separate out subprocess handling into subclass

deltachat-rpc-client/src/deltachat_rpc_client/rpc.py

@@ -10,7 +10,10 @@ import subprocess
 import sys
 from queue import Empty, Queue
 from threading import Thread
-from typing import Any, Iterator, Optional
+from typing import TYPE_CHECKING, Any, Iterator, Optional
+
+if TYPE_CHECKING:
+    import io
 
 
 class JsonRpcError(Exception):
@@ -51,18 +54,8 @@ class RpcMethod:
         return rpc_future
 
 
-class Rpc:
-    """RPC client."""
-
-    def __init__(self, accounts_dir: Optional[str] = None, rpc_server_path="deltachat-rpc-server"):
-        """Initialize RPC client.
-
-        The given arguments will be passed to subprocess.Popen().
-        """
-        self._accounts_dir = accounts_dir
-
-        self.rpc_server_path = rpc_server_path
-        self.process: subprocess.Popen
+class BaseRpc:
+    def __init__(self):
         self.id_iterator: Iterator[int]
         self.event_queues: dict[int, Queue]
         # Map from request ID to a Queue which provides a single result
@@ -75,7 +68,7 @@ class Rpc:
 
     def start(self) -> None:
         """Start RPC server subprocess."""
-        self.server_stdout, self.server_stdin = self.connect_to_subprocess()
+        self.server_stdout, self.server_stdin = self.connect_to_server()
         self.id_iterator = itertools.count(start=1)
         self.event_queues = {}
         self.request_results = {}
@@ -88,28 +81,11 @@ class Rpc:
         self.events_thread = Thread(target=self.events_loop)
         self.events_thread.start()
 
-    def connect_to_subprocess(self):
-        popen_kwargs = {"stdin": subprocess.PIPE, "stdout": subprocess.PIPE}
-        if sys.version_info >= (3, 11):
-            # Prevent subprocess from capturing SIGINT.
-            popen_kwargs["process_group"] = 0
-        else:
-            # `process_group` is not supported before Python 3.11.
-            popen_kwargs["preexec_fn"] = os.setpgrp  # noqa: PLW1509
-
-        if self._accounts_dir:
-            popen_kwargs["env"] = os.environ.copy()
-            popen_kwargs["env"]["DC_ACCOUNTS_PATH"] = str(self._accounts_dir)
-
-        process = subprocess.Popen(self.rpc_server_path, **popen_kwargs)
-        return process.stdout, process.stdin
-
     def close(self) -> None:
         """Terminate RPC server process and wait until the reader loop finishes."""
         self.closing = True
-        self.stop_io_for_all_accounts()
+        self.disconnect_from_server()
         self.events_thread.join()
-        self.server_stdin.close()
         self.reader_thread.join()
         self.request_queue.put(None)
         self.writer_thread.join()
@@ -185,3 +161,38 @@ class Rpc:
 
     def __getattr__(self, attr: str):
         return RpcMethod(self, attr)
+
+
+class Rpc(BaseRpc):
+    """RPC client that runs and connects to a deltachat-rpc-server in a subprocess."""
+
+    def __init__(self, accounts_dir: Optional[str] = None, rpc_server_path: Optional[str] = "deltachat-rpc-server"):
+        """Initialize RPC client.
+
+        The given arguments will be passed to subprocess.Popen().
+        """
+        super(Rpc, self).__init__()
+        self.server_stdout: io.Writer[bytes]
+        self.server_stdin: io.Reader[bytes]
+        self._accounts_dir = accounts_dir
+        self.rpc_server_path = rpc_server_path
+
+    def connect_to_server(self):
+        popen_kwargs = {"stdin": subprocess.PIPE, "stdout": subprocess.PIPE}
+        if sys.version_info >= (3, 11):
+            # Prevent subprocess from capturing SIGINT.
+            popen_kwargs["process_group"] = 0
+        else:
+            # `process_group` is not supported before Python 3.11.
+            popen_kwargs["preexec_fn"] = os.setpgrp  # noqa: PLW1509
+
+        if self._accounts_dir:
+            popen_kwargs["env"] = os.environ.copy()
+            popen_kwargs["env"]["DC_ACCOUNTS_PATH"] = str(self._accounts_dir)
+
+        process = subprocess.Popen(self.rpc_server_path, **popen_kwargs)
+        return process.stdout, process.stdin
+
+    def disconnect_from_server(self):
+        self.stop_io_for_all_accounts()
+        self.server_stdin.close()