Add spec showing that users can animate revealing when prepending or …

…appending, but not when swapping

lib/assets/javascripts/unpoly/classes/scroll_motion.coffee

@@ -3,14 +3,14 @@ u = up.util
 class up.ScrollMotion
 
   # We want to make the default speed mimic Chrome's smooth scrolling behavior.
-  # We also want to keep the default  valuein up.viewport.config.scrollSpeed to be 1.
+  # We also want to keep the default value in up.viewport.config.scrollSpeed to be 1.
   # For our calculation in #animationFrame() we need to multiply it with this factor.
   SPEED_CALIBRATION = 0.065
 
   constructor: (@scrollable, @targetTop, options = {}) ->
     # The option for up.scroll() is { behavior }, but coming
     # from up.replace() it's { scrollBehavior }.
-    @behavior = options.behavior ? options.scrollBehavior ? 'instant'
+    @behavior = options.behavior ? options.scrollBehavior ? 'auto'
 
     # The option for up.scroll() is { behavior }, but coming
     # from up.replace() it's { scrollSpeed }.

lib/assets/javascripts/unpoly/motion.coffee.erb

@@ -372,7 +372,7 @@ up.motion = do ->
 
     scrollNew = ->
       # Don't animate the scrolling.
-      scrollOptions = u.merge(options, behavior: 'instant')
+      scrollOptions = u.merge(options, scrollBehavior: 'auto')
       # Scroll newElement into position before we start the enter animation.
       up.viewport.scrollAfterInsertFragment(newElement, scrollOptions)
 

spec_app/spec/javascripts/up/fragment_spec.js.coffee

@@ -1965,6 +1965,30 @@ describe 'up.fragment', ->
             next =>
               expect(swapDirectlySpy).toHaveBeenCalled()
 
+      describe 'with { scrollBehavior } option', ->
+
+        beforeEach ->
+          up.viewport.knife.mock('reveal').and.callFake (element, options) =>
+            @revealScrollBehavior = options.behavior ? options.scrollBehavior
+
+        it 'animates the revealing when prepending an element', asyncSpec (next) ->
+          fixture('.element', text: 'version 1')
+          up.extract('.element:before', '<div class="element">version 2</div>', reveal: true, scrollBehavior: 'smooth')
+          next =>
+            expect(@revealScrollBehavior).toEqual('smooth')
+
+        it 'animates the revealing when appending an element', asyncSpec (next) ->
+          fixture('.element', text: 'version 1')
+          up.extract('.element:after', '<div class="element">version 2</div>', reveal: true, scrollBehavior: 'smooth')
+          next =>
+            expect(@revealScrollBehavior).toEqual('smooth')
+
+        it 'does not animate the revealing when swapping out an element', asyncSpec (next) ->
+          fixture('.element', text: 'version 1')
+          up.extract('.element', '<div class="element">version 2</div>', reveal: true, scrollBehavior: 'smooth')
+          next =>
+            expect(@revealScrollBehavior).toEqual('auto')
+
       describe 'handling of [up-keep] elements', ->
 
         squish = (string) ->