diff --git a/tardis/conftest.py b/tardis/conftest.py
index 5eabacc395e..13f6cd84027 100644
--- a/tardis/conftest.py
+++ b/tardis/conftest.py
@@ -12,6 +12,8 @@
 from tardis.atomic import AtomData
 from tardis.io.config_reader import Configuration
 from tardis.io.util import yaml_load_config_file
+from tardis.model import Radial1DModel
+from tardis.model.density import HomologousDensity
 
 ###
 # Astropy
@@ -117,3 +119,29 @@ def included_he_atomic_data(test_data_path):
 def tardis_config_verysimple():
     return yaml_load_config_file(
         'tardis/io/tests/data/tardis_configv1_verysimple.yml')
+
+###
+# HDF Fixtures
+###
+
+@pytest.fixture(scope="session")
+def hdf_file_path(tmpdir_factory):
+    path = tmpdir_factory.mktemp('hdf_buffer').join('test.hdf')
+    return str(path)
+
+@pytest.fixture(scope="session")
+def hdf_config():
+    filename = 'tardis_configv1_verysimple.yml'
+    path = os.path.abspath(os.path.join('tardis/io/tests/data/', filename))
+    config = Configuration.from_yaml(path)
+    return config
+
+@pytest.fixture(scope="session")
+def model(hdf_config):
+    model = Radial1DModel.from_config(hdf_config)
+    return model
+
+@pytest.fixture(scope="session")
+def homologous_density(hdf_config):
+    density =  HomologousDensity.from_config(hdf_config)
+    return density
\ No newline at end of file
diff --git a/tardis/model/base.py b/tardis/model/base.py
index 03ed6401184..f35306e53a7 100644
--- a/tardis/model/base.py
+++ b/tardis/model/base.py
@@ -6,13 +6,13 @@
 
 from tardis.util import quantity_linspace, element_symbol2atomic_number
 from tardis.io.model_reader import read_density_file, read_abundances_file
-from tardis.io.util import HDFWriter
+from tardis.io.util import HDFWriter as HDFWriterMixin
 from density import HomologousDensity
 
 logger = logging.getLogger(__name__)
 
 
-class Radial1DModel(HDFWriter, object):
+class Radial1DModel(HDFWriterMixin):
     """An object that hold information about the individual shells.
 
     Parameters
diff --git a/tardis/model/density.py b/tardis/model/density.py
index 4f172c9eea3..4bad6e5abeb 100644
--- a/tardis/model/density.py
+++ b/tardis/model/density.py
@@ -1,9 +1,9 @@
 import numpy as np
 
 from tardis.util import quantity_linspace
-from tardis.io.util import HDFWriter
+from tardis.io.util import HDFWriter as HDFWriterMixin
 
-class HomologousDensity(HDFWriter, object):
+class HomologousDensity(HDFWriterMixin):
     """A class that holds an initial density and time
 
     Parameters
diff --git a/tardis/model/tests/test_base.py b/tardis/model/tests/test_base.py
index 155609f9552..83b67ec674b 100644
--- a/tardis/model/tests/test_base.py
+++ b/tardis/model/tests/test_base.py
@@ -209,32 +209,17 @@ def test_ascii_reader_exponential_law():
 # Save and Load
 ###
 
-
-@pytest.fixture(scope="module")
-def hdf_file_path(tmpdir_factory):
-    path = tmpdir_factory.mktemp('hdf_buffer').join('model.hdf')
-    return str(path)
-
-
-@pytest.fixture(scope="module")
-def actual_model():
-    filename = 'tardis_configv1_verysimple.yml'
-    config = Configuration.from_yaml(data_path(filename))
-    model = Radial1DModel.from_config(config)
-    return model
-
-
 @pytest.fixture(scope="module", autouse=True)
-def to_hdf_buffer(hdf_file_path, actual_model):
-    actual_model.to_hdf(hdf_file_path)
+def to_hdf_buffer(hdf_file_path, model):
+    model.to_hdf(hdf_file_path)
 
 model_scalar_attrs = ['t_inner']
 
 @pytest.mark.parametrize("attr", model_scalar_attrs)
-def test_hdf_model_scalars(hdf_file_path, actual_model, attr):
+def test_hdf_model_scalars(hdf_file_path, model, attr):
     path = os.path.join('model', 'scalars')
     expected = pd.read_hdf(hdf_file_path, path)[attr]
-    actual = getattr(actual_model, attr)
+    actual = getattr(model, attr)
     if hasattr(actual, 'cgs'):
         actual = actual.cgs.value
     assert_almost_equal(actual, expected)
@@ -242,10 +227,10 @@ def test_hdf_model_scalars(hdf_file_path, actual_model, attr):
 model_nparray_attrs = ['w', 'v_inner', 'v_outer']
 
 @pytest.mark.parametrize("attr", model_nparray_attrs)
-def test_hdf_model_nparray(hdf_file_path, actual_model, attr):
+def test_hdf_model_nparray(hdf_file_path, model, attr):
     path = os.path.join('model', attr)
     expected = pd.read_hdf(hdf_file_path, path)
-    actual = getattr(actual_model, attr)
+    actual = getattr(model, attr)
     if hasattr(actual, 'cgs'):
         actual = actual.cgs.value
     assert_almost_equal(actual, expected.values)
diff --git a/tardis/model/tests/test_density.py b/tardis/model/tests/test_density.py
index f30dab81418..c1721cb514d 100644
--- a/tardis/model/tests/test_density.py
+++ b/tardis/model/tests/test_density.py
@@ -3,30 +3,11 @@
 import pytest
 from numpy.testing import assert_almost_equal
 
-from tardis.io.config_reader import Configuration
-from tardis.model.density import HomologousDensity
-
-
 ###
 # Save and Load
 ###
 
-def data_path(filename):
-    return os.path.join('tardis/io/tests/data/', filename)
-
-@pytest.fixture(scope="module")
-def hdf_file_path(tmpdir_factory):
-    path = tmpdir_factory.mktemp('hdf_buffer').join('density.hdf')
-    return str(path)
-
-@pytest.fixture(scope="module")
-def homologous_density():
-    filename = 'tardis_configv1_verysimple.yml'
-    config = Configuration.from_yaml(data_path(filename)) 
-    density =  HomologousDensity.from_config(config)
-    return density
-
-@pytest.fixture(scope="module",autouse=True)
+@pytest.fixture(scope="module", autouse=True)
 def to_hdf_buffer(hdf_file_path,homologous_density):
     homologous_density.to_hdf(hdf_file_path)