diff --git a/tardis/io/configuration/tests/test_config_reader.py b/tardis/io/configuration/tests/test_config_reader.py
index 8c5639b31a0..f525557ca63 100644
--- a/tardis/io/configuration/tests/test_config_reader.py
+++ b/tardis/io/configuration/tests/test_config_reader.py
@@ -195,9 +195,7 @@ def test_plasma_nlte_section_root_config(
     ] = [
         "He I",
     ]
-    tardis_config_verysimple_nlte["plasma"]["nlte_ionization_species"] = [
-        "H I"
-    ]
+    tardis_config_verysimple_nlte["plasma"]["nlte_ionization_species"] = ["H I"]
     config = Configuration.from_config_dict(tardis_config_verysimple_nlte)
     with pytest.raises(PlasmaConfigError) as ve:
         assemble_plasma(config, nlte_raw_model_root, nlte_atom_data)
@@ -229,9 +227,7 @@ def test_plasma_nlte_section_lu_config(
     ] = [
         "He I",
     ]
-    tardis_config_verysimple_nlte["plasma"]["nlte_ionization_species"] = [
-        "H I"
-    ]
+    tardis_config_verysimple_nlte["plasma"]["nlte_ionization_species"] = ["H I"]
     tardis_config_verysimple_nlte["plasma"]["nlte_solver"] = "lu"
     config = Configuration.from_config_dict(tardis_config_verysimple_nlte)
     with pytest.raises(PlasmaConfigError) as ve:
@@ -262,9 +258,7 @@ def test_plasma_nlte_root_exc_section_config(
     ] = [
         "He I",
     ]
-    tardis_config_verysimple_nlte["plasma"]["nlte_excitation_species"] = [
-        "H I"
-    ]
+    tardis_config_verysimple_nlte["plasma"]["nlte_excitation_species"] = ["H I"]
     tardis_config_verysimple_nlte["plasma"]["nlte_solver"] = "root"
     config = Configuration.from_config_dict(tardis_config_verysimple_nlte)
     with pytest.raises(PlasmaConfigError):
diff --git a/tardis/plasma/tests/test_nlte_solver.py b/tardis/plasma/tests/test_nlte_solver.py
index 0f060064f30..29b9db456cb 100644
--- a/tardis/plasma/tests/test_nlte_solver.py
+++ b/tardis/plasma/tests/test_nlte_solver.py
@@ -283,9 +283,13 @@ def nlte_raw_plasma_dilution_factor_0_lu(
 # vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv #
 ###############################################################################
 @pytest.mark.xfail
-def test_critical_case_dilution_factor_1_root(nlte_raw_plasma_dilution_factor_1):
+def test_critical_case_dilution_factor_1_root(
+    nlte_raw_plasma_dilution_factor_1,
+):
     """Check that the LTE and NLTE solution agree for dilution_factor=1.0."""
-    ion_number_density_nlte = nlte_raw_plasma_dilution_factor_1_root.ion_number_density.values
+    ion_number_density_nlte = (
+        nlte_raw_plasma_dilution_factor_1_root.ion_number_density.values
+    )
     ion_number_density_nlte[np.abs(ion_number_density_nlte) < 1e-10] = 0.0
 
     ind = IonNumberDensity(nlte_raw_plasma_dilution_factor_1_root)
@@ -309,7 +313,9 @@ def test_critical_case_dilution_factor_1_root(nlte_raw_plasma_dilution_factor_1)
 @pytest.mark.xfail
 def test_critical_case_dilution_factor_1_lu(nlte_raw_plasma_dilution_factor_1):
     """Check that the LTE and NLTE solution agree for dilution_factor=1.0."""
-    ion_number_density_nlte = nlte_raw_plasma_dilution_factor_1_lu.ion_number_density.values
+    ion_number_density_nlte = (
+        nlte_raw_plasma_dilution_factor_1_lu.ion_number_density.values
+    )
     ion_number_density_nlte[np.abs(ion_number_density_nlte) < 1e-10] = 0.0
 
     ind = IonNumberDensity(nlte_raw_plasma_dilution_factor_1_lu)
@@ -331,9 +337,13 @@ def test_critical_case_dilution_factor_1_lu(nlte_raw_plasma_dilution_factor_1):
 
 
 @pytest.mark.xfail
-def test_critical_case_dilution_factor_0_root(nlte_raw_plasma_dilution_factor_0_root):
+def test_critical_case_dilution_factor_0_root(
+    nlte_raw_plasma_dilution_factor_0_root,
+):
     """Check that the LTE and NLTE solution agree for dilution_factor=0.0."""
-    nlte_solver = NLTEPopulationSolverRoot(nlte_raw_plasma_dilution_factor_0_root)
+    nlte_solver = NLTEPopulationSolverRoot(
+        nlte_raw_plasma_dilution_factor_0_root
+    )
     ion_number_density_nlte = nlte_solver.calculate(
         nlte_raw_plasma_dilution_factor_0_root.gamma,
         0.0,  # to test collisions only, we set the radiative recombination rate to 0
@@ -370,7 +380,9 @@ def test_critical_case_dilution_factor_0_root(nlte_raw_plasma_dilution_factor_0_
 
 
 @pytest.mark.xfail
-def test_critical_case_dilution_factor_0_lu(nlte_raw_plasma_dilution_factor_0_lu):
+def test_critical_case_dilution_factor_0_lu(
+    nlte_raw_plasma_dilution_factor_0_lu,
+):
     """Check that the LTE and NLTE solution agree for dilution_factor=0.0."""
     nlte_solver = NLTEPopulationSolverLU(nlte_raw_plasma_dilution_factor_0_lu)
     ion_number_density_nlte = nlte_solver.calculate(
diff --git a/tardis/tests/fixtures/atom_data.py b/tardis/tests/fixtures/atom_data.py
index 11b8676d847..500552e4b9c 100644
--- a/tardis/tests/fixtures/atom_data.py
+++ b/tardis/tests/fixtures/atom_data.py
@@ -1,5 +1,5 @@
 from copy import deepcopy
-from pathlib import Path 
+from pathlib import Path
 import pytest
 
 from tardis.io.atom_data.base import AtomData
@@ -97,6 +97,7 @@ def tardis_model_config_nlte_lu(example_configuration_dir):
 def nlte_raw_model_root(tardis_model_config_nlte_root):
     return SimulationState.from_config(tardis_model_config_nlte_root)
 
+
 @pytest.fixture  # (scope="session")
 def nlte_raw_model_lu(tardis_model_config_nlte_lu):
     return SimulationState.from_config(tardis_model_config_nlte_lu)