Rephrase task_cancel tests in the form of a boost_test.

tests/task_cancel.cpp

@@ -1,16 +1,92 @@
+#define BOOST_TEST_MODULE fc_task_cancel_tests
+#include <boost/test/unit_test.hpp>
+
 #include <fc/thread/thread.hpp>
 #include <fc/log/logger.hpp>
 #include <fc/exception/exception.hpp>
 
-int main( int argc, char** argv )
+BOOST_AUTO_TEST_CASE( cancel_an_active_task )
 {
-   try {
-       auto result = fc::schedule( [=]() { ilog( "hello world" ); }, fc::time_point::now() + fc::seconds(3) );
-       result.cancel();
-       result.wait();
-   } 
-   catch ( const fc::exception& e )
-   {
-      wlog( "${e}", ("e",e.to_detail_string() ) );
-   }
+  enum task_result{sleep_completed, sleep_aborted};
+  fc::future<task_result> task = fc::async([]() {
+    BOOST_TEST_MESSAGE("Starting async task");
+    try
+    {
+      fc::usleep(fc::seconds(5));
+      return sleep_completed;
+    }
+    catch (const fc::exception&)
+    {
+      return sleep_aborted;
+    }
+  });
+
+  fc::time_point start_time = fc::time_point::now();
+
+  // wait a bit for the task to start running
+  fc::usleep(fc::milliseconds(100));
+
+  BOOST_TEST_MESSAGE("Canceling task");
+  task.cancel();
+  try
+  {
+    task_result result = task.wait();
+    BOOST_CHECK_MESSAGE(result != sleep_completed, "sleep should have been canceled");
+  }
+  catch (fc::exception& e)
+  {
+    BOOST_TEST_MESSAGE("Caught exception from canceled task: " << e.what());
+    BOOST_CHECK_MESSAGE(fc::time_point::now() - start_time < fc::seconds(4), "Task was not canceled quickly");
+  }
 }
+
+
+BOOST_AUTO_TEST_CASE( cleanup_cancelled_task )
+{
+  std::shared_ptr<std::string> some_string(std::make_shared<std::string>("some string"));
+  fc::future<void> task = fc::async([some_string]() {
+    BOOST_TEST_MESSAGE("Starting async task, bound string is " << *some_string);
+    try
+    {
+      fc::usleep(fc::seconds(5));
+      BOOST_TEST_MESSAGE("Finsihed usleep in async task, leaving the task's functor");
+    }
+    catch (...)
+    {
+      BOOST_TEST_MESSAGE("Caught exception in async task, leaving the task's functor");
+    }
+  });
+  std::weak_ptr<std::string> weak_string_ptr(some_string);
+  some_string.reset();
+  BOOST_CHECK_MESSAGE(!weak_string_ptr.expired(), "Weak pointer should still be valid because async task should be holding the strong pointer");
+  fc::usleep(fc::milliseconds(100));
+  BOOST_TEST_MESSAGE("Canceling task");
+  task.cancel();
+  try
+  {
+    task.wait();
+  }
+  catch (fc::exception& e)
+  {
+    BOOST_TEST_MESSAGE("Caught exception from canceled task: " << e.what());
+  }
+  BOOST_CHECK_MESSAGE(weak_string_ptr.expired(), "Weak pointer should now be invalid because async task should be done with it");
+  task = fc::future<void>();
+  BOOST_CHECK_MESSAGE(weak_string_ptr.expired(), "Weak pointer should now be invalid because async task should have been destroyed");
+}
+
+BOOST_AUTO_TEST_CASE( cancel_scheduled_task )
+{
+  bool task_executed = false;
+  try 
+  {
+    auto result = fc::schedule( [&]() { task_executed = true; }, fc::time_point::now() + fc::seconds(3) );
+    result.cancel();
+    result.wait();
+  } 
+  catch ( const fc::exception& e )
+  {
+    wlog( "${e}", ("e",e.to_detail_string() ) );
+  }
+  BOOST_CHECK(!task_executed);
+}