diff --git a/test_suite/simgear_tests/CMakeLists.txt b/test_suite/simgear_tests/CMakeLists.txt
index e1f7a98f0..32e8dcffd 100644
--- a/test_suite/simgear_tests/CMakeLists.txt
+++ b/test_suite/simgear_tests/CMakeLists.txt
@@ -3,6 +3,7 @@ foreach( simgear_test_category
         math
         props
         canvas 
+        structure
     )
 
     add_subdirectory(${simgear_test_category})
diff --git a/test_suite/simgear_tests/structure/CMakeLists.txt b/test_suite/simgear_tests/structure/CMakeLists.txt
new file mode 100644
index 000000000..094a1543b
--- /dev/null
+++ b/test_suite/simgear_tests/structure/CMakeLists.txt
@@ -0,0 +1,12 @@
+set(TESTSUITE_SOURCES
+    ${TESTSUITE_SOURCES}
+    ${CMAKE_CURRENT_SOURCE_DIR}/TestSuite.cxx
+    ${CMAKE_CURRENT_SOURCE_DIR}/test_event.cxx
+    PARENT_SCOPE
+)
+
+set(TESTSUITE_HEADERS
+    ${TESTSUITE_HEADERS}
+    ${CMAKE_CURRENT_SOURCE_DIR}/test_event.hxx
+    PARENT_SCOPE
+)
diff --git a/test_suite/simgear_tests/structure/TestSuite.cxx b/test_suite/simgear_tests/structure/TestSuite.cxx
new file mode 100644
index 000000000..7cb681a3b
--- /dev/null
+++ b/test_suite/simgear_tests/structure/TestSuite.cxx
@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2016 Edward d'Auvergne
+ *
+ * This file is part of the program FlightGear.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "test_event.hxx"
+
+
+// Set up the tests.
+CPPUNIT_TEST_SUITE_NAMED_REGISTRATION(SimgearEventTests, "Simgear unit tests");
diff --git a/test_suite/simgear_tests/structure/test_event.cxx b/test_suite/simgear_tests/structure/test_event.cxx
new file mode 100644
index 000000000..e7d9dd483
--- /dev/null
+++ b/test_suite/simgear_tests/structure/test_event.cxx
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2016 Edward d'Auvergne
+ *
+ * This file is part of the program FlightGear.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#include "test_event.hxx"
+
+#include <algorithm>
+
+using namespace std;
+
+namespace {
+
+SGEventMgr* global_eventManager = nullptr;
+double global_realTime = 0.0;
+
+// class which behaves similarly to TimerObj in NasalSys
+class FakeNasalTimer
+{
+public:
+    FakeNasalTimer(string n) : _name(n)
+    {
+    }
+
+    void invoke()
+    {
+        ++_invokeCount;
+
+        if (_expectedTime > 0.0) {
+            CPPUNIT_ASSERT_DOUBLES_EQUAL(_expectedTime, global_realTime, 0.1);
+        }
+
+        // rescheudle base don the next time
+        if (!_rescheduleTimes.empty()) {
+            const auto t = _rescheduleTimes.front();
+            _rescheduleTimes.pop_front();
+
+            // TimerObj does this, eugh
+            global_eventManager->removeTask(_name);
+            start(t);
+        }
+    }
+
+    void start(double interval)
+    {
+        global_eventManager->addTask(_name, this, &FakeNasalTimer::invoke,
+                                     interval, interval /* delay */, false);
+
+        _expectedTime = global_realTime + interval;
+    }
+
+    string _name;
+    deque<double> _rescheduleTimes;
+    int _invokeCount = 0;
+    double _expectedTime = 0.0;
+};
+
+} // namespace
+
+// Set up function for each test.
+void SimgearEventTests::setUp()
+{
+    _eventManager = new SGEventMgr;
+    global_eventManager = _eventManager;
+    _eventManager->init();
+
+    _realTimeProp = new SGPropertyNode{};
+    _eventManager->setRealtimeProperty(_realTimeProp);
+}
+
+
+// Clean up after each test.
+void SimgearEventTests::tearDown()
+{
+    global_eventManager = nullptr;
+}
+
+void SimgearEventTests::runForTestTime(double totalTime, double updateHz, double simTimeScaling)
+{
+    const double dt = 1.0 / updateHz;
+    const int updateCount = static_cast<int>(totalTime * updateHz);
+    const double simDt = dt * simTimeScaling;
+    _realTimeProp->setDoubleValue(dt);
+    global_realTime = 0.0;
+
+    for (int c = 0; c < updateCount; ++c) {
+        const double newRealTime = global_realTime + dt;
+        global_realTime = newRealTime;
+        _eventManager->update(simDt);
+    }
+}
+
+void SimgearEventTests::testTaskRescheduleDuringRun()
+{
+    auto t1 = new FakeNasalTimer("timer_aaa");
+    t1->_rescheduleTimes.resize(10);
+    fill(t1->_rescheduleTimes.begin(), t1->_rescheduleTimes.end(), 0.5);
+    t1->_rescheduleTimes.push_back(30.0); // large final value
+
+    global_realTime = 0.0;
+    t1->start(1.0);
+    runForTestTime(8.0, 20);
+
+    CPPUNIT_ASSERT_EQUAL(11, t1->_invokeCount);
+}
diff --git a/test_suite/simgear_tests/structure/test_event.hxx b/test_suite/simgear_tests/structure/test_event.hxx
new file mode 100644
index 000000000..029152526
--- /dev/null
+++ b/test_suite/simgear_tests/structure/test_event.hxx
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2016 Edward d'Auvergne
+ *
+ * This file is part of the program FlightGear.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#pragma once
+
+#include <cppunit/TestFixture.h>
+#include <cppunit/extensions/HelperMacros.h>
+
+#include <simgear/props/props.hxx>
+#include <simgear/structure/event_mgr.hxx>
+
+// The unit tests of the simgear property tree.
+class SimgearEventTests : public CppUnit::TestFixture
+{
+    // Set up the test suite.
+    CPPUNIT_TEST_SUITE(SimgearEventTests);
+    CPPUNIT_TEST(testTaskRescheduleDuringRun);
+    CPPUNIT_TEST_SUITE_END();
+
+public:
+    // Set up function for each test.
+    void setUp();
+
+    // Clean up after each test.
+    void tearDown();
+
+    void runForTestTime(double totalTime, double updateHz, double simTimeScaling = 1.0);
+
+    // The tests.
+    void testTaskRescheduleDuringRun();
+
+private:
+    SGSharedPtr<SGEventMgr> _eventManager;
+    SGPropertyNode_ptr _realTimeProp;
+    SGPropertyNode_ptr _freezeProp;
+};