diff --git a/nix/ext/tests/default.nix b/nix/ext/tests/default.nix
index 8777a72587..ce2b21a74f 100644
--- a/nix/ext/tests/default.nix
+++ b/nix/ext/tests/default.nix
@@ -215,13 +215,26 @@ let
               ""
           }
 
+          has_update_script = False
           with subtest("switch to postgresql 17"):
             server.succeed(
               f"{pg17_configuration}/bin/switch-to-configuration test >&2"
             )
+            server.wait_for_unit("postgresql.service")
+            has_update_script = server.succeed(
+              "test -f /var/lib/postgresql/update_extensions.sql && echo 'yes' || echo 'no'"
+            ).strip() == "yes"
+            if has_update_script:
+              # Run the extension update script generated during the upgrade
+              test.run_sql_file("/var/lib/postgresql/update_extensions.sql")
 
           with subtest("Check last version of the extension after postgresql upgrade"):
-            test.assert_version_matches(last_version)
+            if has_update_script:
+              # If there was an update script, the last version should be installed
+              test.assert_version_matches(versions["17"][-1])
+            else:
+              # Otherwise, the version should match the last version from postgresql 15
+              test.assert_version_matches(last_version)
 
           ${
             if support_upgrade then
@@ -271,11 +284,12 @@ builtins.listToAttrs (
       "pg_hashids"
       "pg_jsonschema"
       "pg_net"
+      "pg_partman"
       "pg_repack"
       "pg_stat_monitor"
       "pg_tle"
       "pgaudit"
-      "pg_partman"
+      "postgis"
       "vector"
       "wal2json"
       "wrappers"
diff --git a/nix/ext/tests/http.nix b/nix/ext/tests/http.nix
index fab6a0d204..22bd45c473 100644
--- a/nix/ext/tests/http.nix
+++ b/nix/ext/tests/http.nix
@@ -166,3 +166,6 @@ self.inputs.nixpkgs.lib.nixos.runTest {
       check_upgrade_path("17")
     '';
 }
+# We don't use the generic test for this extension because:
+# http is not using semver versioning scheme, so we need to adapt the version checks
+# otherwise the test fails with ERROR:  extension "http" has no installation script nor update path for version "1.5.0"
diff --git a/nix/ext/tests/postgis.nix b/nix/ext/tests/pg_repack.nix
similarity index 66%
rename from nix/ext/tests/postgis.nix
rename to nix/ext/tests/pg_repack.nix
index 7599ab7c99..c81e29b2d1 100644
--- a/nix/ext/tests/postgis.nix
+++ b/nix/ext/tests/pg_repack.nix
@@ -1,6 +1,6 @@
 { self, pkgs }:
 let
-  pname = "postgis";
+  pname = "pg_repack";
   inherit (pkgs) lib;
   installedExtension =
     postgresMajorVersion:
@@ -64,8 +64,25 @@ self.inputs.nixpkgs.lib.nixos.runTest {
       services.postgresql = {
         enable = true;
         package = postgresqlWithExtension self.packages.${pkgs.stdenv.hostPlatform.system}.postgresql_15;
+        enableTCPIP = true;
+        authentication = ''
+          local all postgres peer map=postgres
+          local all all peer map=root
+        '';
+        identMap = ''
+          root root supabase_admin
+          postgres postgres postgres
+        '';
+        ensureUsers = [
+          {
+            name = "supabase_admin";
+            ensureClauses.superuser = true;
+          }
+        ];
       };
 
+      networking.firewall.allowedTCPPorts = [ config.services.postgresql.settings.port ];
+
       specialisation.postgresql17.configuration = {
         services.postgresql = {
           package = lib.mkForce (
@@ -117,52 +134,44 @@ self.inputs.nixpkgs.lib.nixos.runTest {
       pg17-configuration = "${nodes.server.system.build.toplevel}/specialisation/postgresql17";
     in
     ''
+      from pathlib import Path
       versions = {
         "15": [${lib.concatStringsSep ", " (map (s: ''"${s}"'') (versions "15"))}],
         "17": [${lib.concatStringsSep ", " (map (s: ''"${s}"'') (versions "17"))}],
       }
+      extension_name = "${pname}"
+      support_upgrade = False
+      pg17_configuration = "${pg17-configuration}"
+      sql_test_directory = Path("${../../tests}")
 
