kaspad/blockdag/reachability_test.go
stasatdaglabs 51ff9e2562
[NOD-571] Cover ghostdag in tests where possible (#613)
* [NOD-571] Cover reachabilityInterval split methods.

* [NOD-571] Cover reindexInterval.

* [NOD-571] Cover reachability String() methods.

* [NOD-571] Cover blueAnticoneSize.

* [NOD-571] Remove unnecessary error from setTreeNode.

* [NOD-571] Add TestGHOSTDAGErrors.

* [NOD-571] Use PrepareBlockForTest in TestBlueAnticoneSizeErrors.

* [NOD-571] Use PrepareBlockForTest in TestGHOSTDAGErrors.

* [NOD-571] Add substring checks to TestSplitFractionErrors.

* [NOD-571] Add substring checks to TestSplitExactErrors and TestSplitWithExponentialBiasErrors.

* [NOD-571] Add comments to TestReindexIntervalErrors.

* [NOD-571] Add additional info in some error messages.

* [NOD-571] Fix error messages.
2020-02-09 11:27:10 +02:00

649 lines
22 KiB
Go

package blockdag
import (
"reflect"
"strings"
"testing"
)
func TestAddChild(t *testing.T) {
// Scenario 1: test addChild in a chain
// root -> a -> b -> c...
// Create the root node of a new reachability tree
root := newReachabilityTreeNode(&blockNode{})
root.setInterval(newReachabilityInterval(1, 100))
// Add a chain of child nodes just before a reindex occurs (2^6=64 < 100)
currentTip := root
for i := 0; i < 6; i++ {
node := newReachabilityTreeNode(&blockNode{})
modifiedNodes, err := currentTip.addChild(node)
if err != nil {
t.Fatalf("TestAddChild: addChild failed: %s", err)
}
// Expect only the node and its parent to be affected
expectedModifiedNodes := []*reachabilityTreeNode{currentTip, node}
if !reflect.DeepEqual(modifiedNodes, expectedModifiedNodes) {
t.Fatalf("TestAddChild: unexpected modifiedNodes. "+
"want: %s, got: %s", expectedModifiedNodes, modifiedNodes)
}
currentTip = node
}
// Add another node to the tip of the chain to trigger a reindex (100 < 2^7=128)
lastChild := newReachabilityTreeNode(&blockNode{})
modifiedNodes, err := currentTip.addChild(lastChild)
if err != nil {
t.Fatalf("TestAddChild: addChild failed: %s", err)
}
// Expect more than just the node and its parent to be modified but not
// all the nodes
if len(modifiedNodes) <= 2 && len(modifiedNodes) >= 7 {
t.Fatalf("TestAddChild: unexpected amount of modifiedNodes.")
}
// Expect the tip to have an interval of 1 and remaining interval of 0
tipInterval := lastChild.interval.size()
if tipInterval != 1 {
t.Fatalf("TestAddChild: unexpected tip interval size: want: 1, got: %d", tipInterval)
}
tipRemainingInterval := lastChild.remainingInterval.size()
if tipRemainingInterval != 0 {
t.Fatalf("TestAddChild: unexpected tip interval size: want: 0, got: %d", tipRemainingInterval)
}
// Expect all nodes to be descendant nodes of root
currentNode := currentTip
for currentNode != nil {
if !root.isAncestorOf(currentNode) {
t.Fatalf("TestAddChild: currentNode is not a descendant of root")
}
currentNode = currentNode.parent
}
// Scenario 2: test addChild where all nodes are direct descendants of root
// root -> a, b, c...
// Create the root node of a new reachability tree
root = newReachabilityTreeNode(&blockNode{})
root.setInterval(newReachabilityInterval(1, 100))
// Add child nodes to root just before a reindex occurs (2^6=64 < 100)
childNodes := make([]*reachabilityTreeNode, 6)
for i := 0; i < len(childNodes); i++ {
childNodes[i] = newReachabilityTreeNode(&blockNode{})
modifiedNodes, err := root.addChild(childNodes[i])
if err != nil {
t.Fatalf("TestAddChild: addChild failed: %s", err)
}
// Expect only the node and the root to be affected
expectedModifiedNodes := []*reachabilityTreeNode{root, childNodes[i]}
if !reflect.DeepEqual(modifiedNodes, expectedModifiedNodes) {
t.Fatalf("TestAddChild: unexpected modifiedNodes. "+
"want: %s, got: %s", expectedModifiedNodes, modifiedNodes)
}
}
// Add another node to the root to trigger a reindex (100 < 2^7=128)
lastChild = newReachabilityTreeNode(&blockNode{})
modifiedNodes, err = root.addChild(lastChild)
if err != nil {
t.Fatalf("TestAddChild: addChild failed: %s", err)
}
// Expect more than just the node and the root to be modified but not
// all the nodes
if len(modifiedNodes) <= 2 && len(modifiedNodes) >= 7 {
t.Fatalf("TestAddChild: unexpected amount of modifiedNodes.")
}
