lbcd/blockchain/mediantime_test.go

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// Copyright (c) 2013-2017 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package blockchain
import (
"strconv"
"testing"
"time"
)
// TestMedianTime tests the medianTime implementation.
func TestMedianTime(t *testing.T) {
tests := []struct {
in []int64
wantOffset int64
useDupID bool
}{
// Not enough samples must result in an offset of 0.
{in: []int64{1}, wantOffset: 0},
{in: []int64{1, 2}, wantOffset: 0},
{in: []int64{1, 2, 3}, wantOffset: 0},
{in: []int64{1, 2, 3, 4}, wantOffset: 0},
// Various number of entries. The expected offset is only
// updated on odd number of elements.
{in: []int64{-13, 57, -4, -23, -12}, wantOffset: -12},
{in: []int64{55, -13, 61, -52, 39, 55}, wantOffset: 39},
{in: []int64{-62, -58, -30, -62, 51, -30, 15}, wantOffset: -30},
{in: []int64{29, -47, 39, 54, 42, 41, 8, -33}, wantOffset: 39},
{in: []int64{37, 54, 9, -21, -56, -36, 5, -11, -39}, wantOffset: -11},
{in: []int64{57, -28, 25, -39, 9, 63, -16, 19, -60, 25}, wantOffset: 9},
{in: []int64{-5, -4, -3, -2, -1}, wantOffset: -3, useDupID: true},
// The offset stops being updated once the max number of entries
// has been reached. This is actually a bug from Bitcoin Core,
// but since the time is ultimately used as a part of the
// consensus rules, it must be mirrored.
{in: []int64{-67, 67, -50, 24, 63, 17, 58, -14, 5, -32, -52}, wantOffset: 17},
{in: []int64{-67, 67, -50, 24, 63, 17, 58, -14, 5, -32, -52, 45}, wantOffset: 17},
{in: []int64{-67, 67, -50, 24, 63, 17, 58, -14, 5, -32, -52, 45, 4}, wantOffset: 17},
// Offsets that are too far away from the local time should
// be ignored.
{in: []int64{-4201, 4202, -4203, 4204, -4205}, wantOffset: 0},
// Excerise the condition where the median offset is greater
// than the max allowed adjustment, but there is at least one
// sample that is close enough to the current time to avoid
// triggering a warning about an invalid local clock.
{in: []int64{4201, 4202, 4203, 4204, -299}, wantOffset: 0},
}
// Modify the max number of allowed median time entries for these tests.
maxMedianTimeEntries = 10
defer func() { maxMedianTimeEntries = 200 }()
for i, test := range tests {
filter := NewMedianTime()
for j, offset := range test.in {
id := strconv.Itoa(j)
now := time.Unix(time.Now().Unix(), 0)
tOffset := now.Add(time.Duration(offset) * time.Second)
filter.AddTimeSample(id, tOffset)
// Ensure the duplicate IDs are ignored.
if test.useDupID {
// Modify the offsets to ensure the final median
// would be different if the duplicate is added.
tOffset = tOffset.Add(time.Duration(offset) *
time.Second)
filter.AddTimeSample(id, tOffset)
}
}
// Since it is possible that the time.Now call in AddTimeSample
// and the time.Now calls here in the tests will be off by one
// second, allow a fudge factor to compensate.
gotOffset := filter.Offset()
wantOffset := time.Duration(test.wantOffset) * time.Second
wantOffset2 := time.Duration(test.wantOffset-1) * time.Second
if gotOffset != wantOffset && gotOffset != wantOffset2 {
t.Errorf("Offset #%d: unexpected offset -- got %v, "+
"want %v or %v", i, gotOffset, wantOffset,
wantOffset2)
continue
}
// Since it is possible that the time.Now call in AdjustedTime
// and the time.Now call here in the tests will be off by one
// second, allow a fudge factor to compensate.
adjustedTime := filter.AdjustedTime()
now := time.Unix(time.Now().Unix(), 0)
wantTime := now.Add(filter.Offset())
wantTime2 := now.Add(filter.Offset() - time.Second)
if !adjustedTime.Equal(wantTime) && !adjustedTime.Equal(wantTime2) {
t.Errorf("AdjustedTime #%d: unexpected result -- got %v, "+
"want %v or %v", i, adjustedTime, wantTime,
wantTime2)
continue
}
}
}