Fix that Ctrie iterator did not return entries from tNodes.

Fixes #171

Author: fasaxc

trie/ctrie/ctrie.go

@@ -1,5 +1,5 @@
 /*
-Copyright 2015 Workiva, LLC
+Copyright 2015-2017 Workiva, LLC and others.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -405,6 +405,8 @@ func (c *Ctrie) traverse(i *iNode, ch chan<- *Entry, cancel <-chan struct{}) err
 				return errCanceled
 			}
 		}
+	case main.tNode != nil:
+		ch <- main.tNode.Entry
 	}
 	return nil
 }

trie/ctrie/ctrie_test.go

@@ -341,6 +341,24 @@ func TestIterator(t *testing.T) {
 	assert.False(ok)
 }
 
+// TestIteratorCoversTNodes reproduces the scenario of a bug where tNodes weren't being traversed.
+func TestIteratorCoversTNodes(t *testing.T) {
+	assert := assert.New(t)
+	ctrie := New(mockHashFactory)
+	// Add a pair of keys that collide (because we're using the mock hash).
+	ctrie.Insert([]byte("a"), true)
+	ctrie.Insert([]byte("b"), true)
+	// Delete one key, leaving exactly one sNode in the cNode.  This will
+	// trigger creation of a tNode.
+	ctrie.Remove([]byte("b"))
+	seenKeys := map[string]bool{}
+	for entry := range ctrie.Iterator(nil) {
+		seenKeys[string(entry.Key)] = true
+	}
+	assert.Contains(seenKeys, "a", "Iterator did not return 'a'.")
+	assert.Len(seenKeys, 1)
+}
+
 func TestSize(t *testing.T) {
 	ctrie := New(nil)
 	for i := 0; i < 10; i++ {