Add tests to verify listener's IP/port binding

tests/test_listener.py

@@ -0,0 +1,38 @@
+import pytest
+
+import ucp
+
+
+@pytest.mark.asyncio
+async def test_bind_ip():
+    listener = ucp.create_listener(lambda: None, ip_address="127.0.0.1")
+
+    assert isinstance(listener.port, int)
+    assert listener.port >= 1024
+
+    assert isinstance(listener.ip, str)
+    assert listener.ip == "127.0.0.1"
+
+
+@pytest.mark.asyncio
+async def test_bind_port():
+    listener = None
+    port = None
+
+    for i in range(10000, 20000):
+        try:
+            listener = ucp.create_listener(
+                lambda: None,
+                i,
+            )
+        except ucp.UCXError:
+            # Port already in use, try another
+            continue
+        else:
+            port = i
+            break
+
+    assert isinstance(listener.port, int)
+    assert listener.port == port
+
+    assert isinstance(listener.ip, str)