added GridFileNotFound and GridMD5Failure exceptions

lib/mongo/exceptions.rb

@@ -27,6 +27,12 @@ module Mongo
   # Raised on fatal errors to GridFS.
   class GridError < MongoRubyError; end
 
+  # Raised on fatal errors to GridFS.
+  class GridFileNotFound < GridError; end
+
+  # Raised on fatal errors to GridFS.
+  class GridMD5Failure < GridError; end
+
   # Raised when invalid arguments are sent to Mongo Ruby methods.
   class MongoArgumentError < MongoRubyError; end
 

lib/mongo/gridfs/grid_io.rb

@@ -287,7 +287,7 @@ module Mongo
     # Initialize the class for reading a file.
     def init_read
       doc = @files.find(@query, @query_opts).next_document
-      raise GridError, "Could not open file matching #{@query.inspect} #{@query_opts.inspect}" unless doc
+      raise GridFileNotFound, "Could not open file matching #{@query.inspect} #{@query_opts.inspect}" unless doc
 
       @files_id     = doc['_id']
       @content_type = doc['contentType']
@@ -342,7 +342,7 @@ module Mongo
       if @safe
         @client_md5 = @local_md5.hexdigest
         if @local_md5 != @server_md5
-          raise GridError, "File on server failed MD5 check"
+          raise GridMD5Failure, "File on server failed MD5 check"
         end
       else
         @server_md5

test/grid_file_system_test.rb

@@ -75,9 +75,15 @@ class GridFileSystemTest < Test::Unit::TestCase
        assert_equal data.length, @data.length
      end
 
+     should "raise exception if file not found" do
+       assert_raise GridFileNotFound do
+         @grid.open('io', 'r') { |f| f.write('hello') }
+       end
+     end
+
      should "raise exception if not opened for write" do
        assert_raise GridError do
-         @grid.open('io', 'r') { |f| f.write('hello') }
+         @grid.open('sample', 'r') { |f| f.write('hello') }
        end
      end
 

test/grid_io_test.rb

@@ -49,6 +49,19 @@ class GridIOTest < Test::Unit::TestCase
         assert file.close
         assert_equal file.server_md5, file.client_md5
       end
+
+      should "raise an exception when check fails" do
+        io = File.open(File.join(File.dirname(__FILE__), 'data', 'sample_file.pdf'), 'r')
+        db = mock()
+        db.stubs(:command).returns({'md5' => '12345'})
+        @files.expects(:db).returns(db)
+        file = GridIO.new(@files, @chunks, 'bigfile', 'w', :safe => true)
+        file.write(io)
+        assert_raise GridMD5Failure do
+          assert file.close
+        end
+        assert_not_equal file.server_md5, file.client_md5
+      end
     end
 
     context "Content types" do

test/grid_test.rb

@@ -39,7 +39,7 @@ class GridTest < Test::Unit::TestCase
 
       should "delete the file and any chunks" do
         @grid.delete(@id)
-        assert_raise GridError do
+        assert_raise GridFileNotFound do
           @grid.get(@id)
         end
         assert_equal nil, @db['test-fs']['chunks'].find_one({:files_id => @id})