python310Packages.psycopg: Test against a live postgresql instance

provided by postgresqlTestHook. Extends our test coverage on Linux from
250 to over 4000 tests, that run in a reasonable time.

pkgs/development/python-modules/psycopg/default.nix

@@ -30,6 +30,7 @@
 , pproxy
 , pytest-randomly
 , pytestCheckHook
+, postgresqlTestHook
 }:
 
 let
@@ -165,10 +166,6 @@ buildPythonPackage rec {
     pool = [ psycopg-pool ];
   };
 
-  preCheck = ''
-    cd ..
-  '';
-
   nativeCheckInputs = [
     anyio
     pproxy
@@ -176,9 +173,21 @@ buildPythonPackage rec {
     pytestCheckHook
     postgresql
   ]
+  ++ lib.optional (stdenv.isLinux) postgresqlTestHook
   ++ passthru.optional-dependencies.c
   ++ passthru.optional-dependencies.pool;
 
+  env = {
+    postgresqlEnableTCP = 1;
+    PGUSER = "psycopg";
+  };
+
+  preCheck = ''
+    cd ..
+  '' + lib.optionalString (stdenv.isLinux) ''
+    export PSYCOPG_TEST_DSN="host=127.0.0.1 user=$PGUSER"
+  '';
+
   disabledTests = [
     # don't depend on mypy for tests
     "test_version"