diff --git a/tests/copyright/policy b/tests/copyright/policy
index 38c97c7dd61..441284fd524 100644
--- a/tests/copyright/policy
+++ b/tests/copyright/policy
@@ -252,6 +252,7 @@ tests/light/functional_tests/logpath/test_midpoint_destinations\.py
 tests/light/functional_tests/value-pairs/test_value_pairs\.py
 tests/light/functional_tests/templates/test_template_stmt\.py
 tests/light/functional_tests/filterx/test_filterx\.py
+tests/light/functional_tests/filterx/test_filterx_scope\.py
 tests/light/functional_tests/parsers/metrics-probe/test_metrics_probe\.py
 tests/light/src/syslog_ng_ctl/prometheus_stats_handler.py
 tests/light/src/syslog_ng_config/statements/template/template\.py
diff --git a/tests/light/functional_tests/filterx/test_filterx_scope.py b/tests/light/functional_tests/filterx/test_filterx_scope.py
new file mode 100644
index 00000000000..a4c126c54ef
--- /dev/null
+++ b/tests/light/functional_tests/filterx/test_filterx_scope.py
@@ -0,0 +1,241 @@
+#!/usr/bin/env python
+#############################################################################
+# Copyright (c) 2023 Balazs Scheidler <balazs.scheidler@axoflow.com>
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License version 2 as published
+# by the Free Software Foundation, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#
+# As an additional exemption you are allowed to compile & link against the
+# OpenSSL libraries as published by the OpenSSL project. See the file
+# COPYING for details.
+#
+#############################################################################
+from src.syslog_ng_config.renderer import render_statement
+
+
+def render_filterx_exprs(expressions):
+    return '\n'.join(f"filterx {{ { expr } }};" for expr in expressions)
+
+
+def create_config(config, init_exprs, true_exprs=(), false_exprs=(), msg="foobar"):
+    file_true = config.create_file_destination(file_name="dest-true.log", template="'$MSG\n'")
+    file_false = config.create_file_destination(file_name="dest-false.log", template="'$MSG\n'")
+
+    preamble = f"""
+@version: {config.get_version()}
+
+options {{ stats(level(1)); }};
+
+source genmsg {{
+    example-msg-generator(
+        num(1)
+        template("{msg}")
+        values(
+            "values.str" => string("string"),
+            "values.bool" => boolean(true),
+            "values.int" => int(5),
+            "values.double" => double(32.5),
+            "values.datetime" => datetime("1701350398.123000+01:00"),
+            "values.list" => list("foo,bar,baz"),
+            "values.null" => null(""),
+            "values.bytes" => bytes("binary whatever"),
+            "values.protobuf" => protobuf("this is not a valid protobuf!!"),
+            "values.json" => json('{{"emb_key1": "emb_key1 value", "emb_key2": "emb_key2 value"}}'),
+            "values.true_string" => string("boolean:true"),
+            "values.false_string" => string("boolean:false"),
+        )
+    );
+}};
+
+destination dest_true {{
+    {render_statement(file_true)};
+}};
+
+destination dest_false {{
+    {render_statement(file_false)};
+}};
+
+log {{
+    source(genmsg);
+    {render_filterx_exprs(init_exprs)};
+    if {{
+        {render_filterx_exprs(true_exprs)}
+        destination(dest_true);
+    }} else {{
+        {render_filterx_exprs(false_exprs)}
+        destination(dest_false);
+    }};
+}};
+"""
+    config.set_raw_config(preamble)
+    return (file_true, file_false)
+
+
+def test_message_tied_variables_are_propagated_to_the_output(config, syslog_ng):
+    (file_true, file_false) = create_config(
+        config, [
+"""
+$foo = "kecske";
+isset($foo);
+""",
+"""
+isset($foo);
+$MSG = $foo;
+""",
+        ],
+    )
+    syslog_ng.start(config)
+
+    assert file_true.get_stats()["processed"] == 1
+    assert "processed" not in file_false.get_stats()
+    assert file_true.read_log() == "kecske\n"
+
+
+def test_message_tied_variables_are_propagated_to_the_output_in_junctions(config, syslog_ng):
+    (file_true, file_false) = create_config(
+        config, init_exprs=[
+"""
+$foo = "kecske";
+isset($foo);
+""",
+        ], true_exprs=[
+"""
+isset($foo);
+$MSG = $foo;
+""",
+        ],
+    )
+    syslog_ng.start(config)
+
+    assert file_true.get_stats()["processed"] == 1
+    assert "processed" not in file_false.get_stats()
+    assert file_true.read_log() == "kecske\n"
+
+
+def test_message_tied_variables_do_not_propagate_to_parallel_branches(config, syslog_ng):
+    (file_true, file_false) = create_config(
+        config, init_exprs=[
+"""
+$foo = "kecske";
+isset($foo);
+""",
+        ], true_exprs=[
+"""
+isset($foo);
+$bar = $foo;
+isset($bar);
+$foo = "not kecske";
+false;
+""",
+        ], false_exprs=[
+"""
+isset($foo);
+not isset($bar);
+$MSG = $foo;
+""",
+        ],
+    )
+    syslog_ng.start(config)
+
+    assert file_false.get_stats()["processed"] == 1
+    assert "processed" not in file_true.get_stats()
+    assert file_false.read_log() == "kecske\n"
+
+
+def test_floating_variables_are_dropped_at_the_end_of_the_scope(config, syslog_ng):
+    (file_true, file_false) = create_config(
+        config, [
+"""
+foo = "kecske";
+isset(foo);
+""",
+"""
+not isset(foo);
+""",
+        ],
+    )
+    syslog_ng.start(config)
+
+    assert file_true.get_stats()["processed"] == 1
+    assert "processed" not in file_false.get_stats()
+    assert file_true.read_log() == "foobar\n"
+
+
+def test_floating_variables_are_dropped_at_the_end_of_the_scope_but_can_be_recreated(config, syslog_ng):
+    (file_true, file_false) = create_config(
+        config, [
+"""
+foo = "kecske";
+isset(foo);
+""",
+"""
+not isset(foo);
+foo = "barka";
+isset(foo);
+$MSG = foo;
+""",
+        ],
+    )
+    syslog_ng.start(config)
+
+    assert file_true.get_stats()["processed"] == 1
+    assert "processed" not in file_false.get_stats()
+    assert file_true.read_log() == "barka\n"
+
+
+def test_declared_variables_are_retained_across_scopes(config, syslog_ng):
+    (file_true, file_false) = create_config(
+        config, [
+"""
+declare foo = "kecske";
+isset(foo);
+""",
+"""
+isset(foo);
+foo = "barka";
+""",
+"""
+isset(foo);
+$MSG = foo;
+""",
+        ],
+    )
+    syslog_ng.start(config)
+
+    assert file_true.get_stats()["processed"] == 1
+    assert "processed" not in file_false.get_stats()
+    assert file_true.read_log() == "barka\n"
+
+
+def test_declared_variables_are_retained_across_scopes_and_junctions(config, syslog_ng):
+    (file_true, file_false) = create_config(
+        config, init_exprs=[
+"""
+declare foo = "kecske";
+isset(foo);
+"""], true_exprs=[
+"""
+isset(foo);
+foo = "barka";
+""",
+"""
+isset(foo);
+$MSG = foo;
+""",
+        ],
+    )
+    syslog_ng.start(config)
+
+    assert file_true.get_stats()["processed"] == 1
+    assert "processed" not in file_false.get_stats()
+    assert file_true.read_log() == "barka\n"