Merge pull request #7748 from jkseppan/deterministic-tests

QuLogic · web-flow · commit b6f13f188618 · 2017-01-21T18:45:55.000-05:00
MAINT: Deterministic SVG and PDF tests
diff --git a/doc/users/whats_new/reproducible_ps_pdf.rst b/doc/users/whats_new/reproducible_ps_pdf.rst
@@ -1,14 +1,28 @@
-Reproducible PS and PDF output
-------------------------------
+Reproducible PS, PDF and SVG output
+-----------------------------------
 
 The ``SOURCE_DATE_EPOCH`` environment variable can now be used to set
 the timestamp value in the PS and PDF outputs. See
 https://reproducible-builds.org/specs/source-date-epoch/
 
+Alternatively, calling ``savefig`` with ``metadata={'creationDate': None}``
+will omit the timestamp altogether.
+
 The reproducibility of the output from the PS and PDF backends has so
 far been tested using various plot elements but only default values of
 options such as ``{ps,pdf}.fonttype`` that can affect the output at a
 low level, and not with the mathtext or usetex features. When
 matplotlib calls external tools (such as PS distillers or LaTeX) their
 versions need to be kept constant for reproducibility, and they may
 add sources of nondeterminism outside the control of matplotlib.
+
+For SVG output, the ``svg.hashsalt`` rc parameter has been added in an
+earlier release. This parameter changes some random identifiers in the
+SVG file to be deterministic. The downside of this setting is that if
+more than one file is generated using deterministic identifiers
+and they end up as parts of one larger document, the identifiers can
+collide and cause the different parts to affect each other.
+
+These features are now enabled in the tests for the PDF and SVG
+backends, so most test output files (but not all of them) are now
+deterministic.
diff --git a/lib/matplotlib/backends/backend_pdf.py b/lib/matplotlib/backends/backend_pdf.py
@@ -472,7 +472,6 @@ def __init__(self, filename, metadata=None):
                 'Pages': self.pagesObject}
         self.writeObject(self.rootObject, root)
 
-        revision = ''
         # get source date from SOURCE_DATE_EPOCH, if set
         # See https://reproducible-builds.org/specs/source-date-epoch/
         source_date_epoch = os.getenv("SOURCE_DATE_EPOCH")
@@ -484,11 +483,13 @@ def __init__(self, filename, metadata=None):
 
         self.infoDict = {
             'Creator': 'matplotlib %s, http://matplotlib.org' % __version__,
-            'Producer': 'matplotlib pdf backend%s' % revision,
+            'Producer': 'matplotlib pdf backend %s' % __version__,
             'CreationDate': source_date
         }
         if metadata is not None:
             self.infoDict.update(metadata)
+        self.infoDict = {k: v for (k, v) in self.infoDict.items()
+                         if v is not None}
 
         self.fontNames = {}     # maps filenames to internal font names
         self.nextFont = 1       # next free internal font name
@@ -2459,6 +2460,13 @@ def __init__(self, filename, keep_empty=True, metadata=None):
             'Document Information Dictionary'), e.g.:
             `{'Creator': 'My software', 'Author': 'Me',
             'Title': 'Awesome fig'}`
+
+            The standard keys are `'Title'`, `'Author'`, `'Subject'`,
+            `'Keywords'`, `'Creator'`, `'Producer'`, `'CreationDate'`,
+            `'ModDate'`, and `'Trapped'`. Values have been predefined
+            for `'Creator'`, `'Producer'` and `'CreationDate'`. They
+            can be removed by setting them to `None`.
+
         """
         self._file = PdfFile(filename, metadata=metadata)
         self.keep_empty = keep_empty
diff --git a/lib/matplotlib/testing/__init__.py b/lib/matplotlib/testing/__init__.py
@@ -136,6 +136,10 @@ def set_font_settings_for_testing():
     rcParams['text.hinting_factor'] = 8
 
 
+def set_reproducibility_for_testing():
+    rcParams['svg.hashsalt'] = 'matplotlib'
+
+
 def setup():
     # The baseline images are created in this locale, so we should use
     # it during all of the tests.
@@ -161,3 +165,4 @@ def setup():
     rcdefaults()  # Start with all defaults
 
     set_font_settings_for_testing()
+    set_reproducibility_for_testing()
diff --git a/lib/matplotlib/testing/decorators.py b/lib/matplotlib/testing/decorators.py
@@ -298,7 +298,12 @@ def compare(self, idx, baseline, extension):
             remove_ticks_and_titles(fig)
 
         actual_fname = os.path.join(self.result_dir, baseline) + '.' + extension
-        fig.savefig(actual_fname, **self.savefig_kwargs)
+        kwargs = self.savefig_kwargs.copy()
+        if extension == 'pdf':
+            kwargs.setdefault('metadata',
+                              {'Creator': None, 'Producer': None,
+                               'CreationDate': None})
+        fig.savefig(actual_fname, **kwargs)
 
         expected_fname = self.copy_baseline(baseline, extension)
         raise_on_image_difference(expected_fname, actual_fname, self.tol)