// Expect the last-added child to have an interval of 1 and remaining interval of 0
lastChildInterval := lastChild.interval.size()
if lastChildInterval != 1 {
t.Fatalf("TestAddChild: unexpected lastChild interval size: want: 1, got: %d", lastChildInterval)
}
lastChildRemainingInterval := lastChild.remainingInterval.size()
if lastChildRemainingInterval != 0 {
t.Fatalf("TestAddChild: unexpected lastChild interval size: want: 0, got: %d", lastChildRemainingInterval)
}
// Expect all nodes to be descendant nodes of root
for _, childNode := range childNodes {
if !root.isAncestorOf(childNode) {
t.Fatalf("TestAddChild: childNode is not a descendant of root")
}
}
}
func TestSplitFraction(t *testing.T) {
tests := []struct {
interval *reachabilityInterval
fraction float64
expectedLeft *reachabilityInterval
expectedRight *reachabilityInterval
}{
{
interval: newReachabilityInterval(1, 100),
fraction: 0.5,
expectedLeft: newReachabilityInterval(1, 50),
expectedRight: newReachabilityInterval(51, 100),
},
{
interval: newReachabilityInterval(2, 100),
fraction: 0.5,
expectedLeft: newReachabilityInterval(2, 51),
expectedRight: newReachabilityInterval(52, 100),
},
{
interval: newReachabilityInterval(1, 99),
fraction: 0.5,
expectedLeft: newReachabilityInterval(1, 50),
expectedRight: newReachabilityInterval(51, 99),
},
{
interval: newReachabilityInterval(1, 100),
fraction: 0.2,
expectedLeft: newReachabilityInterval(1, 20),
expectedRight: newReachabilityInterval(21, 100),
},
{
interval: newReachabilityInterval(1, 100),
fraction: 0,
expectedLeft: newReachabilityInterval(1, 0),
expectedRight: newReachabilityInterval(1, 100),
},
{
interval: newReachabilityInterval(1, 100),
fraction: 1,
expectedLeft: newReachabilityInterval(1, 100),
expectedRight: newReachabilityInterval(101, 100),
},
}
for i, test := range tests {
left, right, err := test.interval.splitFraction(test.fraction)
if err != nil {
t.Fatalf("TestSplitFraction: splitFraction unexpectedly failed in test #%d: %s", i, err)
}
if !reflect.DeepEqual(left, test.expectedLeft) {
t.Errorf("TestSplitFraction: unexpected left in test #%d. "+
"want: %s, got: %s", i, test.expectedLeft, left)
}
if !reflect.DeepEqual(right, test.expectedRight) {
t.Errorf("TestSplitFraction: unexpected right in test #%d. "+
"want: %s, got: %s", i, test.expectedRight, right)
}
}
}
func TestSplitExact(t *testing.T) {
tests := []struct {
interval *reachabilityInterval
sizes []uint64
expectedIntervals []*reachabilityInterval
}{
{
interval: newReachabilityInterval(1, 100),
sizes: []uint64{100},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 100),
},
},
{
interval: newReachabilityInterval(1, 100),
sizes: []uint64{50, 50},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 50),
newReachabilityInterval(51, 100),
},
},
{
interval: newReachabilityInterval(1, 100),
sizes: []uint64{10, 20, 30, 40},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 10),
newReachabilityInterval(11, 30),
newReachabilityInterval(31, 60),
newReachabilityInterval(61, 100),
},
},
{
interval: newReachabilityInterval(1, 100),
sizes: []uint64{0, 100},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 0),
newReachabilityInterval(1, 100),
},
},
{
interval: newReachabilityInterval(1, 100),
sizes: []uint64{100, 0},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 100),
newReachabilityInterval(101, 100),
},
},
}
for i, test := range tests {
intervals, err := test.interval.splitExact(test.sizes)
if err != nil {
t.Fatalf("TestSplitExact: splitExact unexpectedly failed in test #%d: %s", i, err)
}
if !reflect.DeepEqual(intervals, test.expectedIntervals) {
t.Errorf("TestSplitExact: unexpected intervals in test #%d. "+
"want: %s, got: %s", i, test.expectedIntervals, intervals)
}
}
}
func TestSplitWithExponentialBias(t *testing.T) {
tests := []struct {
interval *reachabilityInterval
sizes []uint64
expectedIntervals []*reachabilityInterval
}{
{
interval: newReachabilityInterval(1, 100),
sizes: []uint64{100},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 100),
},
},
{
interval: newReachabilityInterval(1, 100),
sizes: []uint64{50, 50},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 50),
newReachabilityInterval(51, 100),
},
},
{
interval: newReachabilityInterval(1, 100),
sizes: []uint64{10, 20, 30, 40},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 10),
