Added interval stream operator for tests.

Author: 5cript

tests/interval_io.hpp

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <interval-tree/interval_tree.hpp>
+
+#include <iostream>
+
+namespace lib_interval_tree
+{
+    template <typename... IntervalArgs>
+    std::ostream&
+    operator<<(std::ostream& os, lib_interval_tree::interval<IntervalArgs...> const& interval)
+    {
+        os << '[' << interval.low() << ", " << interval.high() << ']';
+        return os;
+    }
+}