Adding new Sync strategy

Updated test case

Updated doc comment

Added test cases

Author: Rakshil Modi

awscli/customizations/s3/syncstrategy/nooverwrite.py

@@ -0,0 +1,45 @@
+# Copyright 2014 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"). You
+# may not use this file except in compliance with the License. A copy of
+# the License is located at
+#
+# http://aws.amazon.com/apache2.0/
+#
+# or in the "license" file accompanying this file. This file is
+# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
+# ANY KIND, either express or implied. See the License for the specific
+# language governing permissions and limitations under the License.
+import logging
+
+from awscli.customizations.s3.subcommands import NO_OVERWRITE
+from awscli.customizations.s3.syncstrategy.base import BaseSync
+
+LOG = logging.getLogger(__name__)
+
+
+class NoOverwriteSync(BaseSync):
+    """Sync strategy that prevents overwriting of existing files at the destination.
+    This strategy will only sync files that don't exist at the destination.
+    If a file exists at both source and destination, it will be skipped regardless
+    of size or modification time differences.
+    """
+
+    ARGUMENT = NO_OVERWRITE
+
+    def determine_should_sync(self, src_file, dest_file):
+        if not dest_file:
+            # Sync if file does not exist at destination
+            return True
+        elif src_file.compare_key != dest_file.compare_key:
+            # Sync if file exists at both source and destination but the
+            # source file's key is different than the destination file's key
+            return True
+        else:
+            # Skip if file exists at both source and destination
+            LOG.debug(
+                "Warning: Skipping file %s as it already exists on %s",
+                src_file.src,
+                src_file.dest,
+            )
+            return False

awscli/customizations/s3/syncstrategy/register.py

@@ -14,6 +14,7 @@
 from awscli.customizations.s3.syncstrategy.exacttimestamps import (
     ExactTimestampsSync,
 )
+from awscli.customizations.s3.syncstrategy.nooverwrite import NoOverwriteSync
 from awscli.customizations.s3.syncstrategy.sizeonly import SizeOnlySync
 
 
@@ -48,4 +49,7 @@ def register_sync_strategies(command_table, session, **kwargs):
     # Register the delete sync strategy.
     register_sync_strategy(session, DeleteSync, 'file_not_at_src')
 
+    # Register the noOverwrite sync strategy
+    register_sync_strategy(session, NoOverwriteSync, 'file_at_src_and_dest')
+
     # Register additional sync strategies here...

tests/unit/customizations/s3/syncstrategy/test_nooverwrite.py

@@ -0,0 +1,110 @@
+# Copyright 2014 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"). You
+# may not use this file except in compliance with the License. A copy of
+# the License is located at
+#
+# http://aws.amazon.com/apache2.0/
+#
+# or in the "license" file accompanying this file. This file is
+# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
+# ANY KIND, either express or implied. See the License for the specific
+# language governing permissions and limitations under the License.
+import datetime
+
+from awscli.customizations.s3.filegenerator import FileStat
+from awscli.customizations.s3.syncstrategy.nooverwrite import NoOverwriteSync
+from awscli.testutils import unittest
+
+
+class TestNoOverwriteSync(unittest.TestCase):
+    def setUp(self):
+        self.sync_strategy = NoOverwriteSync()
+
+    def test_file_does_not_exist_at_destination(self):
+        """
+        Confirms that files are synced when not present at destination.
+        """
+        time_src = datetime.datetime.now()
+
+        src_file = FileStat(
+            src='',
+            dest='',
+            compare_key='test.py',
+            size=10,
+            last_update=time_src,
+            src_type='s3',
+            dest_type='local',
+            operation_name='download',
+        )
+        dest_file = None
+        should_sync = self.sync_strategy.determine_should_sync(
+            src_file, dest_file
+        )
+        self.assertTrue(should_sync)
+
+    def test_file_exists_at_destination_with_different_key(self):
+        """
+        Confirms that files are synced when key differs.
+        """
+        time_src = datetime.datetime.now()
+
+        src_file = FileStat(
+            src='',
+            dest='',
+            compare_key='test.py',
+            size=10,
+            last_update=time_src,
+            src_type='s3',
+            dest_type='s3',
+            operation_name='copy',
+        )
+        dest_file = FileStat(
+            src='',
+            dest='',
+            compare_key='test1.py',
+            size=100,
+            last_update=time_src,
+            src_type='s3',
+            dest_type='s3',
+            operation_name='',
+        )
+        should_sync = self.sync_strategy.determine_should_sync(
+            src_file, dest_file
+        )
+        self.assertTrue(should_sync)
+
+    def test_file_exists_at_destination_with_same_key(self):
+        """
+        Confirm that files with the same key are not synced.
+        """
+        time_src = datetime.datetime.now()
+
+        src_file = FileStat(
+            src='',
+            dest='',
+            compare_key='test.py',
+            size=10,
+            last_update=time_src,
+            src_type='local',
+            dest_type='s3',
+            operation_name='upload',
+        )
+        dest_file = FileStat(
+            src='',
+            dest='',
+            compare_key='test.py',
+            size=100,
+            last_update=time_src,
+            src_type='local',
+            dest_type='s3',
+            operation_name='',
+        )
+        should_sync = self.sync_strategy.determine_should_sync(
+            src_file, dest_file
+        )
+        self.assertFalse(should_sync)
+
+
+if __name__ == "__main__":
+    unittest.main()