Support deprecated message and fields (#126)

tests/test_deprecated.py

@@ -0,0 +1,26 @@
+import pytest
+
+from tests.output_betterproto.deprecated import Test as DeprecatedMessageTest
+from tests.output_betterproto.deprecated_field import Test as DeprecatedFieldTest
+
+
+def test_deprecated_message():
+    with pytest.deprecated_call():
+        DeprecatedMessageTest(value=10)
+
+
+def test_deprecated_message_with_deprecated_field():
+    with pytest.warns(None) as record:
+        DeprecatedMessageTest(v=10, value=10)
+    assert len(record) == 2
+
+
+def test_deprecated_field_warning():
+    with pytest.deprecated_call():
+        DeprecatedFieldTest(v=10, value=10)
+
+
+def test_deprecated_field_no_warning():
+    with pytest.warns(None) as record:
+        DeprecatedFieldTest(value=10)
+    assert not record