diff --git a/tests/fba/algorithm/test_fba.py b/tests/fba/algorithm/test_fba.py
index fcfe4b7..47636b3 100644
--- a/tests/fba/algorithm/test_fba.py
+++ b/tests/fba/algorithm/test_fba.py
@@ -37,7 +37,7 @@ def test_rank_to_partition_idx(rank, expected):
     ),
 )
 def test_build_block_counterimage(graph, counterimaged_block_indexes):
-    vertexes, _ = prepare_graph(graph)
+    vertexes = prepare_graph(graph)
     counterimaged_block = _Block(
         map(lambda idx: vertexes[idx], counterimaged_block_indexes), None
     )
@@ -59,35 +59,16 @@ def test_build_block_counterimage(graph, counterimaged_block_indexes):
         )
 
 
-@pytest.mark.parametrize(
-    "graph",
-    test_cases.graphs,
-)
-def test_prepare_graph_max_rank(graph):
-    _, max_rank = prepare_graph(graph)
-    assert max_rank == max(
-        map(lambda node: graph.nodes[node]["rank"], graph.nodes)
-    )
-
-
 @pytest.mark.parametrize(
     "graph",
     test_cases.graphs,
 )
 def test_prepare_graph_vertexes(graph):
-    vertexes, _ = prepare_graph(graph)
+    vertexes = prepare_graph(graph)
 
     # same length
     assert len(vertexes) == len(graph.nodes)
 
-    # same rank
-    assert all(
-        map(
-            lambda idx: vertexes[idx].rank == graph.nodes[idx]["rank"],
-            range(len(vertexes)),
-        )
-    )
-
     # counterimage
     my_counterimage = [
         map(attrgetter("label"), vertex.counterimage) for vertex in vertexes
@@ -101,7 +82,8 @@ def test_prepare_graph_vertexes(graph):
 
 @pytest.mark.parametrize("graph", test_cases.graphs)
 def test_create_initial_partition(graph):
-    vertexes, max_rank = prepare_graph(graph)
+    vertexes = prepare_graph(graph)
+    max_rank = max(vertex.rank for vertex in vertexes)
     partition = create_initial_partition(vertexes, max_rank)
 
     # at most one block per rank
@@ -122,7 +104,8 @@ def test_create_initial_partition(graph):
 
 @pytest.mark.parametrize("graph", test_cases.graphs)
 def test_split_upper_ranks(graph):
-    vertexes, max_rank = prepare_graph(graph)
+    vertexes = prepare_graph(graph)
+    max_rank = max(vertex.rank for vertex in vertexes)
     partition_length = 0 if max_rank == float("-inf") else max_rank + 2
 
     for idx in range(partition_length):
diff --git a/tests/fba/test_fba_rscp_utilities.py b/tests/fba/test_fba_rscp_utilities.py
index f548c98..57095fd 100644
--- a/tests/fba/test_fba_rscp_utilities.py
+++ b/tests/fba/test_fba_rscp_utilities.py
@@ -15,7 +15,7 @@ def build_test_blocks(graph, partition, expected):
     # this is needed to avoid an error
     for node in graph.nodes:
         graph.nodes[node]["rank"] = 0
-    (vertexes, _) = to_normal_graph(graph)
+    vertexes = to_normal_graph(graph)
     return (
         _Block([vertexes[idx] for idx in partition[0]], None),
         _Block([vertexes[idx] for idx in partition[1]], None),