Three basic ioloop tests.

tests/conftest.py

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+from psyclone import ioloop
+
+def pytest_funcarg__IOloop(request):
+    '''Funcarg to create a ioloop that is not the standard ioloop. This allows
+    test teardown more easily. It also allows testing of independent
+    IOLoops.'''
+    return ioloop.IOLoop()

tests/test_ioloop.py

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+from psyclone import ioloop
+import os
+def test_class_instance():
+    '''Ensure two calls to ioloop.instance create only one object.'''
+    assert not hasattr(ioloop.IOLoop, '_instance')
+    assert ioloop.IOLoop.instance() == ioloop.IOLoop.instance()
+    assert hasattr(ioloop.IOLoop, '_instance')
+    assert ioloop.IOLoop.initialized()
+    del ioloop.IOLoop._instance
+
+def test_ioloop_funcarg(IOloop):
+    '''Ensure the ioloop funcarg isn't from instance'''
+    assert isinstance(IOloop, ioloop.IOLoop)
+    assert not hasattr(ioloop.IOLoop, '_instance')
+
+def test_run_loop(IOloop):
+    '''Test adding a file descriptor to the IOLoop and it receives events.'''
+    fdr, fdw = os.pipe()
+    reader = os.fdopen(fdr, "rb", 0)
+    writer = os.fdopen(fdw, "wb", 0)
+    IOloop._set_nonblocking(fdr)
+    IOloop._set_nonblocking(fdw)
+    read_values = []
+    def read_callback(fd, events):
+        assert fd == fdr
+        assert events & ioloop.IOLoop.READ
+        assert IOloop.running()
+        val = reader.read()
+        if  val != None:
+            assert val == b"ho"
+            IOloop.stop()
+    def send_val():
+        writer.write("ho")
+    IOloop.add_handler(fdr, read_callback, IOloop.READ)
+    IOloop.add_callback(send_val)
+    IOloop.start()