feat: deltachat_rpc_client.Rpc accepts rpc_server_path for using a particular deltachat-rpc-server (#7493)

also simplifies and make more readable popen-call to rpc-server 

addresses #7428

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

@@ -54,7 +54,7 @@ class RpcMethod:
 class Rpc:
     """RPC client."""
 
-    def __init__(self, accounts_dir: Optional[str] = None, **kwargs):
+    def __init__(self, accounts_dir: Optional[str] = None, rpc_server_path="deltachat-rpc-server", **kwargs):
         """Initialize RPC client.
 
         The given arguments will be passed to subprocess.Popen().
@@ -66,6 +66,7 @@ class Rpc:
             }
 
         self._kwargs = kwargs
+        self.rpc_server_path = rpc_server_path
         self.process: subprocess.Popen
         self.id_iterator: Iterator[int]
         self.event_queues: dict[int, Queue]
@@ -79,24 +80,16 @@ class Rpc:
 
     def start(self) -> None:
         """Start RPC server subprocess."""
+        popen_kwargs = {"stdin": subprocess.PIPE, "stdout": subprocess.PIPE}
         if sys.version_info >= (3, 11):
-            self.process = subprocess.Popen(
-                "deltachat-rpc-server",
-                stdin=subprocess.PIPE,
-                stdout=subprocess.PIPE,
             # Prevent subprocess from capturing SIGINT.
-                process_group=0,
+            popen_kwargs["process_group"] = 0
-                **self._kwargs,
-            )
         else:
-            self.process = subprocess.Popen(
-                "deltachat-rpc-server",
-                stdin=subprocess.PIPE,
-                stdout=subprocess.PIPE,
             # `process_group` is not supported before Python 3.11.
-                preexec_fn=os.setpgrp,  # noqa: PLW1509
+            popen_kwargs["preexec_fn"] = os.setpgrp  # noqa: PLW1509
-                **self._kwargs,
+
-            )
+        popen_kwargs.update(self._kwargs)
+        self.process = subprocess.Popen(self.rpc_server_path, **popen_kwargs)
         self.id_iterator = itertools.count(start=1)
         self.event_queues = {}
         self.request_results = {}

deltachat-rpc-client/tests/test_rpc_virtual.py

@@ -0,0 +1,20 @@
+import subprocess
+import sys
+from platform import system  # noqa
+
+import pytest
+
+from deltachat_rpc_client import DeltaChat, Rpc
+
+
+@pytest.mark.skipif("system() == 'Windows'")
+def test_install_venv_and_use_other_core(tmp_path):
+    venv = tmp_path.joinpath("venv1")
+    subprocess.check_call([sys.executable, "-m", "venv", venv])
+    python = venv / "bin" / "python"
+    subprocess.check_call([python, "-m", "pip", "install", "deltachat-rpc-server==2.20.0"])
+    rpc = Rpc(accounts_dir=tmp_path.joinpath("accounts"), rpc_server_path=venv.joinpath("bin", "deltachat-rpc-server"))
+
+    with rpc:
+        dc = DeltaChat(rpc)
+        assert dc.rpc.get_system_info()["deltachat_core_version"] == "v2.20.0"