VUnit · LarsAsplund · May 9, 2025 · May 6, 2025
diff --git a/docs/news.d/1113.feature.rst b/docs/news.d/1113.feature.rst
@@ -0,0 +1 @@
+Added support for repeating seeds from previous test run by setting the ``--seed`` option to ``repeat``.
diff --git a/docs/run/user_guide.rst b/docs/run/user_guide.rst
@@ -295,6 +295,8 @@ To reproduce the failing test setup and verify a bug fix, the failing seed can b
 .. raw:: html
     :file: img/seed_option.html
 
+``--seed`` can also be set to ``repeat``, in which case the values from the previous test run will be repeated.
+
 Running A VUnit Testbench Standalone
 ------------------------------------
 

diff --git a/tests/acceptance/artificial/vhdl/reference_test_history/0 b/tests/acceptance/artificial/vhdl/reference_test_history/0
diff --git a/tests/acceptance/artificial/vhdl/reference_test_history/1 b/tests/acceptance/artificial/vhdl/reference_test_history/1
diff --git a/tests/acceptance/artificial/vhdl/run.py b/tests/acceptance/artificial/vhdl/run.py
@@ -164,6 +164,15 @@ def pre_config(output_path):
     for idx, (extra_time, fail) in enumerate([(5, False), (2, True)], 1):
         tb.add_config(name=f"test_{idx}", pre_config=make_pre_config(idx, extra_time, fail))
 
+def configure_tb_seed(ui):
+    tb = ui.library("lib").test_bench("tb_seed")
+
+    if args.seed == "0123456789abcdef":
+        tb.test("test_1").set_generic("expected_seed", "2e373913e5ad677d")
+        tb.test("test_2").set_generic("expected_seed", "2e373913e5ad677d")
+    elif args.seed == "repeat":
+        tb.test("test_1").set_generic("expected_seed", "ffa08cd9489aad14")
+        tb.test("test_2").set_generic("expected_seed", "9a292b3679afd081")
 
 configure_tb_with_generic_config()
 configure_tb_same_sim_all_pass(vu)
@@ -172,6 +181,7 @@ def pre_config(output_path):
 configure_tb_with_vhdl_configuration(vu)
 configure_tb_no_fail_on_warning(vu)
 configure_tb_test_prio(vu)
+configure_tb_seed(vu)
 lib.entity("tb_no_generic_override").set_generic("g_val", False)
 lib.entity("tb_ieee_warning").test("pass").set_sim_option("disable_ieee_warnings", True)
 lib.entity("tb_other_file_tests").scan_tests_from_file(str(root / "other_file_tests.vhd"))

diff --git a/tests/acceptance/artificial/vhdl/tb_seed.vhd b/tests/acceptance/artificial/vhdl/tb_seed.vhd
@@ -0,0 +1,47 @@
+-- This Source Code Form is subject to the terms of the Mozilla Public
+-- License, v. 2.0. If a copy of the MPL was not distributed with this file,
+-- You can obtain one at http://mozilla.org/MPL/2.0/.
+--
+-- Copyright (c) 2014-2025, Lars Asplund [email protected]
+
+-- This attribute should be ignored when VHDL assert stop level is used
+-- vunit: fail_on_warning
+
+library vunit_lib;
+context vunit_lib.vunit_context;
+
+entity tb_seed is
+  generic (
+    runner_cfg : string;
+    expected_seed : string := ""
+  );
+end entity;
+
+architecture tb of tb_seed is
+  constant seed : string := get_seed(runner_cfg);
+begin
+  test_runner : process
+  begin
+    test_runner_setup(runner, runner_cfg);
+    show(display_handler, pass);
+
+    while test_suite loop
+      if expected_seed = "" then
+        -- Not expecting the seed derived from --seed=0123456789abcdef
+        check(seed /= "2e373913e5ad677d");
+      else
+        check_equal(seed, expected_seed);
+      end if;
+
+      if run("test_1") then
+        -- Not expecting the seed derived from --seed=repeat
+        check_implication(expected_seed = "", seed /= "ffa08cd9489aad14");
+      elsif run("test_2") then
+        -- Not expecting the seed derived from --seed=repeat
+        check_implication(expected_seed = "", seed /= "9a292b3679afd081");
+      end if;
+    end loop;
+
+    test_runner_cleanup(runner);
+  end process;
+end architecture;
diff --git a/tests/acceptance/test_artificial.py b/tests/acceptance/test_artificial.py
@@ -87,6 +87,26 @@ def test_artificial_changed(self):
             ],
         )
 
