Generate grpclib service stubs (#170)

tests/inputs/example_service/test_example_service.py

@@ -0,0 +1,95 @@
+from typing import AsyncIterator, AsyncIterable
+
+import pytest
+from grpclib.testing import ChannelFor
+
+from tests.output_betterproto.example_service.example_service import (
+    TestBase,
+    TestStub,
+    ExampleRequest,
+    ExampleResponse,
+)
+
+
+class ExampleService(TestBase):
+    async def example_unary_unary(
+        self, example_string: str, example_integer: int
+    ) -> "ExampleResponse":
+        return ExampleResponse(
+            example_string=example_string,
+            example_integer=example_integer,
+        )
+
+    async def example_unary_stream(
+        self, example_string: str, example_integer: int
+    ) -> AsyncIterator["ExampleResponse"]:
+        response = ExampleResponse(
+            example_string=example_string,
+            example_integer=example_integer,
+        )
+        yield response
+        yield response
+        yield response
+
+    async def example_stream_unary(
+        self, request_iterator: AsyncIterator["ExampleRequest"]
+    ) -> "ExampleResponse":
+        async for example_request in request_iterator:
+            return ExampleResponse(
+                example_string=example_request.example_string,
+                example_integer=example_request.example_integer,
+            )
+
+    async def example_stream_stream(
+        self, request_iterator: AsyncIterator["ExampleRequest"]
+    ) -> AsyncIterator["ExampleResponse"]:
+        async for example_request in request_iterator:
+            yield ExampleResponse(
+                example_string=example_request.example_string,
+                example_integer=example_request.example_integer,
+            )
+
+
+@pytest.mark.asyncio
+async def test_calls_with_different_cardinalities():
+    test_string = "test string"
+    test_int = 42
+
+    async with ChannelFor([ExampleService()]) as channel:
+        stub = TestStub(channel)
+
+        # unary unary
+        response = await stub.example_unary_unary(
+            example_string="test string",
+            example_integer=42,
+        )
+        assert response.example_string == test_string
+        assert response.example_integer == test_int
+
+        # unary stream
+        async for response in stub.example_unary_stream(
+            example_string="test string",
+            example_integer=42,
+        ):
+            assert response.example_string == test_string
+            assert response.example_integer == test_int
+
+        # stream unary
+        request = ExampleRequest(
+            example_string=test_string,
+            example_integer=42,
+        )
+
+        async def request_iterator():
+            yield request
+            yield request
+            yield request
+
+        response = await stub.example_stream_unary(request_iterator())
+        assert response.example_string == test_string
+        assert response.example_integer == test_int
+
+        # stream stream
+        async for response in stub.example_stream_stream(request_iterator()):
+            assert response.example_string == test_string
+            assert response.example_integer == test_int