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https://github.com/kataev/pytest-grpc

Allow test gRPC with pytest
https://github.com/kataev/pytest-grpc

pytest pytest-plugin

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Allow test gRPC with pytest

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# pytest-grpc

Write test for gRPC with pytest.

## Example

See example dir and/or read 'usage'.

## Usage

For example you have some proto file with rpc declaration.

```proto
syntax = "proto3";

package test.v1;

service EchoService {
rpc handler(EchoRequest) returns (EchoResponse) {
}
}

message EchoRequest {
string name = 1;
}

message EchoResponse {
string name = 1;
}

```

After compile it with grpcio-tools, you get *_pb2.py and *_pb2_grpc.py files, now you can write your service.

```python
from stub.test_pb2 import EchoRequest, EchoResponse
from stub.test_pb2_grpc import EchoServiceServicer

class Servicer(EchoServiceServicer):
def handler(self, request: EchoRequest, context) -> EchoResponse:
return EchoResponse(name=f'test-{request.name}')

def error_handler(self, request: EchoRequest, context) -> EchoResponse:
raise RuntimeError('Some error')
```

Point pytest with your stubs and service:

```python
import pytest

from stub.test_pb2 import EchoRequest

@pytest.fixture(scope='module')
def grpc_add_to_server():
from stub.test_pb2_grpc import add_EchoServiceServicer_to_server

return add_EchoServiceServicer_to_server

@pytest.fixture(scope='module')
def grpc_servicer():
from servicer import Servicer

return Servicer()

@pytest.fixture(scope='module')
def grpc_stub_cls(grpc_channel):
from stub.test_pb2_grpc import EchoServiceStub

return EchoServiceStub
```

Write little test:
```python

def test_some(grpc_stub):
request = EchoRequest()
response = grpc_stub.handler(request)

assert response.name == f'test-{request.name}'

def test_example(grpc_stub):
request = EchoRequest()
response = grpc_stub.error_handler(request)

assert response.name == f'test-{request.name}'
```

#### Testing secure server

```python
from pathlib import Path
import pytest
import grpc

@pytest.fixture(scope='module')
def grpc_add_to_server():
from stub.test_pb2_grpc import add_EchoServiceServicer_to_server

return add_EchoServiceServicer_to_server

@pytest.fixture(scope='module')
def grpc_servicer():
from servicer import Servicer

return Servicer()

@pytest.fixture(scope='module')
def grpc_stub_cls(grpc_channel):
from stub.test_pb2_grpc import EchoServiceStub

return EchoServiceStub

@pytest.fixture(scope='session')
def my_ssl_key_path():
return Path('/path/to/key.pem')

@pytest.fixture(scope='session')
def my_ssl_cert_path():
return Path('/path/to/cert.pem')

@pytest.fixture(scope='module')
def grpc_server(_grpc_server, grpc_addr, my_ssl_key_path, my_ssl_cert_path):
"""
Overwrites default `grpc_server` fixture with ssl credentials
"""
credentials = grpc.ssl_server_credentials([
(my_ssl_key_path.read_bytes(),
my_ssl_cert_path.read_bytes())
])

_grpc_server.add_secure_port(grpc_addr, server_credentials=credentials)
_grpc_server.start()
yield _grpc_server
_grpc_server.stop(grace=None)

@pytest.fixture(scope='module')
def my_channel_ssl_credentials(my_ssl_cert_path):
# If we're using self-signed certificate it's necessarily to pass root certificate to channel
return grpc.ssl_channel_credentials(
root_certificates=my_ssl_cert_path.read_bytes()
)

@pytest.fixture(scope='module')
def grpc_channel(my_channel_ssl_credentials, create_channel):
"""
Overwrites default `grpc_channel` fixture with ssl credentials
"""
with create_channel(my_channel_ssl_credentials) as channel:
yield channel


@pytest.fixture(scope='module')
def grpc_authorized_channel(my_channel_ssl_credentials, create_channel):
"""
Channel with authorization header passed
"""
grpc_channel_credentials = grpc.access_token_call_credentials("some_token")
composite_credentials = grpc.composite_channel_credentials(
my_channel_ssl_credentials,
grpc_channel_credentials
)
with create_channel(composite_credentials) as channel:
yield channel


@pytest.fixture(scope='module')
def my_authorized_stub(grpc_stub_cls, grpc_channel):
"""
Stub with authorized channel
"""
return grpc_stub_cls(grpc_channel)

```

## Run tests against real gRPC server
Run tests against read grpc server worked in another thread:

```bash
py.test
```

```
cachedir: .pytest_cache
plugins: grpc-0.0.0
collected 2 items

example/test_example.py::test_some PASSED
example/test_example.py::test_example FAILED

=================================== FAILURES ====================================
_________________________________ test_example __________________________________

grpc_stub =

def test_example(grpc_stub):
request = EchoRequest()
> response = grpc_stub.error_handler(request)

example/test_example.py:35:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
.env/lib/python3.7/site-packages/grpc/_channel.py:547: in __call__
return _end_unary_response_blocking(state, call, False, None)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

state =
call =
with_call = False, deadline = None

def _end_unary_response_blocking(state, call, with_call, deadline):
if state.code is grpc.StatusCode.OK:
if with_call:
rendezvous = _Rendezvous(state, call, None, deadline)
return state.response, rendezvous
else:
return state.response
else:
> raise _Rendezvous(state, None, None, deadline)
E grpc._channel._Rendezvous: <_Rendezvous of RPC that terminated with:
E status = StatusCode.UNKNOWN
E details = "Exception calling application: Some error"
E debug_error_string = "{"created":"@1544451353.148337000","description":"Error received from peer","file":"src/core/lib/surface/call.cc","file_line":1036,"grpc_message":"Exception calling application: Some error","grpc_status":2}"
E >

.env/lib/python3.7/site-packages/grpc/_channel.py:466: _Rendezvous
------------------------------- Captured log call -------------------------------
_server.py 397 ERROR Exception calling application: Some error
Traceback (most recent call last):
File "pytest-grpc/.env/lib/python3.7/site-packages/grpc/_server.py", line 389, in _call_behavior
return behavior(argument, context), True
File "pytest-grpc/example/src/servicer.py", line 10, in error_handler
raise RuntimeError('Some error')
RuntimeError: Some error
================ 1 failed, 1 passed, 1 warnings in 0.16 seconds =================

```

## Run tests directly to python code
Call handlers directly, with fake grpc internals:

```bash
py.test --grpc-fake-server
```

In this case your get nice direct exceptions:

```
============================= test session starts =============================
cachedir: .pytest_cache
plugins: grpc-0.0.0
collected 2 items

example/test_example.py::test_some PASSED
example/test_example.py::test_example FAILED

================================== FAILURES ===================================
________________________________ test_example _________________________________

grpc_stub =

def test_example(grpc_stub):
request = EchoRequest()
> response = grpc_stub.error_handler(request)

example/test_example.py:35:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
pytest_grpc/plugin.py:42: in fake_handler
return real_method(request, context)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = , request =
context =

def error_handler(self, request: EchoRequest, context) -> EchoResponse:
> raise RuntimeError('Some error')
E RuntimeError: Some error

example/src/servicer.py:10: RuntimeError
=============== 1 failed, 1 passed, 1 warnings in 0.10 seconds ================
```

## Run the servicer on multiple threads
The number of workers threads for gRPC can be specified in two ways:

- add `--grpc-max-workers=` to the arguments
- test modules can also use a `grpc_max_workers=` variable

See `test_blocking` in example.