store the last selected line and use it as the other end for multiple selection

assets/scripts/lib/travis/lines_selector.coffee

@@ -2,9 +2,11 @@ class Travis.LinesSelector
   element: null
   scroll: null
   location: null
+  last_selected_line: null
 
   constructor: (@element, @scroll, @location) ->
     Ember.run.scheduleOnce 'afterRender', this, ->
+      @last_selected_line = @getSelectedLines()?.first
       @highlightLines()
 
     @element.on 'click', 'a', (event) =>
@@ -25,19 +27,19 @@ class Travis.LinesSelector
     @removeAllHighlights()
 
     if lines = @getSelectedLines()
-      @element.find('p:visible').slice(lines.first, lines.last).addClass('highlight')
+      @element.find('p:visible').slice(lines.first - 1, lines.last).addClass('highlight')
     @scroll.tryScroll()
 
   setHashValueWithLine: (line, multiple) ->
     line_number = @getLineNumberFromElement(line)
 
-    if !multiple
+    if multiple && @last_selected_line?
-      hash = "#L#{line_number}"
+      lines = [line_number, @last_selected_line].sort (a,b) -> a - b
-    else
-      selected_line = @element.find('p:visible.highlight:first')[0]
-      selected_number = @getLineNumberFromElement(selected_line)
-      lines = [line_number, selected_number].sort (a,b) -> a - b
       hash = "#L#{lines[0]}-L#{lines[1]}"
+    else
+      hash = "#L#{line_number}"
+
+    @last_selected_line = line_number
     @location.hash = hash
 
   getLineNumberFromElement: (element) ->
@@ -48,6 +50,6 @@ class Travis.LinesSelector
 
   getSelectedLines: ->
     if match = @location.hash.match(/#L(\d+)(-L(\d+))?$/)
-      first = match[1] - 1
+      first = match[1]
       last = match[3] || match[1]
       {first: first, last: last}

assets/scripts/spec/unit/line_selector_spec.coffee

@@ -57,6 +57,7 @@ test "selects multiple lines", ->
   fakeLocation.hash = '#L2'
   Ember.run ->
     new Travis.LinesSelector(element, fakeScroll, fakeLocation)
+
   wait().then ->
     equal($('#fakeLog p.highlight').length, 1)
 
@@ -68,3 +69,24 @@ test "selects multiple lines", ->
     equal($('#fakeLog p:nth-child(1)').hasClass('highlight'), true)
     equal($('#fakeLog p:nth-child(2)').hasClass('highlight'), true)
     equal('#L1-L2', fakeLocation.hash)
+
+test "uses the last selected line as second selection line", ->
+  selector = null
+  Ember.run ->
+    selector = new Travis.LinesSelector(element, fakeScroll, fakeLocation)
+
+  wait().then ->
+    $('#fakeLog p:last a').click()
+    equal($('#fakeLog p.highlight').length, 1)
+    equal(3, selector.last_selected_line)
+
+    event = jQuery.Event('click')
+    event.shiftKey = true
+    $('#fakeLog p:first a').trigger(event)
+
+    equal($('#fakeLog p.highlight').length, 3)
+    equal($('#fakeLog p:nth-child(1)').hasClass('highlight'), true)
+    equal($('#fakeLog p:nth-child(2)').hasClass('highlight'), true)
+    equal($('#fakeLog p:nth-child(3)').hasClass('highlight'), true)
+    equal('#L1-L3', fakeLocation.hash)
+    equal(1, selector.last_selected_line)