Updated PNG hashes and only set metdata for PNG output

Author: astrofrog

tests/baseline/hashes/mpl21_ft261.json

@@ -15,5 +15,5 @@
   "test.test_unmodified": "14d326881467bc613e6504b87bd7d556a5e58668ff16b896fa3c15745cfb6336",
   "test_formats.test_format_eps": "da67357559501ff4afae72acede897d75d968ba0c4573dcd7ff992cfa72e49d4",
   "test_formats.test_format_pdf": "9098ce368ec6e20951e9305fcb7da05a3f10169d270c84d8da3331371c6596bc",
-  "test_formats.test_format_png": "17b65dd0247b0dfd8c1b4b079352414ae0fe03c0a3e79d63c8b8670d84d4098f"
+  "test_formats.test_format_png": "d577a3c8c7550413d8d50bc26a68f3e8d9c35d4763c52cbcc15df4f61c8406b2"
 }

tests/baseline/hashes/mpl22_ft261.json

@@ -15,5 +15,5 @@
   "test.test_unmodified": "80e0ee6df7cf7d9d9407395a25af30beb8763e98820a7be972764899246d2cd7",
   "test_formats.test_format_eps": "da67357559501ff4afae72acede897d75d968ba0c4573dcd7ff992cfa72e49d4",
   "test_formats.test_format_pdf": "9098ce368ec6e20951e9305fcb7da05a3f10169d270c84d8da3331371c6596bc",
-  "test_formats.test_format_png": "e80557c8784fb920fb79b03b26dc072649a98811f00a8c212df8761e4351acde"
+  "test_formats.test_format_png": "d577a3c8c7550413d8d50bc26a68f3e8d9c35d4763c52cbcc15df4f61c8406b2"
 }

tests/baseline/hashes/mpl30_ft261.json

@@ -15,5 +15,5 @@
   "test.test_unmodified": "6e2e4ba7b77caf62df24f6b92d6fc51ab1b837bf98039750334f65c0a6c5d898",
   "test_formats.test_format_eps": "8ad5b5795b65e16790d1b57889540597fe18f164ddc38f50086f29e725b5c223",
   "test_formats.test_format_pdf": "18858c67f1362e6d53975b66ffc221bda0c9f714185851fbf714bd73f0a80729",
-  "test_formats.test_format_png": "4e1157a93733cdb327f1741afdb0525f4d0e3f12e60b54f72c93db9f9c9ae27f"
+  "test_formats.test_format_png": "d577a3c8c7550413d8d50bc26a68f3e8d9c35d4763c52cbcc15df4f61c8406b2"
 }

tests/baseline/hashes/mpl31_ft261.json

@@ -15,5 +15,5 @@
   "test.test_unmodified": "3675e5a48388e8cc341580e9b41115d3cf63d2465cf11eeed3faa23e84030fc2",
   "test_formats.test_format_eps": "8ad5b5795b65e16790d1b57889540597fe18f164ddc38f50086f29e725b5c223",
   "test_formats.test_format_pdf": "18858c67f1362e6d53975b66ffc221bda0c9f714185851fbf714bd73f0a80729",
-  "test_formats.test_format_png": "2a4da3a36b384df539f3f47d476f67a918f5eee1df360dbab9469b96260df78f"
+  "test_formats.test_format_png": "d577a3c8c7550413d8d50bc26a68f3e8d9c35d4763c52cbcc15df4f61c8406b2"
 }

tests/baseline/hashes/mpl32_ft261.json

@@ -15,5 +15,5 @@
   "test.test_unmodified": "3b7db65812fd59403d17a2fba3ebe1fd0abdfde8633df06636e4e1daea259da0",
   "test_formats.test_format_eps": "8ad5b5795b65e16790d1b57889540597fe18f164ddc38f50086f29e725b5c223",
   "test_formats.test_format_pdf": "18858c67f1362e6d53975b66ffc221bda0c9f714185851fbf714bd73f0a80729",
-  "test_formats.test_format_png": "8b8ff9ce044bc9075876278781667a708414460209bba25a39d8262ed73d0f04"
+  "test_formats.test_format_png": "d577a3c8c7550413d8d50bc26a68f3e8d9c35d4763c52cbcc15df4f61c8406b2"
 }

tests/baseline/hashes/mpl33_ft261.json

@@ -15,6 +15,6 @@
   "test.test_unmodified": "ce07de6b726c3b01afb03aa7c9e939d584bc71a54b9737d69853a0d915cd6181",
   "test_formats.test_format_eps": "8ad5b5795b65e16790d1b57889540597fe18f164ddc38f50086f29e725b5c223",
   "test_formats.test_format_pdf": "18858c67f1362e6d53975b66ffc221bda0c9f714185851fbf714bd73f0a80729",
-  "test_formats.test_format_png": "55ad74a44c99606f1df1e79f67a59a4986bddc2b48ea2b2d7ea8365db91dc7ca",
+  "test_formats.test_format_png": "e73d228183ddfdced366191399cdecef9685d1248b852162f179750fc7b8b904",
   "test_formats.test_format_svg": "f21b81fdc6163a13caf7fa675d42b996ab7f0070c063a287a00d13d50c5b38f1"
 }

tests/test_pytest_mpl.py

@@ -691,6 +691,11 @@ def test_formats(pytester, use_hash_library, passes, file_format):
         else:
             pytest.skip('Comparing EPS and PDF files requires ghostscript to be installed')
 
+    if file_format == 'png':
+        metadata = '{"Software": None}'
+    else:
+        metadata = '{}'
+
     pytester.makepyfile(
         f"""
         import pytest
@@ -699,7 +704,7 @@ def test_formats(pytester, use_hash_library, passes, file_format):
                                        {f'hash_library=r"{hash_library}",' if use_hash_library else ''}
                                        tolerance={DEFAULT_TOLERANCE},
                                        savefig_kwargs={{'format': '{file_format}',
-                                                        'metadata': {{"Software": None}}}})
+                                                        'metadata': {metadata}}})
         def test_format_{file_format}():
             fig = plt.figure()
             ax = fig.add_subplot(1, 1, 1)