Fix Trio imports on Android without interface helpers

newsfragments/3493.bugfix.rst

@@ -0,0 +1 @@
+Allow importing Trio on Android API levels where ``socket.if_indextoname`` and ``socket.if_nametoindex`` are unavailable.

src/trio/_tests/test_socket.py

@@ -4,6 +4,7 @@
 import inspect
 import os
 import socket as stdlib_socket
+import subprocess
 import sys
 import tempfile
 from pathlib import Path
@@ -167,6 +168,33 @@ def test_socket_has_some_reexports() -> None:
     assert tsocket.ntohs == stdlib_socket.ntohs
 
 
+def test_imports_without_android_interface_helpers() -> None:
+    script = """
+import socket as real_socket
+import sys
+import types
+
+fake_socket = types.ModuleType("socket")
+fake_socket.__dict__.update(real_socket.__dict__)
+del fake_socket.if_indextoname
+del fake_socket.if_nametoindex
+sys.modules["socket"] = fake_socket
+
+import trio.socket
+"""
+    environment = os.environ.copy()
+    source_path = str(Path(__file__).parents[2])
+    environment["PYTHONPATH"] = os.pathsep.join(
+        [source_path, environment.get("PYTHONPATH", "")]
+    )
+    subprocess.run(
+        [sys.executable, "-c", script],
+        cwd=Path(__file__).parents[3],
+        env=environment,
+        check=True,
+    )
+
+
 ################################################################
 # name resolution
 ################################################################

src/trio/socket.py

@@ -69,10 +69,12 @@
 )
 
 if sys.implementation.name == "cpython":
-    from socket import (
-        if_indextoname as if_indextoname,
-        if_nametoindex as if_nametoindex,
-    )
+    # These functions are not available on all Android API levels.
+    with _suppress(ImportError):
+        from socket import (
+            if_indextoname as if_indextoname,
+            if_nametoindex as if_nametoindex,
+        )
 
     # For android devices, if_nameindex support was introduced in API 24,
     # so it doesn't exist for any version prior.