
    }
    
    wg.Add(len(ranges))
    failchan := make(chan string, 10)

    for i, trange := range ranges {
        go fnRangeTester(i, trange, failchan)
    }

    go func() {
        wg.Wait()
        close(failchan)
    }()

    // main thread monitors for failures, waiting for the failchan to be closed
    for failmsg := range failchan {
        fmt.Println(failmsg)
    }
    fmt.Println("DONE")
}