Add jpeg dpi test

dstansby · dstansby · commit d6dc2c725ea2 · 2017-08-23T08:24:39.000+01:00
diff --git a/lib/matplotlib/tests/test_agg.py b/lib/matplotlib/tests/test_agg.py
@@ -7,6 +7,7 @@
 import numpy as np
 from numpy.testing import assert_array_almost_equal
 import pytest
+from PIL import Image
 
 from matplotlib.image import imread
 from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
@@ -234,3 +235,12 @@ def test_chunksize():
     rcParams['agg.path.chunksize'] = 105
     ax.plot(x, np.sin(x))
     fig.canvas.draw()
+
+
+@pytest.mark.backend('Agg')
+def test_jpeg_dpi():
+    # Check that dpi is set correctly in jpg files
+    plt.plot([0, 1, 2], [0, 1, 0])
+    plt.savefig('test.jpg', dpi=200)
+    im = Image.open("test.jpg")
+    assert im.info['dpi'] == (200, 200)