-      def run_sql(query):
-        return server.succeed(f"""sudo -u postgres psql -t -A -F\",\" -c \"{query}\" """).strip()
-
-      def check_upgrade_path(pg_version):
-        with subtest("Check ${pname} upgrade path"):
-          firstVersion = versions[pg_version][0]
-          server.succeed("sudo -u postgres psql -c 'DROP EXTENSION IF EXISTS ${pname};'")
-          run_sql(f"""CREATE EXTENSION ${pname} WITH VERSION '{firstVersion}' CASCADE;""")
-          installed_version = run_sql(r"""SELECT extversion FROM pg_extension WHERE extname = '${pname}';""")
-          assert installed_version == firstVersion, f"Expected ${pname} version {firstVersion}, but found {installed_version}"
-          for version in versions[pg_version][1:]:
-            run_sql(f"""ALTER EXTENSION ${pname} UPDATE TO '{version}';""")
-            installed_version = run_sql(r"""SELECT extversion FROM pg_extension WHERE extname = '${pname}';""")
-            assert installed_version == version, f"Expected ${pname} version {version}, but found {installed_version}"
+      ${builtins.readFile ./lib.py}
 
       start_all()
 
       server.wait_for_unit("multi-user.target")
       server.wait_for_unit("postgresql.service")
 
-      check_upgrade_path("15")
+      test = PostgresExtensionTest(server, extension_name, versions, sql_test_directory, support_upgrade)
+
+      with subtest("Check upgrade path with postgresql 15"):
+        test.check_upgrade_path("15")
 
-      with subtest("Check ${pname} latest extension version"):
-        server.succeed("sudo -u postgres psql -c 'DROP EXTENSION ${pname};'")
-        server.succeed("sudo -u postgres psql -c 'CREATE EXTENSION ${pname} CASCADE;'")
-        installed_extensions=run_sql(r"""SELECT extname, extversion FROM pg_extension where extname = '${pname}';""")
-        latestVersion = versions["15"][-1]
-        majMinVersion = ".".join(latestVersion.split('.')[:1])
-        assert f"${pname},{majMinVersion}" in installed_extensions, f"Expected ${pname} version {latestVersion}, but found {installed_extensions}"
+      last_version = None
+      with subtest("Check the install of the last version of the extension"):
+        last_version = test.check_install_last_version("15")
 
       with subtest("switch to postgresql 17"):
         server.succeed(
-          "${pg17-configuration}/bin/switch-to-configuration test >&2"
+          f"{pg17_configuration}/bin/switch-to-configuration test >&2"
         )
 
-      with subtest("Check ${pname} latest extension version after upgrade"):
-        installed_extensions=run_sql(r"""SELECT extname, extversion FROM pg_extension;""")
-        latestVersion = versions["17"][-1]
-        majMinVersion = ".".join(latestVersion.split('.')[:1])
-        assert f"${pname},{majMinVersion}" in installed_extensions
+      with subtest("Check last version of the extension after upgrade"):
+        test.assert_version_matches(last_version)
 
-      check_upgrade_path("17")
+      with subtest("Check upgrade path with postgresql 17"):
+        test.check_upgrade_path("17")
     '';
 }
+# We don't use the generic test for this extension because:
+# pg_repack does not support upgrade as the extension doesn't provide the upgrade SQL scripts
+# and fails with ERROR:  extension "pg_repack" has no update path from version "1.4.8" to version "1.5.0"
diff --git a/nix/ext/tests/pgrouting.nix b/nix/ext/tests/pgrouting.nix
index 15fac76c5d..5a023d5caa 100644
--- a/nix/ext/tests/pgrouting.nix
+++ b/nix/ext/tests/pgrouting.nix
@@ -242,3 +242,4 @@ self.inputs.nixpkgs.lib.nixos.runTest {
       check_upgrade_path("orioledb-17")
     '';
 }
+# We don't use the generic test for this extension because: it requires postgis to be installed as well.