container/list: improve test coverage

R=golang-codereviews, dave, gobot, bradfitz, gri
CC=golang-codereviews
https://golang.org/cl/46640043

diff --git a/src/pkg/container/list/list_test.go b/src/pkg/container/list/list_test.go
index ee52afe82b9aac13c4ad0d6cd10edf62009f0d20..df06c423fe5b7dc558861a6e3848c32a58100e84 100644 (file)
--- a/src/pkg/container/list/list_test.go
+++ b/src/pkg/container/list/list_test.go
@@ -285,3 +285,42 @@ func TestMove(t *testing.T) {
        checkListPointers(t, l, []*Element{e1, e3, e2, e4})
        e1, e2, e3, e4 = e1, e3, e2, e4
 }
+
+// Test PushFront, PushBack, PushFrontList, PushBackList with uninitialized List
+func TestZeroList(t *testing.T) {
+       var l1 = new(List)
+       l1.PushFront(1)
+       checkList(t, l1, []interface{}{1})
+
+       var l2 = new(List)
+       l2.PushBack(1)
+       checkList(t, l2, []interface{}{1})
+
+       var l3 = new(List)
+       l3.PushFrontList(l1)
+       checkList(t, l3, []interface{}{1})
+
+       var l4 = new(List)
+       l4.PushBackList(l2)
+       checkList(t, l4, []interface{}{1})
+}
+
+// Test that a list l is not modified when calling InsertBefore with a mark that is not an element of l.
+func TestInsertBeforeUnknownMark(t *testing.T) {
+       var l List
+       l.PushBack(1)
+       l.PushBack(2)
+       l.PushBack(3)
+       l.InsertBefore(1, new(Element))
+       checkList(t, &l, []interface{}{1, 2, 3})
+}
+
+// Test that a list l is not modified when calling InsertAfter with a mark that is not an element of l.
+func TestInsertAfterUnknownMark(t *testing.T) {
+       var l List
+       l.PushBack(1)
+       l.PushBack(2)
+       l.PushBack(3)
+       l.InsertAfter(1, new(Element))
+       checkList(t, &l, []interface{}{1, 2, 3})
+}