Merge branch 'stable' into beta

spec/fake-lines-yardstick.coffee

@@ -7,6 +7,7 @@ class FakeLinesYardstick
 
   prepareScreenRowsForMeasurement: ->
     @presenter.getPreMeasurementState()
+    @screenRows = new Set(@presenter.getScreenRows())
 
   getScopedCharacterWidth: (scopeNames, char) ->
     @getScopedCharacterWidths(scopeNames)[char]
@@ -34,6 +35,8 @@ class FakeLinesYardstick
     left = 0
     column = 0
 
+    return {top, left: 0} unless @screenRows.has(screenPosition.row)
+
     iterator = @model.tokenizedLineForScreenRow(targetRow).getTokenIterator()
     while iterator.next()
       characterWidths = @getScopedCharacterWidths(iterator.getScopes())

spec/text-editor-presenter-spec.coffee

@@ -694,6 +694,20 @@ describe "TextEditorPresenter", ->
           presenter = buildPresenter(explicitHeight: 100, contentFrameWidth: 10 * maxLineLength + 20, baseCharacterWidth: 10, verticalScrollbarWidth: 10)
           expect(presenter.getState().content.scrollWidth).toBe 10 * maxLineLength + 20 - 10 # subtract vertical scrollbar width
 
+        describe "when the longest screen row is the first one and it's hidden", ->
+          it "doesn't compute an invalid value (regression)", ->
+            presenter = buildPresenter(tileSize: 2, contentFrameWidth: 10, explicitHeight: 20)
+            editor.setText """
+            a very long long long long long long line
+            b
+            c
+            d
+            e
+            """
+
+            expectStateUpdate presenter, -> presenter.setScrollTop(40)
+            expect(presenter.getState().content.scrollWidth).toBe 10 * editor.getMaxScreenLineLength() + 1
+
         it "updates when the ::contentFrameWidth changes", ->
           maxLineLength = editor.getMaxScreenLineLength()
           presenter = buildPresenter(contentFrameWidth: 50, baseCharacterWidth: 10)

src/text-editor-presenter.coffee

@@ -377,7 +377,8 @@ class TextEditorPresenter
     endRow = @constrainRow(@getEndTileRow() + @tileSize)
 
     screenRows = [startRow...endRow]
-    if longestScreenRow = @model.getLongestScreenRow()
+    longestScreenRow = @model.getLongestScreenRow()
+    if longestScreenRow?
       screenRows.push(longestScreenRow)
     if @screenRowsToMeasure?
       screenRows.push(@screenRowsToMeasure...)