Rely on pytest to record warnings, rather than doing it manually.

anntzer · anntzer · commit 2ad47ca08a2f · 2019-12-29T22:33:52.000+01:00
Technically we could even get rid of the `assert len(recwarn) == 0`
lines because we fail the tests on any warning, but I left them there
for explicitness.
diff --git a/lib/matplotlib/tests/test_artist.py b/lib/matplotlib/tests/test_artist.py
@@ -1,6 +1,5 @@
 import io
 from itertools import chain
-import warnings
 
 import numpy as np
 
@@ -220,13 +219,10 @@ def test_default_edges():
     ax4.add_patch(pp1)
 
 
-def test_properties():
+def test_properties(recwarn):
     ln = mlines.Line2D([], [])
-    with warnings.catch_warnings(record=True) as w:
-        # Cause all warnings to always be triggered.
-        warnings.simplefilter("always")
-        ln.properties()
-        assert len(w) == 0
+    ln.properties()
+    assert len(recwarn) == 0
 
 
 def test_setp():
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -5283,17 +5283,13 @@ def test_length_one_hist():
     ax.hist([1])
 
 
-def test_pathological_hexbin():
+def test_pathological_hexbin(recwarn):
     # issue #2863
-    out = io.BytesIO()
-
-    with warnings.catch_warnings(record=True) as w:
-        warnings.simplefilter("always")
-        mylist = [10] * 100
-        fig, ax = plt.subplots(1, 1)
-        ax.hexbin(mylist, mylist)
-        fig.savefig(out)
-        assert len(w) == 0
+    mylist = [10] * 100
+    fig, ax = plt.subplots(1, 1)
+    ax.hexbin(mylist, mylist)
+    fig.savefig(io.BytesIO())
+    assert len(recwarn) == 0
 
 
 def test_color_None():
diff --git a/lib/matplotlib/tests/test_image.py b/lib/matplotlib/tests/test_image.py
@@ -6,7 +6,6 @@
 import platform
 import sys
 import urllib.request
-import warnings
 
 import numpy as np
 from numpy import ma
@@ -981,11 +980,9 @@ def test_imshow_masked_interpolation():
         ax.axis('off')
 
 
-def test_imshow_no_warn_invalid():
-    with warnings.catch_warnings(record=True) as warns:
-        warnings.simplefilter("always")
-        plt.imshow([[1, 2], [3, np.nan]])
-    assert len(warns) == 0
+def test_imshow_no_warn_invalid(recwarn):
+    plt.imshow([[1, 2], [3, np.nan]])
+    assert len(recwarn) == 0
 
 
 @pytest.mark.parametrize(
diff --git a/lib/matplotlib/tests/test_quiver.py b/lib/matplotlib/tests/test_quiver.py
@@ -1,4 +1,3 @@
-import warnings
 import numpy as np
 import pytest
 import sys
@@ -72,29 +71,25 @@ def test_quiver_arg_sizes():
         plt.quiver(X2, X2, X2, X2, X3)
 
 
-def test_no_warnings():
+def test_no_warnings(recwarn):
     fig, ax = plt.subplots()
-
     X, Y = np.meshgrid(np.arange(15), np.arange(10))
     U = V = np.ones_like(X)
-
     phi = (np.random.rand(15, 10) - .5) * 150
-    with warnings.catch_warnings(record=True) as w:
-        ax.quiver(X, Y, U, V, angles=phi)
-        fig.canvas.draw()
-    assert len(w) == 0
+    ax.quiver(X, Y, U, V, angles=phi)
+    fig.canvas.draw()
+    assert len(recwarn) == 0
 
 
-def test_zero_headlength():
+def test_zero_headlength(recwarn):
     # Based on report by Doug McNeil:
     # http://matplotlib.1069221.n5.nabble.com/quiver-warnings-td28107.html
     fig, ax = plt.subplots()
     X, Y = np.meshgrid(np.arange(10), np.arange(10))
     U, V = np.cos(X), np.sin(Y)
-    with warnings.catch_warnings(record=True) as w:
-        ax.quiver(U, V, headlength=0, headaxislength=0)
-        fig.canvas.draw()
-    assert len(w) == 0
+    ax.quiver(U, V, headlength=0, headaxislength=0)
+    fig.canvas.draw()
+    assert len(recwarn) == 0
 
 
 @image_comparison(['quiver_animated_test_image.png'])
