fixed bug with invalid handling for RampingConstant load simulations

src/NBomber/Domain/LoadSimulation.fs

@@ -148,7 +148,7 @@ let create (simulations: Contracts.LoadSimulation list) =
 
 let inline getSimulationInterval simulation =
     match simulation with
-    | RampingConstant (copies, during)      -> during
+    | RampingConstant (copies, during)      -> Constants.DefaultSchedulerTickInterval
     | KeepConstant (copies, during)         -> during
     | RampingInject (_, interval, during)   -> interval
     | Inject (rate, interval, during)       -> interval

tests/NBomber.IntegrationTests/Concurrency/ConstantActorSchedulerTests.fs

@@ -98,3 +98,27 @@ let ``Stop should stop all working actors`` () =
     test <@ scheduler.ScheduledActorCount = 5 @>
     test <@ Seq.length workingActors = 0 @>
     test <@ scheduler.AvailableActors.Count = 5 @>
+
+[<Fact>]
+let ``RampingConstant should work correctly`` () =
+
+    Scenario.create("scenario", fun ctx -> task {
+
+        let! step = Step.run("step", ctx, fun () -> task {
+            do! Task.Delay(milliseconds 100)
+            return Response.ok()
+        })
+
+        return Response.ok()
+    })
+    |> Scenario.withoutWarmUp
+    |> Scenario.withLoadSimulations [RampingConstant(copies = 10, during = seconds 5)]
+    |> NBomberRunner.registerScenario
+    |> NBomberRunner.withoutReports
+    |> NBomberRunner.run
+    |> Result.getOk
+    |> fun nodeStats ->
+        let stats = nodeStats.ScenarioStats[0]
+
+        test <@ stats.AllRequestCount > 0 @>
+        test <@ stats.Ok.Request.Count > 0 @>