diff --git a/pygem/__init__.py b/pygem/__init__.py
index e6aed45..3be214c 100644
--- a/pygem/__init__.py
+++ b/pygem/__init__.py
@@ -1 +1,7 @@
-__all__ = ["affine_trans", "ffd_parameters", "file_handler", "free_form"]
\ No newline at end of file
+
+__all__ = ['affine', 'params', 'filehandler', 'freeform']
+
+from . import affine
+from . import params
+from . import filehandler
+from . import freeform
\ No newline at end of file
diff --git a/pygem/affine_trans.py b/pygem/affine.py
similarity index 98%
rename from pygem/affine_trans.py
rename to pygem/affine.py
index 772f150..a7ee8b5 100644
--- a/pygem/affine_trans.py
+++ b/pygem/affine.py
@@ -21,7 +21,7 @@ def angles2matrix(rot_z=0, rot_y=0, rot_x=0):
 		
 	:Example:
 
-	>>> import pygem.affine_trans as at
+	>>> import pygem.affine as at
 	>>> import numpy as np
 
 	>>> # Example of a rotation around x, y, z axis 
@@ -118,7 +118,7 @@ def affine_points_fit(points_start, points_end):
 
 	:Example:
 
-	>>> import pygem.affine_trans as at
+	>>> import pygem.affine as at
 
 	>>> # Example of a rotation (affine transformation)
 	>>> p_start = np.array([[1,0,0], [0,1,0], [0,0,1], [0,0,0]])
diff --git a/pygem/file_handler.py b/pygem/filehandler.py
similarity index 96%
rename from pygem/file_handler.py
rename to pygem/filehandler.py
index 79a9208..774d1a6 100644
--- a/pygem/file_handler.py
+++ b/pygem/filehandler.py
@@ -1,6 +1,7 @@
 """
 Utilities for reading and writing different CAD files.
 """
+import os
 import numpy as np
 from mpl_toolkits import mplot3d
 from matplotlib import pyplot
@@ -52,7 +53,7 @@ class UnvHandler(FileHandler):
 	"""
 	def __init__(self):
 		super(UnvHandler, self).__init__()
-		self.extension = 'unv'
+		self.extension = '.unv'
 
 
 	def parse(self, filename):
@@ -155,7 +156,7 @@ class VtkHandler(FileHandler):
 	"""
 	def __init__(self):
 		super(VtkHandler, self).__init__()
-		self.extension = 'vtk'
+		self.extension = '.vtk'
 
 
 	def parse(self, filename):
@@ -215,22 +216,22 @@ def write(self, mesh_points, filename):
 		reader.ReadAllScalarsOn()
 		reader.Update()
 		data = reader.GetOutput()
-	
+
 		points = vtk.vtkPoints()
-	
+
 		for i in range(data.GetNumberOfPoints()):
-			points.InsertNextPoint(mesh_points[i,:])
-		
+			points.InsertNextPoint(mesh_points[i, :])
+
 		data.SetPoints(points)
-		
+
 		writer = vtk.vtkDataSetWriter()
 		writer.SetFileName(self.outfile)
-		
+
 		if vtk.VTK_MAJOR_VERSION <= 5:
 			writer.SetInput(data)
 		else:
 			writer.SetInputData(data)
-		
+
 		writer.Write()
 
 
@@ -242,7 +243,7 @@ class StlHandler(FileHandler):
 	"""
 	def __init__(self):
 		super(StlHandler, self).__init__()
-		self.extension = 'stl'
+		self.extension = '.stl'
 
 
 	def parse(self, filename):
@@ -423,13 +424,10 @@ def _check_extension(filename, extension):
 	:param string filename: file to check.
 	:param string extension: file extension to check.
 	"""
-	file_ext = filename.split('.')[-1].lower()
-	# to manage the case of open foam (no extension) the following check is needed
-	if file_ext == filename.lower():
-		pass
-	elif not file_ext == extension:
+	__, file_ext = os.path.splitext(filename)
+	if not file_ext == extension:
 		raise ValueError('The input file does not have the proper extension. \
-			It should be %s.' % extension)
+			It is %s, instead of %s.' % (file_ext, extension))
 
