Re-write tests to avoid ==>

NightLight.Core.Tests/InteractionListGenerators.fs

@@ -0,0 +1,41 @@
+module NightLight.Core.Tests.InteractionListGenerators
+
+open System
+open FsCheck.FSharp
+open NightLight.Core.Models
+
+let private genTimeChangedInteraction =
+    ArbMap.defaults |> ArbMap.generate<DateTime> |> Gen.map Interaction.TimeChanged
+
+let private genHumanInteraction =
+    Gen.elements lights
+    |> Gen.bind (fun light ->
+        [ LightTurnedOn light; LightTurnedOff light ]
+        |> Gen.elements
+        |> Gen.map Interaction.HumanInteraction)
+
+let private genInteraction =
+    Gen.oneof [ genTimeChangedInteraction; genHumanInteraction ]
+
+let private genInteractionsListThatStartsWithTimeChange =
+    gen {
+        let! firstInteraction = genTimeChangedInteraction
+        let! remainingInteractions = Gen.listOf genInteraction
+        return firstInteraction :: remainingInteractions
+    }
+
+let private genInteractionsListWhere condition =
+    Gen.listOf (genInteraction |> Gen.filter condition)
+
+let genInteractionsListThatEndsAtTime time =
+    let genTrivialList = Gen.constant <| List.singleton (Interaction.TimeChanged time)
+
+    let genNonTrivialList =
+        gen {
+            let! before = genInteractionsListThatStartsWithTimeChange
+            let interactionThatSetsEndTime = Interaction.TimeChanged time
+            let! after = genInteractionsListWhere (not << _.IsTimeChanged)
+            return before @ interactionThatSetsEndTime :: after
+        }
+
+    Gen.frequency [ 1, genTrivialList; 9, genNonTrivialList ]