diff --git a/src/lib/container/array/array.go b/src/lib/container/array/array.go
index 97f2c43970a..95ed6c2ece4 100644
--- a/src/lib/container/array/array.go
+++ b/src/lib/container/array/array.go
@@ -111,6 +111,17 @@ func (p *Array) Pop() Element {
 
 
 // Partial SortInterface support
+
+export type LessInterface interface {
+	Less(y Element) bool
+}
+
+
+func (p *Array) Less(i, j int) bool {
+	return p.a[i].(LessInterface).Less(p.a[j])
+}
+
+
 func (p *Array) Swap(i, j int) {
 	a := p.a;
 	a[i], a[j] = a[j], a[i]
diff --git a/src/lib/container/array/testarray.go b/src/lib/container/array/testarray.go
index be4928301af..2c56ba8f02d 100644
--- a/src/lib/container/array/testarray.go
+++ b/src/lib/container/array/testarray.go
@@ -8,18 +8,19 @@ import "array"
 import "testing"
 import "sort"
 
+
 export func TestInit(t *testing.T) {
 	var a array.Array;
-	if a.Init(0).Len() != 0 { t.FailNow() }
-	if a.Init(1).Len() != 1 { t.FailNow() }
-	if a.Init(10).Len() != 10 { t.FailNow() }
+	if a.Init(0).Len() != 0 { t.Error("A") }
+	if a.Init(1).Len() != 1 { t.Error("B") }
+	if a.Init(10).Len() != 10 { t.Error("C") }
 }
 
 
 export func TestNew(t *testing.T) {
-	if array.New(0).Len() != 0 { t.FailNow() }
-	if array.New(1).Len() != 1 { t.FailNow() }
-	if array.New(10).Len() != 10 { t.FailNow() }
+	if array.New(0).Len() != 0 { t.Error("A") }
+	if array.New(1).Len() != 1 { t.Error("B") }
+	if array.New(10).Len() != 10 { t.Error("C") }
 }
 
 
@@ -36,7 +37,7 @@ export func TestAccess(t *testing.T) {
 		a.Set(i, Val(i));
 	}
 	for i := 0; i < n; i++ {
-		if a.At(i).(int) != Val(i) { t.FailNow() }
+		if a.At(i).(int) != Val(i) { t.Error(i) }
 	}
 }
 
@@ -46,24 +47,24 @@ export func TestInsertRemoveClear(t *testing.T) {
 	a := array.New(0);
 
 	for i := 0; i < n; i++ {
-		if a.Len() != i { t.FailNow() }
+		if a.Len() != i { t.Errorf("A wrong len %d (expected %d)", a.Len(), i) }
 		a.Insert(0, Val(i));
-		if a.Last().(int) != Val(0) { t.FailNow() }
+		if a.Last().(int) != Val(0) { t.Error("B") }
 	}
 	for i := n-1; i >= 0; i-- {
-		if a.Last().(int) != Val(0) { t.FailNow() }
-		if a.Remove(0).(int) != Val(i) { t.FailNow() }
-		if a.Len() != i { t.FailNow() }
+		if a.Last().(int) != Val(0) { t.Error("C") }
+		if a.Remove(0).(int) != Val(i) { t.Error("D") }
+		if a.Len() != i { t.Errorf("E wrong len %d (expected %d)", a.Len(), i) }
 	}
 
-	if a.Len() != 0 { t.FailNow() }
+	if a.Len() != 0 { t.Errorf("F wrong len %d (expected 0)", a.Len()) }
 	for i := 0; i < n; i++ {
 		a.Push(Val(i));
-		if a.Len() != i+1 { t.FailNow() }
-		if a.Last().(int) != Val(i) { t.FailNow() }
+		if a.Len() != i+1 { t.Errorf("G wrong len %d (expected %d)", a.Len(), i+1) }
+		if a.Last().(int) != Val(i) { t.Error("H") }
 	}
 	a.Init(0);
-	if a.Len() != 0 { t.FailNow() }
+	if a.Len() != 0 { t.Errorf("I wrong len %d (expected 0)", a.Len()) }
 
 	const m = 5;
 	for j := 0; j < m; j++ {
@@ -71,9 +72,21 @@ export func TestInsertRemoveClear(t *testing.T) {
 		for i := 0; i < n; i++ {
 			x := Val(i);
 			a.Push(x);
-			if a.Pop().(int) != x { t.FailNow() }
-			if a.Len() != j+1 { t.FailNow() }
+			if a.Pop().(int) != x { t.Error("J") }
+			if a.Len() != j+1 { t.Errorf("K wrong len %d (expected %d)", a.Len(), j+1) }
 		}
 	}
-	if a.Len() != m { t.FailNow() }
+	if a.Len() != m { t.Errorf("L wrong len %d (expected %d)", a.Len(), m) }
 }
+
+
+/* currently doesn't compile due to linker bug
+export func TestSorting(t *testing.T) {
+	const n = 100;
+	a := array.NewIntArray(n);
+	for i := n-1; i >= 0; i-- {
+		a.Set(i, n-1-i);
+	}
+	if sort.IsSorted(a) { t.Error("not sorted") }
+}
+*/