Add a minimal test for #8.

tests/0-waitercount.d

@@ -0,0 +1,33 @@
+/++ dub.sdl:
+	name "test"
+	dependency "eventcore" path=".."
++/
+module test;
+
+import eventcore.core;
+import core.stdc.signal;
+import core.time : Duration, msecs;
+import core.thread : Thread;
+
+
+void test(Duration timeout)
+{
+	while (true) {
+		auto reason = eventDriver.core.processEvents(timeout);
+		final switch (reason) with (ExitReason) {
+			case exited: assert(false, "Manual exit without call to exit()!?");
+			case timeout: assert(false, "Event loop timed out, although no waiters exist!?");
+			case idle: break;
+			case outOfWaiters: return;
+		}
+	}
+}
+
+void main()
+{
+	assert(eventDriver.core.waiterCount == 0, "Initial waiter count not 0!");
+	test(100.msecs);
+	assert(eventDriver.core.waiterCount == 0, "Waiter count after outOfWaiters not 0!");
+	test(Duration.max);
+	assert(eventDriver.core.waiterCount == 0);
+}