diff --git a/tests/cpp/tree/test_param.cc b/tests/cpp/tree/test_param.cc
new file mode 100644
index 000000000..916901183
--- /dev/null
+++ b/tests/cpp/tree/test_param.cc
@@ -0,0 +1,77 @@
+// Copyright by Contributors
+#include "../../src/tree/param.h"
+
+#include "../helpers.h"
+
+TEST(Param, VectorIOStream) {
+  std::vector<int> vals = {3, 2, 1};
+  std::stringstream ss;
+  std::vector<int> vals_in;
+  
+  ss << vals;
+  EXPECT_EQ(ss.str(), "(3,2,1)");
+
+  ss >> vals_in;
+  EXPECT_EQ(vals_in, vals);
+
+  vals.clear(); ss.flush(); ss.clear(); ss.str("");
+  vals = {1};
+  ss << vals;
+  EXPECT_EQ(ss.str(), "(1,)");
+}
+
+TEST(Param, VectorStreamRead) {
+  std::vector<int> vals = {3, 2, 1};
+  std::stringstream ss;
+  std::vector<int> vals_in;
+
+  vals_in.clear(); ss.flush(); ss.clear(); ss.str("");
+  ss << "(3, 2, 1)";
+  ss >> vals_in;
+  EXPECT_EQ(vals_in, vals);
+
+  vals_in.clear(); ss.flush(); ss.clear(); ss.str("");
+  ss << "(3L,2L,1L)";
+  ss >> vals_in;
+  EXPECT_EQ(vals_in, vals);
+
+  vals_in.clear(); ss.flush(); ss.clear(); ss.str("");
+  ss << " (3,2,1,)";
+  ss >> vals_in;
+  EXPECT_EQ(vals_in, vals);
+
+  vals_in.clear(); ss.flush(); ss.clear(); ss.str("");
+  ss << " ( 3, 2,1 )";
+  ss >> vals_in;
+  EXPECT_EQ(vals_in, vals);
+
+  vals_in.clear(); ss.flush(); ss.clear(); ss.str("");
+  ss << " ( 3, 2,1 ) ";
+  ss >> vals_in;
+  EXPECT_EQ(vals_in, vals);
+
+  vals_in.clear(); ss.flush(); ss.clear(); ss.str("");
+  ss << " 321 ";
+  ss >> vals_in;
+  EXPECT_EQ(vals_in[0], 321);
+
+  vals_in.clear(); ss.flush(); ss.clear(); ss.str("");
+  ss << "(3.0,2,1)";
+  ss >> vals_in;
+  EXPECT_NE(vals_in, vals);
+
+  vals_in.clear(); ss.flush(); ss.clear(); ss.str("");
+  ss << "1a";
+  ss >> vals_in;
+  EXPECT_NE(vals_in, vals);
+
+  vals_in.clear(); ss.flush(); ss.clear(); ss.str("");
+  ss << "abcde";
+  ss >> vals_in;
+  EXPECT_NE(vals_in, vals);
+
+  vals_in.clear(); ss.flush(); ss.clear(); ss.str("");
+  ss << "(3,2,1";
+  ss >> vals_in;
+  EXPECT_NE(vals_in, vals);
+}