Display an actual TCP port app is bound to (#3034)

test/io/test_io.py

@@ -197,6 +197,13 @@ def test_flush_pool_no_interrupt(defaultenv):
         t.join()
 
 
+def test_random_port_bound(defaultenv):
+    "PostgREST should bind to a random port when PGRST_SERVER_PORT is 0."
+
+    with run(env=defaultenv, port="0") as postgrest:
+        assert True  # liveness check is done by run(), so we just need to check that it doesn't fail
+
+
 def test_app_settings_reload(tmp_path, defaultenv):
     "App settings should be reloaded from file when PostgREST is sent SIGUSR2."
     config = (CONFIGSDIR / "sigusr2-settings.config").read_text()