Make sure block decorations are always in the right spot

spec/text-editor-component-spec.js

@@ -1663,7 +1663,7 @@ describe('TextEditorComponent', function () {
       atom.themes.removeStylesheet('test')
     })
 
-    it("renders visible and yet-to-be-measured block decorations, inserting them in the appropriate spots between lines and refreshing them when needed", async function () {
+    it("renders visible and yet-to-be-measured block decorations, inserting them between the appropriate lines and refreshing them as needed", async function () {
       wrapperNode.style.height = 9 * lineHeightInPixels + 'px'
       component.measureDimensions()
       await nextViewUpdatePromise()

spec/text-editor-presenter-spec.coffee

@@ -1320,11 +1320,11 @@ describe "TextEditorPresenter", ->
                 expect(lineStateForScreenRow(presenter, 12).blockDecorations).toEqual([])
 
               waitsForStateToUpdate presenter, ->
-                blockDecoration1.destroy()
                 blockDecoration3.destroy()
+                blockDecoration1.getMarker().setHeadBufferPosition([0, 0])
 
               runs ->
-                expect(lineStateForScreenRow(presenter, 0).blockDecorations).toEqual([])
+                expect(lineStateForScreenRow(presenter, 0).blockDecorations).toEqual([blockDecoration1])
                 expect(lineStateForScreenRow(presenter, 1).blockDecorations).toEqual([])
                 expect(lineStateForScreenRow(presenter, 2).blockDecorations).toEqual([])
                 expect(lineStateForScreenRow(presenter, 3).blockDecorations).toEqual([])
@@ -1338,6 +1338,25 @@ describe "TextEditorPresenter", ->
                 expect(lineStateForScreenRow(presenter, 11).blockDecorations).toEqual([])
                 expect(lineStateForScreenRow(presenter, 12).blockDecorations).toEqual([])
 
+              waitsForStateToUpdate presenter, ->
+                editor.setCursorBufferPosition([0, 0])
+                editor.insertNewline()
+
+              runs ->
+                expect(lineStateForScreenRow(presenter, 0).blockDecorations).toEqual([])
+                expect(lineStateForScreenRow(presenter, 1).blockDecorations).toEqual([blockDecoration1])
+                expect(lineStateForScreenRow(presenter, 2).blockDecorations).toEqual([])
+                expect(lineStateForScreenRow(presenter, 3).blockDecorations).toEqual([])
+                expect(lineStateForScreenRow(presenter, 4).blockDecorations).toEqual([])
+                expect(lineStateForScreenRow(presenter, 5).blockDecorations).toEqual([])
+                expect(lineStateForScreenRow(presenter, 6).blockDecorations).toEqual([])
+                expect(lineStateForScreenRow(presenter, 7).blockDecorations).toEqual([])
+                expect(lineStateForScreenRow(presenter, 8).blockDecorations).toEqual([])
+                expect(lineStateForScreenRow(presenter, 9).blockDecorations).toEqual([])
+                expect(lineStateForScreenRow(presenter, 10).blockDecorations).toEqual([blockDecoration2])
+                expect(lineStateForScreenRow(presenter, 11).blockDecorations).toEqual([])
+                expect(lineStateForScreenRow(presenter, 12).blockDecorations).toEqual([])
+
           describe ".decorationClasses", ->
             it "adds decoration classes to the relevant line state objects, both initially and when decorations change", ->
               marker1 = editor.addMarkerLayer(maintainHistory: true).markBufferRange([[4, 0], [6, 2]], invalidate: 'touch')
@@ -1551,10 +1570,11 @@ describe "TextEditorPresenter", ->
 
           blockDecoration1 = editor.addBlockDecorationForScreenRow(0)
           blockDecoration2 = editor.addBlockDecorationForScreenRow(1)
-          presenter.setBlockDecorationDimensions(blockDecoration1, 0, 30)
-          presenter.setBlockDecorationDimensions(blockDecoration2, 0, 10)
 
-          waitsForStateToUpdate presenter
+          waitsForStateToUpdate presenter, ->
+            presenter.setBlockDecorationDimensions(blockDecoration1, 0, 30)
+            presenter.setBlockDecorationDimensions(blockDecoration2, 0, 10)
+
           runs ->
             expect(stateForCursor(presenter, 0)).toEqual {top: 50, left: 2 * 10, width: 10, height: 10}
             expect(stateForCursor(presenter, 1)).toEqual {top: 60, left: 4 * 10, width: 10, height: 10}
@@ -1562,6 +1582,15 @@ describe "TextEditorPresenter", ->
             expect(stateForCursor(presenter, 3)).toBeUndefined()
             expect(stateForCursor(presenter, 4)).toBeUndefined()
 
+          waitsForStateToUpdate presenter, ->
+            blockDecoration2.destroy()
+            editor.setCursorBufferPosition([0, 0])
+            editor.insertNewline()
+            editor.setCursorBufferPosition([0, 0])
+
+          runs ->
+            expect(stateForCursor(presenter, 0)).toEqual {top: 0, left: 0, width: 10, height: 10}
+
         it "updates when ::scrollTop changes", ->
           editor.setSelectedBufferRanges([
             [[1, 2], [1, 2]],

src/lines-tile-component.coffee

@@ -127,14 +127,14 @@ class LinesTileComponent
       delete @insertionPointsByLineId[id]
 
   insertBlockDecorationInsertionPoint: (id) ->
-    {hasBlockDecorations} = @newTileState.lines[id]
+    {hasBlockDecorations, screenRow} = @newTileState.lines[id]
 
     if hasBlockDecorations
       lineNode = @lineNodesByLineId[id]
       insertionPoint = @domElementPool.buildElement("content")
       @domNode.insertBefore(insertionPoint, lineNode)
       @insertionPointsByLineId[id] = insertionPoint
-
+      insertionPoint.dataset.screenRow = screenRow
       @updateBlockDecorationInsertionPoint(id)
 
   updateBlockDecorationInsertionPoint: (id) ->