Add fakes for design time view model

src/Elmish.WPF.Tests/ViewModelTests.fs

@@ -26,14 +26,8 @@ module Extensions =
       (?<-) this propName value
 
 
-let private emptyLoggingArgs =
-  { performanceLogThresholdMs = 1
-    nameChain = ""
-    log = NullLogger.Instance
-    logPerformance = NullLogger.Instance }
-
 type internal TestVm<'model, 'msg>(model, bindings) as this =
-  inherit ViewModel<'model, 'msg>({ initialModel = model; dispatch = (fun x -> this.Dispatch x); loggingArgs = emptyLoggingArgs }, bindings)
+  inherit ViewModel<'model, 'msg>({ initialModel = model; dispatch = (fun x -> this.Dispatch x); loggingArgs = LoggingViewModelArgs.fake }, bindings)
 
   let pcTriggers = ConcurrentDictionary<string, int>()
   let ecTriggers = ConcurrentDictionary<string, int>()

src/Elmish.WPF/ViewModelArgs.fs

@@ -20,6 +20,13 @@ module internal LoggingViewModelArgs =
 
   let map nameChain v = { v with nameChain = nameChain }
 
+  let none =
+    { performanceLogThresholdMs = 1
+      log = NullLogger.Instance
+      logPerformance = NullLogger.Instance
+      nameChain = "" }
+
+
 type internal ViewModelArgs<'model, 'msg> =
   { initialModel: 'model
     dispatch: 'msg -> unit
@@ -35,3 +42,8 @@ module internal ViewModelArgs =
     { initialModel = v.initialModel |> mapModel
       dispatch = mapMsg >> v.dispatch
       loggingArgs = v.loggingArgs }
+
+  let simple initialModel =
+    { initialModel = initialModel
+      dispatch = ignore
+      loggingArgs = LoggingViewModelArgs.none }

src/Elmish.WPF/ViewModelModule.fs

@@ -1,16 +1,7 @@
 module Elmish.WPF.ViewModel
 
-open Microsoft.Extensions.Logging.Abstractions
-
 /// Creates a design-time view model using the given model and bindings.
 let designInstance (model: 'model) (bindings: Binding<'model, 'msg> list) =
-  let args =
-    { initialModel = model
-      dispatch = ignore
-      loggingArgs =
-        { performanceLogThresholdMs = 1
-          nameChain = "main"
-          log = NullLogger.Instance
-          logPerformance = NullLogger.Instance } }
+  let args = ViewModelArgs.simple model
 
   ViewModel(args, bindings) |> box