+    def test_hardcoded_seed(self):
+        self.check(self.artificial_run_vhdl, args=["lib.tb_seed*", "--seed=0123456789AbCdEf"])
+        check_report(
+            self.report_file,
+            [
+                ("passed", "lib.tb_seed.test_1"),
+                ("passed", "lib.tb_seed.test_2"),
+            ],
+        )
+
+    def test_repeated_seed(self):
+        self.check(self.artificial_run_vhdl, args=["lib.tb_seed*", "--seed=repeat"])
+        check_report(
+            self.report_file,
+            [
+                ("passed", "lib.tb_seed.test_1"),
+                ("passed", "lib.tb_seed.test_2"),
+            ],
+        )
+
     def _test_artificial(self, args=None):
         """
         Utility function to run and check the result of all test benches
@@ -289,4 +309,6 @@ def test_exit_0_flag(self):
     ("passed", "lib.tb_test_prio_1.test_4"),
     ("passed", "lib.tb_test_prio_2.test_1"),
     ("failed", "lib.tb_test_prio_2.test_2"),
+    ("passed", "lib.tb_seed.test_1"),
+    ("passed", "lib.tb_seed.test_2"),
 )
diff --git a/tests/unit/test_test_bench.py b/tests/unit/test_test_bench.py
@@ -27,6 +27,7 @@
     FileLocation,
     Attribute,
     LegacyAttribute,
+    _get_historic_seed,
 )
 from vunit.configuration import AttributeException
 from vunit.ostools import write_file
@@ -483,7 +484,7 @@ def test_error_on_global_attributes_from_python_on_tests(self, tempdir):
 
         test_bench = TestBench(design_unit)
         test = test_bench.get_test_case("Test 1")
-        self.assertRaises(AttributeException, test.set_attribute, "run_all_in_same_sim", True)    
+        self.assertRaises(AttributeException, test.set_attribute, "run_all_in_same_sim", True)
 
     @with_tempdir
     def test_test_information(self, tempdir):
@@ -904,6 +905,19 @@ def assert_has_tests(self, test_list, tests):
                 self.assertEqual(test1.name, test2)
                 self.assertEqual(test1.test_names, [test2])
 
+    def test_seed_from_test_history(self):
+        test_history = dict(test_suite1=dict(test1=dict(seed="11"), test2=dict(seed="12")), test_suite2=dict())
+
+        self.assertEqual(_get_historic_seed(test_history, test_suite_name="test_suite1"), "11")
+        self.assertEqual(_get_historic_seed(test_history, test_suite_name="test_suite1", test_name="test2"), "12")
+
+    def test_no_seed_from_test_history(self):
+        test_history = dict(test_suite1=dict(test1=dict(seed="11"), test2=dict(seed="12")), test_suite2=dict())
+
+        self.assertIsNone(_get_historic_seed(test_history, test_suite_name="foo"))
+        self.assertIsNone(_get_historic_seed(test_history, test_suite_name="test_suite1", test_name="test3"))
+        self.assertIsNone(_get_historic_seed(test_history, test_suite_name="test_suite2"))
+
     @staticmethod
     def create_tests(test_bench):
         """

