Bust that cache

lib/linguist/repository.rb

@@ -1,6 +1,6 @@
 require 'linguist/lazy_blob'
 require 'rugged'
-
+require 'pry'
 module Linguist
   # A Repository is an abstraction of a Grit::Repo or a basic file
   # system tree. It holds a list of paths pointing to Blobish objects.
@@ -128,13 +128,23 @@ module Linguist
     protected
 
     def compute_stats(old_commit_oid, cache = nil)
-      file_map = cache ? cache.dup : {}
       old_tree = old_commit_oid && Rugged::Commit.lookup(repository, old_commit_oid).tree
 
       read_index
 
       diff = Rugged::Tree.diff(repository, old_tree, current_tree)
 
+      # Clear file map and fetch full diff if any .gitattributes files are changed
+      if cache && diff.each_delta.any? { |delta| File.basename(delta.new_file[:path]) == ".gitattributes" }
+        diff = Rugged::Tree.diff(repository, old_tree = nil, current_tree)
+        file_map = {}
+      else
+        file_map = cache ? cache.dup : {}
+      end
+
+      # TODO - do we need to re-read the index?
+      # read_index
+
       diff.each_delta do |delta|
         old = delta.old_file[:path]
         new = delta.new_file[:path]

test/test_repository.rb

@@ -68,6 +68,18 @@ class TestRepository < Test::Unit::TestCase
     assert !repo.breakdown_by_file["Ruby"].empty?
   end
 
+  def test_commit_with_git_attributes_data
+    old_commit = '3d7364877d6794f6cc2a86b493e893968a597332'
+    old_repo = linguist_repo(old_commit)
+
+    attr_commit = '7ee006cbcb2d7261f9e648510a684ee9ac64126b'
+    new_repo = Linguist::Repository.incremental(rugged_repository, attr_commit, old_commit, old_repo.cache)
+
+    Rugged::Tree.expects(:diff).twice
+
+    new_repo.send(:compute_stats, old_commit, old_repo.cache)
+  end
+
   def test_linguist_override_vendored?
     attr_commit = '351c1cc8fd57340839bdb400d7812332af80e9bd'
     repo = linguist_repo(attr_commit).read_index