feat: add tunable polling interval with conservative defaults to async predicate checks

asynctest/private/asyncdispatch/eventually.nim

@@ -1,14 +1,14 @@
 import std/asyncdispatch
 import std/times
 
-template eventually*(expression: untyped, timeout=5000): bool =
+template eventually*(expression: untyped, timeout=5000, pollInterval=1000): bool =
 
   proc eventually: Future[bool] {.async.} =
     let endTime = getTime() + initDuration(milliseconds=timeout)
     while not expression:
       if endTime < getTime():
         return false
-      await sleepAsync(10)
+      await sleepAsync(pollInterval)
     return true
 
   await eventually()

asynctest/private/chronos/eventually.nim

@@ -10,7 +10,7 @@ template eventuallyProcSignature(body: untyped): untyped =
     proc eventually: Future[bool] {.async.} =
       body
 
-template eventually*(expression: untyped, timeout=5000): bool =
+template eventually*(expression: untyped, timeout=5000, pollInterval=1000): bool =
   bind Moment, now, milliseconds
 
   eventuallyProcSignature:
@@ -18,7 +18,7 @@ template eventually*(expression: untyped, timeout=5000): bool =
     while not expression:
       if endTime < Moment.now():
         return false
-      await sleepAsync(10.milliseconds)
+      await sleepAsync(pollInterval.milliseconds)
     return true
 
   await eventually()

testmodules/common/testbody.nim

@@ -42,13 +42,13 @@ suite "eventually":
       inc tries
       tries == 3
 
-    check eventually becomesTrue()
+    check eventually(becomesTrue(), pollInterval=10)
 
   test "becomes false after timeout":
 
     proc remainsFalse: bool = false
 
-    check not eventually(remainsFalse(), timeout=100)
+    check not eventually(remainsFalse(), timeout=100, pollInterval=10)
 
   test "becomes true during timeout":
 
@@ -56,7 +56,7 @@ suite "eventually":
       sleep(100)
       true
 
-    check eventually(slowTrue(), timeout=50)
+    check eventually(slowTrue(), timeout=50, pollInterval=10)
 
   test "works with async procedures":
 
@@ -70,5 +70,21 @@ suite "eventually":
       x = 42
 
     let future = slowProcedure()
-    check eventually x == 42
+    check eventually(x == 42, pollInterval=10)
     await future
+
+  test "respects poll interval":
+    var evaluations: int = 0
+
+    # If we try to access this from the closure, it will crash later with
+    # a segfault, so pass as var.
+    proc expensivePredicate(counter: var int): bool =
+      inc counter
+      return false
+
+    check not eventually(evaluations.expensivePredicate(), pollInterval=100, timeout=500)
+    check 1 <= evaluations and evaluations <= 6
+
+    evaluations = 0
+    check not eventually(evaluations.expensivePredicate(), pollInterval=10, timeout=500)
+    check 20 <= evaluations and evaluations <= 51