Set _file_ and _line_ when calling whereami.

When a user would place a call to `binding.pry` followed by calling `whereami`
the locals _file_ and _line_ would not be set properly. This commit fixes this
by using the helper method `set_file_and_dir_locals()` (which also ensures _dir_
is set properly) as well as `_pry_.inject_local`.

Currently the _file_ local is set to /path/to/your/directory/(pry) if the
binding was set in a Pry session itself. I'm not entirely sure if this is
expected behavior, if this isn't the case it shouldn't be too hard to detect and
fix in a following commit.

This commit fixes #574.

Signed-off-by: Yorick Peterse <yorickpeterse@gmail.com>

lib/pry/default_commands/context.rb

@@ -48,6 +48,9 @@ class Pry
           desc = (@method && @method.name_with_owner) || ""
 
           if !code.empty?
+            set_file_and_dir_locals(file)
+            _pry_.inject_local('_line_', start, target)
+
             output.puts "\n#{text.bold('From:')} #{file} @ line #{start} #{desc}:\n\n"
             output.puts code.with_line_numbers.with_marker(marker)
             output.puts

test/test_default_commands/test_context.rb

@@ -56,6 +56,20 @@ describe "Pry::DefaultCommands::Context" do
       Cor.new.blimey!
       Object.remove_const(:Cor)
     end
+
+    it 'should properly set _file_, _line_ and _dir_' do
+      class Cor
+        def blimey!
+          mock_pry(binding, 'whereami', '_file_') \
+            .should =~ /#{File.expand_path(__FILE__)}/
+
+          mock_pry(binding, 'whereami', '_line_').should =~ /#{__LINE__}/
+        end
+      end
+
+      Cor.new.blimey!
+      Object.remove_const(:Cor)
+    end
   end
 
   describe "exit" do
@@ -160,9 +174,9 @@ describe "Pry::DefaultCommands::Context" do
     end
 
     it "should not leave the REPL session when given 'cd ..'" do
-      b = Pry.binding_for(Object.new) 
-      input = InputTester.new "cd ..", "$obj = self", "exit-all" 
-      
+      b = Pry.binding_for(Object.new)
+      input = InputTester.new "cd ..", "$obj = self", "exit-all"
+
       redirect_pry_io(input, StringIO.new) do
         b.pry
       end