Save images from image tests

.gitignore

@@ -75,4 +75,6 @@ $RECYCLE.BIN/
 .hypothesis/
 .pytest_cache/
 sunpydata.sqlite
+
 v/
+result_images*

sunpy/conftest.py

@@ -14,7 +14,7 @@
     matplotlib.use('Agg')
 
 from sunpy.tests.hash import HASH_LIBRARY_NAME
-from sunpy.tests.helpers import new_hash_library, figure_test_pngfiles
+from sunpy.tests.helpers import new_hash_library, test_fig_dir
 from sunpy.extern import six
 
 import pytest
@@ -47,17 +47,11 @@ def pytest_runtest_setup(item):
 
 
 def pytest_unconfigure(config):
-    if len(figure_test_pngfiles) > 0:
-        tempdir = tempfile.mkdtemp(suffix="_figures")
-
-        # Rename each PNG with the name of the corresponding test
-        for test_name in figure_test_pngfiles:
-            os.rename(figure_test_pngfiles[test_name], os.path.join(tempdir, test_name + '.png'))
-
+    if len(new_hash_library) > 0:
         # Write the new hash library in JSON
-        hashfile = os.path.join(tempdir, HASH_LIBRARY_NAME)
+        hashfile = os.path.join(test_fig_dir, HASH_LIBRARY_NAME)
         with open(hashfile, 'w') as outfile:
             json.dump(new_hash_library, outfile, sort_keys=True, indent=4, separators=(',', ': '))
 
-        print('All test files for figure hashes can be found in {0}'.format(tempdir))
+        print('All images from image tests can be found in {0}'.format(test_fig_dir))
         print("The corresponding hash library is {0}".format(hashfile))

sunpy/tests/hash.py

@@ -46,11 +46,18 @@ def hash_figure(figure=None, out_stream=None):
 
     figure.savefig(imgdata, format='png')
 
-    imgdata.seek(0)
-    buf = imgdata.read()
+    out = _hash_file(imgdata)
     if out_stream is None:
         imgdata.close()
+    return out
 
+
+def _hash_file(in_stream):
+    """
+    Hashes an already opened file
+    """
+    in_stream.seek(0)
+    buf = in_stream.read()
     hasher = hashlib.sha256()
     hasher.update(buf)
     return hasher.hexdigest()

sunpy/tests/helpers.py

@@ -7,6 +7,7 @@
 import tempfile
 import platform
 import os
+import datetime
 
 import pytest
 import numpy as np
@@ -40,9 +41,7 @@
     SKIP_ANA = False
 
 skip_windows = pytest.mark.skipif(platform.system() == 'Windows', reason="Windows")
-
 skip_glymur = pytest.mark.skipif(SKIP_GLYMUR, reason="Glymur can not be imported")
-
 skip_ana = pytest.mark.skipif(SKIP_ANA, reason="ANA is not available")
 
 
@@ -52,19 +51,21 @@ def warnings_as_errors(request):
 
     request.addfinalizer(lambda *args: warnings.resetwarnings())
 
-new_hash_library = {}
 
-figure_test_pngfiles = {}
+hash_library = hash.hash_library
+new_hash_library = {}
+test_fig_dir = 'result_images_{:%H%M%S}'.format(datetime.datetime.now())
 
 
 def figure_test(test_function):
     """
     A decorator for a test that verifies the hash of the current figure or the returned figure,
     with the name of the test function as the hash identifier in the library.
-    A PNG is also created with a temporary filename, with the lookup stored in the
-    `figure_test_pngfiles` dictionary.
+    A PNG is also created in the 'result_image' directory, which is created
+    on the current path.
 
-    All such decorated tests are marked with `pytest.mark.figure` for convenient filtering.
+    All such decorated tests are marked with `pytest.mark.figure` for
+    convenient filtering.
 
     Examples
     --------
@@ -77,16 +78,33 @@ def test_simple_plot():
     def wrapper(*args, **kwargs):
         if not os.path.exists(hash.HASH_LIBRARY_FILE):
             pytest.xfail('Could not find a figure hash library at {}'.format(hash.HASH_LIBRARY_FILE))
+
+        name = "{0}.{1}".format(test_function.__module__,
+                                test_function.__name__)
+        # Run the test function and get the figure
         plt.figure()
-        name = "{0}.{1}".format(test_function.__module__, test_function.__name__)
-        pngfile = tempfile.NamedTemporaryFile(delete=False)
-        figure_hash = hash.hash_figure(test_function(*args, **kwargs), out_stream=pngfile)
-        figure_test_pngfiles[name] = pngfile.name
-        pngfile.close()
+        fig = test_function(*args, **kwargs)
+        if fig is None:
+            fig = plt.gcf()
+
+        # Save the image that was generated
+        if not os.path.exists(test_fig_dir):
+            os.mkdir(test_fig_dir)
+        result_image_loc = os.path.join(test_fig_dir, '{}.png'.format(name))
+        plt.savefig(result_image_loc)
+        plt.close()
+
+        # Create hash
+        imgdata = open(result_image_loc, "rb")
+        figure_hash = hash._hash_file(imgdata)
+        imgdata.close()
+
         new_hash_library[name] = figure_hash
-        if name not in hash.hash_library:
+        if name not in hash_library:
             pytest.fail("Hash not present: {0}".format(name))
-        else:
-            assert hash.hash_library[name] == figure_hash
-        plt.close()
+
+        if hash_library[name] != figure_hash:
+            raise RuntimeError('Figure hash does not match expected hash.\n'
+                               'New image generated and placed at {}'.format(result_image_loc))
+
     return wrapper