TST: only partially skip image tests when pytest-mpl is missing

Author: neutrinoceros

tests/conftest.py

@@ -16,17 +16,10 @@ def pytest_configure(config):
         mpl.use("Agg")
     else:  # pragma: no cover
         config.addinivalue_line(
-            "markers", "mpl_image_compare: skip (missing requirement: pytest_mpl)"
+            "markers", "mpl_image_compare: partial skip (missing requirement: pytest_mpl)"
         )
 
 
-def pytest_runtest_setup(item):
-    if HAVE_PYTEST_MPL:
-        return
-    if any(item.iter_markers(name="mpl_image_compare")):  # pragma: no cover
-        pytest.skip("missing requirement: pytest_mpl")
-
-
 def pytest_report_header(config, start_path) -> list[str]:
     fs = runtime_feature_set()
     diagnostics = fs.diagnostics(features=["free-threading", "JIT"])

tests/test_deposit.py

@@ -11,6 +11,8 @@
 import gpgi
 from gpgi._lib import _deposit_ngp_2D
 
+from importlib.util import find_spec
+HAVE_PYTEST_MPL = find_spec("pytest-mpl") is not None
 
 @pytest.fixture()
 def sample_2D_dataset():
@@ -120,11 +122,12 @@ def fake_dep(*args, metadata=None, **kwargs):
 @pytest.mark.parametrize("method", ["ngp", "cic", "tsc"])
 @pytest.mark.mpl_image_compare
 def test_2D_deposit(sample_2D_dataset, method):
-    from matplotlib.figure import Figure
 
     ds = sample_2D_dataset
     particle_density = ds.deposit("mass", method=method)
 
+    if not HAVE_PYTEST_MPL: return
+    from matplotlib.figure import Figure
     fig = Figure()
     ax = fig.add_subplot()
 
@@ -178,6 +181,7 @@ def test_1D_deposit(method, grid_type):
     if method == "ngp":
         assert mass.sum() == ds.particles.count
 
+    if not HAVE_PYTEST_MPL: return
     fig = Figure()
     ax = fig.add_subplot()
     ax.set(xlabel="x", ylabel="particle mass", title=f"Deposition method '{method}'")
@@ -241,10 +245,9 @@ def test_3D_deposit(method, dtype):
     assert deposit_3D.shape == tuple(a - 2 for a in full_deposit_3D.shape)
 
 
+
 @pytest.mark.mpl_image_compare
 def test_readme_example():
-    from matplotlib.figure import Figure
-
     nx = ny = 64
     nparticles = 600_000
 
@@ -271,6 +274,10 @@ def test_readme_example():
 
     particle_mass = ds.deposit("mass", method="nearest_grid_point")
 
+    if not HAVE_PYTEST_MPL: return
+    from matplotlib.figure import Figure
+
+
     fig = Figure()
     ax = fig.add_subplot()
     ax.set(aspect=1, xlabel="x", ylabel="y")