simplify dht mock and restore clock after accelerating

tests/dht_mocks.py

@@ -9,7 +9,7 @@ if typing.TYPE_CHECKING:
 
 
 def get_time_accelerator(loop: asyncio.AbstractEventLoop,
-                         now: typing.Optional[float] = None) -> typing.Callable[[float], typing.Awaitable[None]]:
+                         instant_step: bool = False) -> typing.Callable[[float], typing.Awaitable[None]]:
     """
     Returns an async advance() function
 
@@ -17,32 +17,22 @@ def get_time_accelerator(loop: asyncio.AbstractEventLoop,
     made by call_later, call_at, and call_soon.
     """
 
-    _time = now or loop.time()
-    loop.time = functools.wraps(loop.time)(lambda: _time)
+    original = loop.time
+    _drift = 0
+    loop.time = functools.wraps(loop.time)(lambda: original() + _drift)
 
     async def accelerate_time(seconds: float) -> None:
-        nonlocal _time
+        nonlocal _drift
         if seconds < 0:
             raise ValueError(f'Cannot go back in time ({seconds} seconds)')
-        _time += seconds
-        await past_events()
-        await asyncio.sleep(0)
-
-    async def past_events() -> None:
-        while loop._scheduled:
-            timer: asyncio.TimerHandle = loop._scheduled[0]
-            if timer not in loop._ready and timer._when <= _time:
-                loop._scheduled.remove(timer)
-                loop._ready.append(timer)
-            if timer._when > _time:
-                break
+        _drift += seconds
         await asyncio.sleep(0)
 
     async def accelerator(seconds: float):
-        steps = seconds * 10.0
+        steps = seconds * 10.0 if not instant_step else 1
 
         for _ in range(max(int(steps), 1)):
-            await accelerate_time(0.1)
+            await accelerate_time(seconds/steps)
 
     return accelerator