SpanIndex.spanForIndex returns span of elements up to and *including* index.

spec/atom/span-index-spec.coffee

@@ -22,11 +22,11 @@ describe "SpanIndex", ->
     it "updates the spans of a range of entries indicated by the given index to the given value", ->
       index.insert(0, [3, 2, 3, 1, 2], ['a', 'b', 'c', 'd', 'e'])
       index.updateSpans(1, 3, 1)
-      expect(index.spanForIndex(1)).toBe 3
-      expect(index.spanForIndex(2)).toBe 4
-      expect(index.spanForIndex(3)).toBe 5
-      expect(index.spanForIndex(4)).toBe 6
-      expect(index.spanForIndex(5)).toBe 8
+      expect(index.spanForIndex(0)).toBe 3
+      expect(index.spanForIndex(1)).toBe 4
+      expect(index.spanForIndex(2)).toBe 5
+      expect(index.spanForIndex(3)).toBe 6
+      expect(index.spanForIndex(4)).toBe 8
 
   describe ".sliceBySpan(start, end)", ->
     describe "when the index contains values that start and end evenly on the given start/end span indices", ->
@@ -85,12 +85,13 @@ describe "SpanIndex", ->
       expect(index.indexForSpan(5)).toEqual(index: 3, offset: 0)
 
   describe ".spanForIndex(index)", ->
-    it "returns the aggregate of spans for elements preceding the given index", ->
+    it "returns the aggregate of spans for all elements up to and including the given index", ->
       index.insert(0, [3, 0, 2, 0, 3, 1], ['a', 'b', 'c', 'd', 'e', 'f'])
-      expect(index.spanForIndex(0)).toBe 0
+      expect(index.spanForIndex(0)).toBe 3
       expect(index.spanForIndex(1)).toBe 3
-      expect(index.spanForIndex(2)).toBe 3
+      expect(index.spanForIndex(2)).toBe 5
       expect(index.spanForIndex(3)).toBe 5
+      expect(index.spanForIndex(4)).toBe 8
 
 
 

src/atom/line-wrapper.coffee

@@ -91,10 +91,10 @@ class LineWrapper
 
   screenPositionFromBufferPosition: (bufferPosition, allowEOL=false) ->
     bufferPosition = Point.fromObject(bufferPosition)
-    row = @index.spanForIndex(bufferPosition.row)
+    screenLines = @index.at(bufferPosition.row).screenLines
+    row = @index.spanForIndex(bufferPosition.row) - screenLines.length
     column = bufferPosition.column
 
-    screenLines = @index.at(bufferPosition.row).screenLines
     for screenLine, index in screenLines
       break if index == screenLines.length - 1
       if allowEOL

src/atom/span-index.coffee

@@ -66,7 +66,7 @@ class SpanIndex
 
   spanForIndex: (index) ->
     span = 0
-    for i in [0...index]
+    for i in [0..index]
       span += @entries[i].span
     span