 
 def _check_filename_type(filename):
diff --git a/pygem/free_form.py b/pygem/freeform.py
similarity index 97%
rename from pygem/free_form.py
rename to pygem/freeform.py
index e987428..48d0f0a 100644
--- a/pygem/free_form.py
+++ b/pygem/freeform.py
@@ -3,7 +3,7 @@
 """
 import numpy as np
 from scipy import special
-import pygem.affine_trans as at
+import pygem.affine as at
 
 
 class FFD(object):
@@ -21,8 +21,8 @@ class FFD(object):
 
 	:Example:
 
-	>>> import pygem.free_form as ffd
-	>>> import pygem.ffd_parameters as ffdp
+	>>> import pygem.freeform as ffd
+	>>> import pygem.params as ffdp
 	>>> import numpy as np
 
 	>>> ffd_parameters = ffdp.FFDParameters()
diff --git a/pygem/ffd_parameters.py b/pygem/params.py
similarity index 99%
rename from pygem/ffd_parameters.py
rename to pygem/params.py
index c3b26d2..2654f75 100644
--- a/pygem/ffd_parameters.py
+++ b/pygem/params.py
@@ -3,7 +3,7 @@
 """
 import os
 import numpy as np
-import pygem.affine_trans as at
+import pygem.affine as at
 
 
 class FFDParameters(object):
@@ -49,7 +49,7 @@ class FFDParameters(object):
 
 	:Example:
 
-	>>> import pygem.ffd_parameters as ffdp
+	>>> import pygem.params as ffdp
 
 	>>> # Reading an existing file
 	>>> params1 = ffdp.FFDParameters()
diff --git a/tests/test_affine_trans.py b/tests/test_affine.py
similarity index 98%
rename from tests/test_affine_trans.py
rename to tests/test_affine.py
index d706534..7f6e613 100644
--- a/tests/test_affine_trans.py
+++ b/tests/test_affine.py
@@ -1,11 +1,11 @@
 
 from unittest import TestCase
 import unittest
-import pygem.affine_trans as at
+import pygem.affine as at
 import numpy as np
 
 
-class TestAffineTrans(TestCase):
+class TestAffine(TestCase):
 
 
 	def test_angles2matrix_rot_default(self):
diff --git a/tests/test_file_handler.py b/tests/test_filehandler.py
similarity index 98%
rename from tests/test_file_handler.py
rename to tests/test_filehandler.py
index 9c059a7..ab5b621 100644
--- a/tests/test_file_handler.py
+++ b/tests/test_filehandler.py
@@ -1,13 +1,13 @@
 
 from unittest import TestCase
 import unittest
-import pygem.file_handler as fh
+import pygem.filehandler as fh
 import numpy as np
 import filecmp
 import os
 
 
-class TestFileHandler(TestCase):
+class TestFilehandler(TestCase):
 
 
 	def test_base_class_infile(self):
@@ -38,7 +38,10 @@ def test_base_class_write(self):
 			file_handler.write(mesh_points, 'output')
 
 
-	# UNV tests
+
+class TestUnvHandler(TestCase):
+
+
 	def test_unv_instantiation(self):
 		unv_handler = fh.UnvHandler()
 	
@@ -55,7 +58,7 @@ def test_unv_default_outfile_member(self):
 
 	def test_unv_default_extension_member(self):
 		unv_handler = fh.UnvHandler()
-		assert unv_handler.extension == 'unv'
+		assert unv_handler.extension == '.unv'
 	
 
 	def test_unv_parse_failing_filename_type(self):
@@ -159,8 +162,11 @@ def test_unv_write_comparison(self):
 		self.assertTrue(filecmp.cmp(outfilename, outfilename_expected))
 		os.remove(outfilename)
 		