newReachabilityInterval(11, 30),
newReachabilityInterval(31, 60),
newReachabilityInterval(61, 100),
},
},
{
interval: newReachabilityInterval(1, 100),
sizes: []uint64{25, 25},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 50),
newReachabilityInterval(51, 100),
},
},
{
interval: newReachabilityInterval(1, 100),
sizes: []uint64{1, 1},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 50),
newReachabilityInterval(51, 100),
},
},
{
interval: newReachabilityInterval(1, 100),
sizes: []uint64{33, 33, 33},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 33),
newReachabilityInterval(34, 66),
newReachabilityInterval(67, 100),
},
},
{
interval: newReachabilityInterval(1, 100),
sizes: []uint64{10, 15, 25},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 10),
newReachabilityInterval(11, 25),
newReachabilityInterval(26, 100),
},
},
{
interval: newReachabilityInterval(1, 100),
sizes: []uint64{25, 15, 10},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 75),
newReachabilityInterval(76, 90),
newReachabilityInterval(91, 100),
},
},
{
interval: newReachabilityInterval(1, 10_000),
sizes: []uint64{10, 10, 20},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 20),
newReachabilityInterval(21, 40),
newReachabilityInterval(41, 10_000),
},
},
{
interval: newReachabilityInterval(1, 100_000),
sizes: []uint64{31_000, 31_000, 30_001},
expectedIntervals: []*reachabilityInterval{
newReachabilityInterval(1, 35_000),
newReachabilityInterval(35_001, 69_999),
newReachabilityInterval(70_000, 100_000),
},
},
}
for i, test := range tests {
intervals, err := test.interval.splitWithExponentialBias(test.sizes)
if err != nil {
t.Fatalf("TestSplitWithExponentialBias: splitWithExponentialBias unexpectedly failed in test #%d: %s", i, err)
}
if !reflect.DeepEqual(intervals, test.expectedIntervals) {
t.Errorf("TestSplitWithExponentialBias: unexpected intervals in test #%d. "+
"want: %s, got: %s", i, test.expectedIntervals, intervals)
}
}
}
func TestIsInFuture(t *testing.T) {
blocks := futureCoveringBlockSet{
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(2, 3)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(4, 67)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(67, 77)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(657, 789)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1000, 1000)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1920, 1921)}},
}
tests := []struct {
block *futureCoveringBlock
expectedResult bool
}{
{
block: &futureCoveringBlock{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1, 1)}},
expectedResult: false,
},
{
block: &futureCoveringBlock{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(5, 7)}},
expectedResult: true,
},
{
block: &futureCoveringBlock{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(67, 76)}},
expectedResult: true,
},
{
block: &futureCoveringBlock{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(78, 100)}},
expectedResult: false,
},
{
block: &futureCoveringBlock{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1980, 2000)}},
expectedResult: false,
},
{
block: &futureCoveringBlock{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1920, 1920)}},
expectedResult: true,
},
}
for i, test := range tests {
result := blocks.isInFuture(test.block)
if result != test.expectedResult {
t.Errorf("TestIsInFuture: unexpected result in test #%d. Want: %t, got: %t",
i, test.expectedResult, result)
}
}
}
func TestInsertBlock(t *testing.T) {
blocks := futureCoveringBlockSet{
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1, 3)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(4, 67)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(67, 77)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(657, 789)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1000, 1000)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1920, 1921)}},
}
tests := []struct {
toInsert []*futureCoveringBlock
expectedResult futureCoveringBlockSet
}{
{
toInsert: []*futureCoveringBlock{
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(5, 7)}},
},
expectedResult: futureCoveringBlockSet{
