diff --git a/gtsam/discrete/tests/testDecisionTree.cpp b/gtsam/discrete/tests/testDecisionTree.cpp
index c157a2543..c338bb86f 100644
--- a/gtsam/discrete/tests/testDecisionTree.cpp
+++ b/gtsam/discrete/tests/testDecisionTree.cpp
@@ -308,7 +308,7 @@ TEST(DecisionTree, Containers) {
   StringContainerTree tree;
 
   // Create small two-level tree
-  string A("A"), B("B"), C("C");
+  string A("A"), B("B");
   DT stringIntTree(B, DT(A, 0, 1), DT(A, 2, 3));
 
   // Check conversion
@@ -324,7 +324,7 @@ TEST(DecisionTree, Containers) {
 // Test visit.
 TEST(DecisionTree, visit) {
   // Create small two-level tree
-  string A("A"), B("B"), C("C");
+  string A("A"), B("B");
   DT tree(B, DT(A, 0, 1), DT(A, 2, 3));
   double sum = 0.0;
   auto visitor = [&](int y) { sum += y; };
@@ -336,7 +336,7 @@ TEST(DecisionTree, visit) {
 // Test visit, with Choices argument.
 TEST(DecisionTree, visitWith) {
   // Create small two-level tree
-  string A("A"), B("B"), C("C");
+  string A("A"), B("B");
   DT tree(B, DT(A, 0, 1), DT(A, 2, 3));
   double sum = 0.0;
   auto visitor = [&](const Assignment<string>& choices, int y) { sum += y; };
@@ -348,7 +348,7 @@ TEST(DecisionTree, visitWith) {
 // Test fold.
 TEST(DecisionTree, fold) {
   // Create small two-level tree
-  string A("A"), B("B"), C("C");
+  string A("A"), B("B");
   DT tree(B, DT(A, 0, 1), DT(A, 2, 3));
   auto add = [](const int& y, double x) { return y + x; };
   double sum = tree.fold(add, 0.0);
@@ -359,14 +359,14 @@ TEST(DecisionTree, fold) {
 // Test retrieving all labels.
 TEST(DecisionTree, labels) {
   // Create small two-level tree
-  string A("A"), B("B"), C("C");
+  string A("A"), B("B");
   DT tree(B, DT(A, 0, 1), DT(A, 2, 3));
   auto labels = tree.labels();
   EXPECT_LONGS_EQUAL(2, labels.size());
 }
 
 /* ******************************************************************************** */
-// Test retrieving all labels.
+// Test unzip method.
 TEST(DecisionTree, unzip) {
   using DTP = DecisionTree<string, std::pair<int, string>>;
   using DT1 = DecisionTree<string, int>;
@@ -390,6 +390,29 @@ TEST(DecisionTree, unzip) {
   EXPECT(tree2.equals(dt2));
 }
 
+/* ************************************************************************** */
+// Test thresholding.
+TEST(DecisionTree, threshold) {
+  // Create three level tree
+  vector<DT::LabelC> keys;
+  keys += DT::LabelC("C", 2), DT::LabelC("B", 2), DT::LabelC("A", 2);
+  DT tree(keys, "0 1 2 3 4 5 6 7");
+
+  // Check number of elements equal to zero
+  auto count = [](const int& value, int count) {
+    return value == 0 ? count + 1 : count;
+  };
+  EXPECT_LONGS_EQUAL(1, tree.fold(count, 0));
+
+  // Now threshold
+  auto threshold = [](int value) { return value < 5 ? 0 : value; };
+  DT thresholded(tree, threshold);
+
+  // Check number of elements equal to zero now = 5
+  // TODO(frank): it is 2, because the pruned branches are counted as 1!
+  EXPECT_LONGS_EQUAL(5, thresholded.fold(count, 0));
+}
+
 /* ************************************************************************* */
 int main() {
   TestResult tr;