Add ignore fields parameter

README.md

@@ -35,6 +35,10 @@ class APITestCase(TestCase):
         # Set custom snapshot name: `gpg_response`
         my_gpg_response = api.client.get('/me?gpg_key')
         self.assertMatchSnapshot(my_gpg_response, 'gpg_response')
+
+        # Set ignore fields (e.g. 'created_at' : '12-12-2017')
+        ignore_date_response = {'created_at' : '01-01-2018', 'url': '/me'}
+        self.assertMatchSnapshot(ignore_date_response, ignore_fields=['created_at'])
 ```
 
 If you want to update the snapshots automatically you can use the `nosetests --snapshot-update`.
@@ -52,6 +56,10 @@ def test_mything(snapshot):
     # Set custom snapshot name: `gpg_response`
     my_gpg_response = api.client.get('/me?gpg_key')
     snapshot.assert_match(my_gpg_response, 'gpg_response')
+
+    # Set ignore fields (e.g. 'created_at' : '12-12-2017')
+    ignore_date_response = {'created_at' : '01-01-2018', 'url': '/me'}
+    snapshot.assert_match(ignore_date_response, ignore_fields=['created_at'])
 ```
 
 If you want to update the snapshots automatically you can use the `--snapshot-update` config.

README.rst

@@ -41,6 +41,10 @@ Usage with unittest/nose
             my_gpg_response = api.client.get('/me?gpg_key')
             self.assertMatchSnapshot(my_gpg_response, 'gpg_response')
 
+            # Set ignore fields (e.g. 'created_at' : '12-12-2017')
+            ignore_date_response = {'created_at' : '01-01-2018', 'url': '/me'}
+            self.assertMatchSnapshot(ignore_date_response, ignore_fields=['created_at'])
+
 If you want to update the snapshots automatically you can use the
 ``nosetests --snapshot-update``.
 
@@ -61,6 +65,10 @@ Usage with pytest
         my_gpg_response = api.client.get('/me?gpg_key')
         snapshot.assert_match(my_gpg_response, 'gpg_response')
 
+        # Set ignore fields (e.g. 'created_at' : '12-12-2017')
+        ignore_date_response = {'created_at' : '01-01-2018', 'url': '/me'}
+        snapshot.assert_match(ignore_date_response, ignore_fields=['created_at'])
+
 If you want to update the snapshots automatically you can use the
 ``--snapshot-update`` config.
 

snapshottest/module.py

@@ -231,7 +231,8 @@ def assert_value_matches_snapshot(self, test_value, snapshot_value):
     def assert_equals(self, value, snapshot):
         assert value == snapshot
 
-    def assert_match(self, value, name=''):
+    def assert_match(self, value, name='', ignore_fields=None):
+        self.remove_fields(value, ignore_fields)
         self.curr_snapshot = name or self.snapshot_counter
         self.visit()
         if self.update:
@@ -243,6 +244,7 @@ def assert_match(self, value, name=''):
                 self.store(value)  # first time this test has been seen
             else:
                 try:
+                    self.remove_fields(prev_snapshot, ignore_fields)
                     self.assert_value_matches_snapshot(value, prev_snapshot)
                 except AssertionError:
                     self.fail()
@@ -254,9 +256,21 @@ def assert_match(self, value, name=''):
     def save_changes(self):
         self.module.save()
 
-
-def assert_match_snapshot(value, name=''):
+    @classmethod
+    def remove_fields(cls, input, remove_fields_list=None):
+        if remove_fields_list is None:
+            remove_fields_list = []
+        gen = (field for field in remove_fields_list if field in input)
+        for field in gen:
+            del input[field]
+        if isinstance(input, dict):
+            gen = (value for value in input.values() if isinstance(value, dict))
+            for value in gen:
+                cls.remove_fields(value, remove_fields_list)
+
+
+def assert_match_snapshot(value, name='', ignore_fields=None):
     if not SnapshotTest._current_tester:
         raise Exception("You need to use assert_match_snapshot in the SnapshotTest context.")
 
-    SnapshotTest._current_tester.assert_match(value, name)
+    SnapshotTest._current_tester.assert_match(value, name, ignore_fields)

snapshottest/unittest.py

@@ -101,7 +101,7 @@ def tearDown(self):
         SnapshotTest._current_tester = None
         self._snapshot = None
 
-    def assert_match_snapshot(self, value, name=''):
-        self._snapshot.assert_match(value, name=name)
+    def assert_match_snapshot(self, value, name='', ignore_fields=None):
+        self._snapshot.assert_match(value, name, ignore_fields)
 
     assertMatchSnapshot = assert_match_snapshot

tests/test_pytest.py

@@ -46,3 +46,20 @@ def test_pytest_snapshottest_property_test_name(pytest_snapshot_test):
         pytest_snapshot_test.assert_match('counter')
         assert pytest_snapshot_test.test_name == \
             'test_pytest_snapshottest_property_test_name 2'
+
+
+def test_pytest_snapshottest_ignore_fields(pytest_snapshot_test):
+    ignore_fields_test = {
+        'url': 'example',
+        'date': '12-12-2017',
+        'test': {
+            'date': '11-12-2017'
+        }
+    }
+
+    pytest_snapshot_test.assert_match(
+        ignore_fields_test, 'ignore_fields_test', ignore_fields=['date']
+    )
+    ignore_fields_test.pop('date', None)
+    ignore_fields_test['test'].pop('date', None)
+    assert pytest_snapshot_test.module[pytest_snapshot_test.test_name] == ignore_fields_test