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1, 3)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(4, 67)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(67, 77)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(657, 789)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1000, 1000)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1920, 1921)}},
},
},
{
toInsert: []*futureCoveringBlock{
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(65, 78)}},
},
expectedResult: futureCoveringBlockSet{
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1, 3)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(4, 67)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(65, 78)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(657, 789)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1000, 1000)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1920, 1921)}},
},
},
{
toInsert: []*futureCoveringBlock{
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(88, 97)}},
},
expectedResult: futureCoveringBlockSet{
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1, 3)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(4, 67)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(67, 77)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(88, 97)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(657, 789)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1000, 1000)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1920, 1921)}},
},
},
{
toInsert: []*futureCoveringBlock{
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(88, 97)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(3000, 3010)}},
},
expectedResult: futureCoveringBlockSet{
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1, 3)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(4, 67)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(67, 77)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(88, 97)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(657, 789)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1000, 1000)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(1920, 1921)}},
{treeNode: &reachabilityTreeNode{interval: newReachabilityInterval(3000, 3010)}},
},
},
}
for i, test := range tests {
// Create a clone of blocks so that we have a clean start for every test
blocksClone := make(futureCoveringBlockSet, len(blocks))
for i, block := range blocks {
blocksClone[i] = block
}
for _, block := range test.toInsert {
blocksClone.insertBlock(block)
}
if !reflect.DeepEqual(blocksClone, test.expectedResult) {
t.Errorf("TestInsertBlock: unexpected result in test #%d. Want: %s, got: %s",
i, test.expectedResult, blocksClone)
}
}
}
func TestSplitFractionErrors(t *testing.T) {
interval := newReachabilityInterval(100, 200)
// Negative fraction
_, _, err := interval.splitFraction(-0.5)
if err == nil {
t.Fatalf("TestSplitFractionErrors: splitFraction unexpectedly " +
"didn't return an error for a negative fraction")
}
expectedErrSubstring := "fraction must be between 0 and 1"
if !strings.Contains(err.Error(), expectedErrSubstring) {
t.Fatalf("TestSplitFractionErrors: splitFraction returned wrong error "+
"for a negative fraction. "+
"Want: %s, got: %s", expectedErrSubstring, err)
}
// Fraction > 1
_, _, err = interval.splitFraction(1.5)
if err == nil {
t.Fatalf("TestSplitFractionErrors: splitFraction unexpectedly " +
"didn't return an error for a fraction greater than 1")
}
expectedErrSubstring = "fraction must be between 0 and 1"
if !strings.Contains(err.Error(), expectedErrSubstring) {
t.Fatalf("TestSplitFractionErrors: splitFraction returned wrong error "+
"for a fraction greater than 1. "+
"Want: %s, got: %s", expectedErrSubstring, err)
}
// Splitting an empty interval
emptyInterval := newReachabilityInterval(1, 0)
_, _, err = emptyInterval.splitFraction(0.5)
if err == nil {
t.Fatalf("TestSplitFractionErrors: splitFraction unexpectedly " +
"didn't return an error for an empty interval")
}
expectedErrSubstring = "cannot split an empty interval"
if !strings.Contains(err.Error(), expectedErrSubstring) {
t.Fatalf("TestSplitFractionErrors: splitFraction returned wrong error "+
"for an empty interval. "+
"Want: %s, got: %s", expectedErrSubstring, err)
}
}
func TestSplitExactErrors(t *testing.T) {
interval := newReachabilityInterval(100, 199)