-		
-	# VTK tests
+
+
+class TestVtkHandler(TestCase):
+
+
 	def test_vtk_instantiation(self):
 		vtk_handler = fh.VtkHandler()
 	
@@ -177,7 +183,7 @@ def test_vtk_default_outfile_member(self):
 
 	def test_vtk_default_extension_member(self):
 		vtk_handler = fh.VtkHandler()
-		assert vtk_handler.extension == 'vtk'
+		assert vtk_handler.extension == '.vtk'
 	
 
 	def test_vtk_parse_failing_filename_type(self):
@@ -286,7 +292,10 @@ def test_vtk_write_comparison(self):
 		os.remove(outfilename)
 
 
-	# STL tests
+
+class TestStlHandler(TestCase):
+
+
 	def test_stl_instantiation(self):
 		stl_handler = fh.StlHandler()
 	
@@ -303,7 +312,7 @@ def test_stl_default_outfile_member(self):
 
 	def test_stl_default_extension_member(self):
 		stl_handler = fh.StlHandler()
-		assert stl_handler.extension == 'stl'
+		assert stl_handler.extension == '.stl'
 	
 
 	def test_stl_parse_failing_filename_type(self):
@@ -427,7 +436,10 @@ def test_stl_plot_failing_outfile_type(self):
 			stl_handler.plot(plot_file=3)
 			
 	
-	# openFOAM tests
+
+class TestOpenFoamHandler(TestCase):
+
+
 	def test_open_foam_instantiation(self):
 		open_foam_handler = fh.OpenFoamHandler()
 	
diff --git a/tests/test_free_form.py b/tests/test_freeform.py
similarity index 96%
rename from tests/test_free_form.py
rename to tests/test_freeform.py
index 777ba48..efafb60 100644
--- a/tests/test_free_form.py
+++ b/tests/test_freeform.py
@@ -1,13 +1,13 @@
 
 from unittest import TestCase
 import unittest
-import pygem.free_form as ffd
-import pygem.ffd_parameters as ffdp
+import pygem.freeform as ffd
+import pygem.params as ffdp
 import numpy as np
 
 
 
-class TestFFD(TestCase):
+class TestFreeform(TestCase):
 
 
 	def test_ffd_parameters_member(self):
diff --git a/tests/test_package.py b/tests/test_package.py
new file mode 100644
index 0000000..c2601d7
--- /dev/null
+++ b/tests/test_package.py
@@ -0,0 +1,39 @@
+
+from unittest import TestCase
+import unittest
+import pkgutil
+from os import walk
+from os import path
+
+
+class TestPackage(TestCase):
+
+
+	def test_modules_name(self):
+		import pygem
+		package = pygem
+		mod = ['__init__.py']
+		for __, modname, __ in pkgutil.iter_modules(package.__path__):
+			mod.append(modname + '.py')
+		
+		f_aux = []
+		for (__, __, filenames) in walk('pygem'):
+			f_aux.extend(filenames)
+
+		f = []
+		for i in f_aux:
+			__, file_ext = path.splitext(i)
+			if file_ext == '.py':
+				f.append(i)
+					
+		self.assertItemsEqual(mod, f)
+
+
+	def test_import_pg_1(self):
+		import pygem as pg
+		params = pg.params.FFDParameters()
+
+
+	def test_import_pg_2(self):
+		import pygem as pg
+		mat = pg.affine.angles2matrix(2)
\ No newline at end of file
diff --git a/tests/test_ffd_parameters.py b/tests/test_params.py
similarity index 99%
rename from tests/test_ffd_parameters.py
rename to tests/test_params.py
index 11000bb..b2f2f37 100644
--- a/tests/test_ffd_parameters.py
+++ b/tests/test_params.py
@@ -1,7 +1,7 @@
 
 from unittest import TestCase
 import unittest
-import pygem.ffd_parameters as ffdp
+import pygem.params as ffdp
 import numpy as np
 import filecmp
 import os