ci: adapt tests to igraph 1.0 (#3868)

Author: flying-sheep

tests/_images/paga/expected.png

@@ -67,7 +67,7 @@ def test_leiden_random_state(adata_neighbors, flavor):
     adata_2 = sc.tl.leiden(
         adata_neighbors,
         flavor=flavor,
-        random_state=2,
+        random_state=3,
         copy=True,
         directed=is_leiden_alg,
         n_iterations=n_iterations,

tests/_images/paga_continuous/expected.png

@@ -1,19 +1,27 @@
 from __future__ import annotations
 
 from functools import partial
+from importlib.util import find_spec
 from pathlib import Path
 
 import numpy as np
 import pytest
 from matplotlib import cm
+from packaging.version import Version
 
 import scanpy as sc
+from scanpy._compat import pkg_version
 from testing.scanpy._helpers.data import pbmc3k_processed, pbmc68k_reduced
 from testing.scanpy._pytest.marks import needs
 
 HERE: Path = Path(__file__).parent
 ROOT = HERE / "_images"
 
+SKIP_IF_OLD_IGRAPH = pytest.mark.skipif(
+    not find_spec("igraph") or pkg_version("igraph") < Version("1"),
+    reason="igraph 0.x has different RNG behavior",
+)
+
 
 pytestmark = [needs.igraph]
 
@@ -32,6 +40,7 @@ def pbmc(pbmc_session):
     return pbmc_session.copy()
 
 
+@SKIP_IF_OLD_IGRAPH
 @pytest.mark.parametrize(
     ("test_id", "func"),
     [
@@ -60,14 +69,15 @@ def test_paga_plots(image_comparer, pbmc, test_id, func):
     save_and_compare_images(f"paga_{test_id}" if test_id else "paga")
 
 
+@SKIP_IF_OLD_IGRAPH
 def test_paga_pie(image_comparer, pbmc) -> None:
     save_and_compare_images = partial(image_comparer, ROOT, tol=30)
 
     colors = {
-        c: {cm.Set1(_): 0.33 for _ in range(3)}
+        c: {cm.Set1(i): 0.33 for i in range(3)}
         for c in pbmc.obs["bulk_labels"].cat.categories
     }
-    colors["Dendritic"] = {cm.Set2(_): 0.25 for _ in range(4)}
+    colors["Dendritic"] = {cm.Set2(i): 0.25 for i in range(4)}
 
     sc.pl.paga(pbmc, color=colors, colorbar=False, show=False)
     save_and_compare_images("paga_pie")