// Sum of sizes greater than the size of the interval
sizes := []uint64{50, 51}
_, err := interval.splitExact(sizes)
if err == nil {
t.Fatalf("TestSplitExactErrors: splitExact unexpectedly " +
"didn't return an error for (sum of sizes) > (size of interval)")
}
expectedErrSubstring := "sum of sizes must be equal to the interval's size"
if !strings.Contains(err.Error(), expectedErrSubstring) {
t.Fatalf("TestSplitExactErrors: splitExact returned wrong error "+
"for (sum of sizes) > (size of interval). "+
"Want: %s, got: %s", expectedErrSubstring, err)
}
// Sum of sizes smaller than the size of the interval
sizes = []uint64{50, 49}
_, err = interval.splitExact(sizes)
if err == nil {
t.Fatalf("TestSplitExactErrors: splitExact unexpectedly " +
"didn't return an error for (sum of sizes) < (size of interval)")
}
expectedErrSubstring = "sum of sizes must be equal to the interval's size"
if !strings.Contains(err.Error(), expectedErrSubstring) {
t.Fatalf("TestSplitExactErrors: splitExact returned wrong error "+
"for (sum of sizes) < (size of interval). "+
"Want: %s, got: %s", expectedErrSubstring, err)
}
}
func TestSplitWithExponentialBiasErrors(t *testing.T) {
interval := newReachabilityInterval(100, 199)
// Sum of sizes greater than the size of the interval
sizes := []uint64{50, 51}
_, err := interval.splitWithExponentialBias(sizes)
if err == nil {
t.Fatalf("TestSplitWithExponentialBiasErrors: splitWithExponentialBias " +
"unexpectedly didn't return an error")
}
expectedErrSubstring := "sum of sizes must be less than or equal to the interval's size"
if !strings.Contains(err.Error(), expectedErrSubstring) {
t.Fatalf("TestSplitWithExponentialBiasErrors: splitWithExponentialBias "+
"returned wrong error. Want: %s, got: %s", expectedErrSubstring, err)
}
}
func TestReindexIntervalErrors(t *testing.T) {
// Create a treeNode and give it size = 100
treeNode := newReachabilityTreeNode(&blockNode{})
treeNode.setInterval(newReachabilityInterval(0, 99))
// Add a chain of 100 child treeNodes to treeNode
var err error
currentTreeNode := treeNode
for i := 0; i < 100; i++ {
childTreeNode := newReachabilityTreeNode(&blockNode{})
_, err = currentTreeNode.addChild(childTreeNode)
if err != nil {
break
}
currentTreeNode = childTreeNode
}
// At the 100th addChild we expect a reindex. This reindex should
// fail because our initial treeNode only has size = 100, and the
// reindex requires size > 100.
// This simulates the case when (somehow) there's more than 2^64
// blocks in the DAG, since the genesis block has size = 2^64.
if err == nil {
t.Fatalf("TestReindexIntervalErrors: reindexIntervals " +
"unexpectedly didn't return an error")
}
if !strings.Contains(err.Error(), "missing tree parent during reindexing") {
t.Fatalf("TestReindexIntervalErrors: reindexIntervals "+
"returned an expected error: %s", err)
}
}
func TestFutureCoveringBlockSetString(t *testing.T) {
treeNodeA := newReachabilityTreeNode(&blockNode{})
treeNodeA.setInterval(newReachabilityInterval(123, 456))
treeNodeB := newReachabilityTreeNode(&blockNode{})
treeNodeB.setInterval(newReachabilityInterval(457, 789))
futureCoveringSet := futureCoveringBlockSet{
&futureCoveringBlock{treeNode: treeNodeA},
&futureCoveringBlock{treeNode: treeNodeB},
}
str := futureCoveringSet.String()
expectedStr := "[123,456][457,789]"
if str != expectedStr {
t.Fatalf("TestFutureCoveringBlockSetString: unexpected "+
"string. Want: %s, got: %s", expectedStr, str)
}
}
func TestReachabilityTreeNodeString(t *testing.T) {
treeNodeA := newReachabilityTreeNode(&blockNode{})
treeNodeA.setInterval(newReachabilityInterval(100, 199))
treeNodeB1 := newReachabilityTreeNode(&blockNode{})
treeNodeB1.setInterval(newReachabilityInterval(100, 150))
treeNodeB2 := newReachabilityTreeNode(&blockNode{})
treeNodeB2.setInterval(newReachabilityInterval(150, 199))
treeNodeC := newReachabilityTreeNode(&blockNode{})
treeNodeC.setInterval(newReachabilityInterval(100, 149))
treeNodeA.children = []*reachabilityTreeNode{treeNodeB1, treeNodeB2}
treeNodeB2.children = []*reachabilityTreeNode{treeNodeC}
str := treeNodeA.String()
expectedStr := "[100,149]\n[100,150][150,199]\n[100,199]"
if str != expectedStr {
t.Fatalf("TestReachabilityTreeNodeString: unexpected "+
"string. Want: %s, got: %s", expectedStr, str)
}
}