diff --git a/test/.gitignore b/test/.gitignore
index 9c0284ae..2bd3eb7d 100644
--- a/test/.gitignore
+++ b/test/.gitignore
@@ -1,6 +1,7 @@
 all.log
 *.pyc
 grammar.t
+interval.t
 lexer.t
 lr0.t
 rules.t
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index acc5cf47..d1d9d195 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -11,7 +11,7 @@ include_directories (${CMAKE_SOURCE_DIR}
 include_directories (${CMAKE_INSTALL_PREFIX}/include)
 link_directories(${CMAKE_INSTALL_PREFIX}/lib)
 
-set (test_SRCS grammar.t lexer.t lr0.t rules.t)
+set (test_SRCS grammar.t interval.t lexer.t lr0.t rules.t)
 
 add_custom_target (test ./run_all --verbose
                         DEPENDS ${test_SRCS}
diff --git a/test/interval.t.cpp b/test/interval.t.cpp
new file mode 100644
index 00000000..c5dbb5c9
--- /dev/null
+++ b/test/interval.t.cpp
@@ -0,0 +1,79 @@
+////////////////////////////////////////////////////////////////////////////////
+//
+// Copyright 2015 - 2016, Paul Beckingham, Federico Hernandez.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+//
+// http://www.opensource.org/licenses/mit-license.php
+//
+////////////////////////////////////////////////////////////////////////////////
+
+#include <cmake.h>
+#include <Interval.h>
+#include <test.h>
+
+////////////////////////////////////////////////////////////////////////////////
+int main (int, char**)
+{
+  UnitTest t (15);
+
+  // bool isStarted () const;
+  // bool isEnded () const;
+  Interval i1;
+  t.is (i1.isStarted (), false, "Interval().isStarted -> false");
+  t.is (i1.isEnded (),   false, "Interval().isEnded -> false");
+
+  // void start (Datetime);
+  i1.start (Datetime ());
+  t.is (i1.isStarted (), true, "Interval(start=now).isStarted -> true");
+  t.is (i1.isEnded (),   false, "Interval(start=now).isEnded -> false");
+
+  // void end (Datetime);
+  i1.end (Datetime ());
+  t.is (i1.isStarted (), true, "Interval(start=now,end=now).isStarted -> true");
+  t.is (i1.isEnded (),   true, "Interval(start=now,end=now).isEnded -> true");
+
+  // std::set <std::string> tags () const;
+  // void tag (const std::string&);
+  Interval i2;
+  t.ok (i2.tags () == std::set <std::string> {}, "Interval(tag=) -> {}");
+  i2.tag ("foo");
+  t.ok (i2.tags () == std::set <std::string> {"foo"}, "Interval(tag=foo) -> {foo}");
+  i2.tag ("foo");
+  t.ok (i2.tags () == std::set <std::string> {"foo"}, "Interval(tag=foo,foo) -> {foo}");
+  i2.tag ("bar");
+  t.ok (i2.tags () == std::set <std::string> {"foo", "bar"}, "Interval(tag=foo,bar) -> {foo,bar}");
+
+  // std::string serialize () const;
+  Interval i3;
+  t.is (i3.serialize (), "inc  -  #", "Interval().serialize -> 'inc  -  #'");
+  i3.tag ("foo");
+  t.is (i3.serialize (), "inc  -  # foo", "Interval().serialize -> 'inc  -  # foo'");
+  i3.tag ("bar");
+  t.is (i3.serialize (), "inc  -  # bar foo", "Interval().serialize -> 'inc  -  # bar foo'");
+  i3.start (Datetime(1));
+  t.is (i3.serialize (), "inc 19700101T000001Z -  # bar foo", "Interval(Datetime(1)).serialize -> 'inc 19700101T000001Z -  # bar foo'");
+  i3.end (Datetime(2));
+  t.is (i3.serialize (), "inc 19700101T000001Z - 19700101T000002Z # bar foo", "Interval(Datetime(1)).serialize -> 'inc 19700101T000001Z - 19700101T000002Z # bar foo'");
+
+  return 0;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+