Add warnings about deprecated modules (#4527)

moto/__init__.py

@@ -1,8 +1,17 @@
 import importlib
 
 
-def lazy_load(module_name, element, boto3_name=None, backend=None):
+def lazy_load(
+    module_name, element, boto3_name=None, backend=None, warn_repurpose=False
+):
     def f(*args, **kwargs):
+        if warn_repurpose:
+            import warnings
+
+            warnings.warn(
+                f"Module {element} has been deprecated, and will be repurposed in a later release. "
+                "Please see https://github.com/spulec/moto/issues/4526 for more information."
+            )
         module = importlib.import_module(module_name, "moto")
         return getattr(module, element)(*args, **kwargs)
 
@@ -53,7 +62,7 @@ mock_datapipeline_deprecated = lazy_load(
 mock_datasync = lazy_load(".datasync", "mock_datasync")
 mock_dms = lazy_load(".dms", "mock_dms")
 mock_ds = lazy_load(".ds", "mock_ds", boto3_name="ds")
-mock_dynamodb = lazy_load(".dynamodb", "mock_dynamodb")
+mock_dynamodb = lazy_load(".dynamodb", "mock_dynamodb", warn_repurpose=True)
 mock_dynamodb_deprecated = lazy_load(".dynamodb", "mock_dynamodb_deprecated")
 mock_dynamodb2 = lazy_load(".dynamodb2", "mock_dynamodb2", backend="dynamodb_backends2")
 mock_dynamodb2_deprecated = lazy_load(".dynamodb2", "mock_dynamodb2_deprecated")
@@ -99,7 +108,7 @@ mock_opsworks_deprecated = lazy_load(".opsworks", "mock_opsworks_deprecated")
 mock_organizations = lazy_load(".organizations", "mock_organizations")
 mock_polly = lazy_load(".polly", "mock_polly")
 mock_ram = lazy_load(".ram", "mock_ram")
-mock_rds = lazy_load(".rds", "mock_rds")
+mock_rds = lazy_load(".rds", "mock_rds", warn_repurpose=True)
 mock_rds_deprecated = lazy_load(".rds", "mock_rds_deprecated")
 mock_rds2 = lazy_load(".rds2", "mock_rds2", boto3_name="rds")
 mock_rds2_deprecated = lazy_load(".rds2", "mock_rds2_deprecated")

tests/test_dynamodb/test_dynamodb.py

@@ -3,12 +3,20 @@ import boto.dynamodb
 import sure  # noqa # pylint: disable=unused-import
 import pytest
 
-from moto import mock_dynamodb_deprecated
+from moto import mock_dynamodb, mock_dynamodb_deprecated
 from moto.dynamodb import dynamodb_backend
 
 from boto.exception import DynamoDBResponseError
 
 
+def test_deprecation_warning():
+    with pytest.warns(None) as record:
+        mock_dynamodb()
+    str(record[0].message).should.contain(
+        "Module mock_dynamodb has been deprecated, and will be repurposed in a later release"
+    )
+
+
 # Has boto3 equivalent
 @mock_dynamodb_deprecated
 def test_list_tables():

tests/test_rds/test_rds.py

@@ -3,10 +3,19 @@ import boto.rds
 import boto.vpc
 from boto.exception import BotoServerError
 import sure  # noqa # pylint: disable=unused-import
+import pytest
 
 from moto import mock_ec2_deprecated, mock_rds_deprecated, mock_rds
 
 
+def test_deprecation_warning():
+    with pytest.warns(None) as record:
+        mock_rds()
+    str(record[0].message).should.contain(
+        "Module mock_rds has been deprecated, and will be repurposed in a later release"
+    )
+
+
 @mock_rds_deprecated
 def test_create_database():
     conn = boto.rds.connect_to_region("us-west-2")