diff --git a/tests/unit/test_test_report.py b/tests/unit/test_test_report.py
@@ -289,7 +289,13 @@ def test_junit_report_with_some_skipped_tests(self):
     def test_junit_report_with_testcase_classname(self):
         report = self._new_report()
         report.add_result(
-            "test", PASSED, time=1.0, output_file_name=self.output_file_name, test_suite_name="test", start_time=0
+            "test",
+            PASSED,
+            time=1.0,
+            output_file_name=self.output_file_name,
+            test_suite_name="test",
+            start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "lib.entity",
@@ -298,6 +304,7 @@ def test_junit_report_with_testcase_classname(self):
             output_file_name=self.output_file_name,
             test_suite_name="lib.entity",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "lib.entity.test",
@@ -306,6 +313,7 @@ def test_junit_report_with_testcase_classname(self):
             output_file_name=self.output_file_name,
             test_suite_name="lib.entity.test",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "lib.entity.config.test",
@@ -314,6 +322,7 @@ def test_junit_report_with_testcase_classname(self):
             output_file_name=self.output_file_name,
             test_suite_name="lib.entity.config.test",
             start_time=0,
+            seed="0123456789abcdef",
         )
         root = ElementTree.fromstring(report.to_junit_xml_str())
         names = set(
@@ -372,6 +381,7 @@ def _report_with_all_passed_tests(self, output_file_name=None):
             output_file_name=output_file_name,
             test_suite_name="passed_test0",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "passed_test1",
@@ -380,6 +390,7 @@ def _report_with_all_passed_tests(self, output_file_name=None):
             output_file_name=output_file_name,
             test_suite_name="passed_test0",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.set_expected_num_tests(2)
         return report
@@ -394,6 +405,7 @@ def _report_with_missing_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="passed_test0",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "passed_test1",
@@ -402,6 +414,7 @@ def _report_with_missing_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="passed_test0",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.set_expected_num_tests(3)
         return report
@@ -416,6 +429,7 @@ def _report_with_some_failed_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="failed_test0",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "passed_test",
@@ -424,6 +438,7 @@ def _report_with_some_failed_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="passed_test",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "failed_test1",
@@ -432,6 +447,7 @@ def _report_with_some_failed_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="failed_test1",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.set_expected_num_tests(3)
         return report
@@ -446,6 +462,7 @@ def _report_with_some_skipped_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="passed_test",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "skipped_test",
@@ -454,6 +471,7 @@ def _report_with_some_skipped_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="skipped_test",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "failed_test",
@@ -462,6 +480,7 @@ def _report_with_some_skipped_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="failed_test",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.set_expected_num_tests(3)
         return report
@@ -476,6 +495,7 @@ def _report_with_mixed_length_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="passed_test0",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "passed_test1",
@@ -484,6 +504,7 @@ def _report_with_mixed_length_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="passed_test1",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "passed_test2",
@@ -492,6 +513,7 @@ def _report_with_mixed_length_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="passed_test2",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "passed_test3",
@@ -500,6 +522,7 @@ def _report_with_mixed_length_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="passed_test3",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.set_expected_num_tests(4)
         return report
@@ -514,6 +537,7 @@ def _report_with_long_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="passed_test0",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "passed_test1",
@@ -522,6 +546,7 @@ def _report_with_long_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="passed_test1",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "passed_test2",
@@ -530,6 +555,7 @@ def _report_with_long_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="passed_test2",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "passed_test3",
@@ -538,6 +564,7 @@ def _report_with_long_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="passed_test3",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "passed_test4",
@@ -546,6 +573,7 @@ def _report_with_long_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="passed_test4",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.add_result(
             "passed_test5",
@@ -554,6 +582,7 @@ def _report_with_long_tests(self):
             output_file_name=self.output_file_name,
             test_suite_name="passed_test5",
             start_time=0,
+            seed="0123456789abcdef",
         )
         report.set_expected_num_tests(6)
         return report

diff --git a/tests/unit/test_test_runner.py b/tests/unit/test_test_runner.py
@@ -256,3 +256,6 @@ def run(self, output_path, read_output):
         self.output_path = output_path
         self.read_output = read_output
         return self.run_side_effect(output_path=output_path, read_output=read_output)
+
+    def get_seed(self):
+        return "0123456789abcdef"
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Added support for repeating seeds from previous test run by setting the ``--seed`` option to ``repeat``.