Add warnings when calling deprecated method

src/betterproto/plugin/models.py

@@ -275,8 +275,21 @@ def input_filenames(self) -> Iterable[str]:
     @property
     def python_module_imports(self) -> Set[str]:
         imports = set()
+
+        has_deprecated = False
+        if any(m.deprecated for m in self.messages):
+            has_deprecated = True
         if any(x for x in self.messages if any(x.deprecated_fields)):
+            has_deprecated = True
+        if any(
+            any(m.proto_obj.options.deprecated for m in s.methods)
+            for s in self.services
+        ):
+            has_deprecated = True
+
+        if has_deprecated:
             imports.add("warnings")
+
         if self.builtins_import:
             imports.add("builtins")
         return imports

src/betterproto/templates/template.py.j2

@@ -84,6 +84,10 @@ class {{ service.py_name }}Stub(betterproto.ServiceStub):
         {% if method.comment %}
 {{ method.comment }}
 
+        {% endif %}
+        {% if method.proto_obj.options.deprecated %}
+        warnings.warn("{{ service.py_name }}.{{ method.py_name }} is deprecated", DeprecationWarning)
+
         {% endif %}
         {% if method.server_streaming %}
             {% if method.client_streaming %}

tests/inputs/deprecated/deprecated.proto

@@ -12,3 +12,10 @@ message Message {
     option deprecated = true;
     string value = 1;
 }
+
+message Empty {}
+
+service TestService {
+    rpc func(Empty) returns (Empty);
+    rpc deprecated_func(Empty) returns (Empty) { option deprecated = true; };
+}

tests/test_deprecated.py

@@ -2,9 +2,12 @@
 
 import pytest
 
+from tests.mocks import MockChannel
 from tests.output_betterproto.deprecated import (
+    Empty,
     Message,
     Test,
+    TestServiceStub,
 )
 
 
@@ -43,3 +46,19 @@ def test_message_with_deprecated_field_not_set_default(message):
         _ = Test(value=10).message
 
     assert not record
+
+
+@pytest.mark.asyncio
+async def test_service_with_deprecated_method():
+    stub = TestServiceStub(MockChannel([Empty(), Empty()]))
+
+    with pytest.warns(DeprecationWarning) as record:
+        await stub.deprecated_func(Empty())
+
+    assert len(record) == 1
+    assert str(record[0].message) == f"TestService.deprecated_func is deprecated"
+
+    with pytest.warns(None) as record:
+        await stub.func(Empty())
+
+    assert not record