uasyncio.core: Add test for fair scheduling.

uasyncio.core/test_fair_schedule.py

@@ -0,0 +1,34 @@
+# Test that uasyncio scheduling is fair, i.e. gives all
+# coroutines equal chance to run (this specifically checks
+# round-robin scheduling).
+import uasyncio.core as asyncio
+
+
+COROS = 5
+ITERS = 5
+
+
+result = []
+
+
+async def coro(n):
+    for i in range(ITERS):
+        result.append(n)
+        yield
+
+
+async def done():
+    while True:
+        if len(result) == COROS * ITERS:
+            #print(result)
+            assert result == list(range(COROS)) * ITERS
+            return
+        yield
+
+
+loop = asyncio.get_event_loop()
+
+for n in range(COROS):
+    loop.create_task(coro(n))
+
+loop.run_until_complete(done())