Merge pull request #611 from Insti/Example_file_location_bugfix

tests: Check in the correct location for the example file.

Author: hilary

lib/tasks/exercise.rb

@@ -23,7 +23,7 @@ def directory
   end
 
   def example_file
-    File.exist?(example_filename) ? example_filename : legacy_example_filename
+    File.exist?(File.join(directory, example_filename)) ? example_filename : legacy_example_filename
   end
 
   def testable_example_file

test/tasks/exercise_test.rb

@@ -31,8 +31,10 @@ def test_directory
   end
 
   def test_example_file
-    File.stub(:exist?, true) do
-      assert_equal '.meta/solutions/name.rb', Exercise.new('name').example_file
+    mock_exist = Minitest::Mock.new
+    mock_exist.expect(:call, true, ['exercises/alpha/./.meta/solutions/alpha.rb'])
+    File.stub(:exist?, mock_exist) do
+      assert_equal '.meta/solutions/alpha.rb', Exercise.new('alpha').example_file
     end
   end