feat(unity): Adds unit test ordering by file path and line number

Closes https://github.com/espressif/esp-idf/issues/15529

components/unity/Kconfig

@@ -58,4 +58,18 @@ menu "Unity unit testing library"
             jumping back to the test menu. The jumping is usually occurs in assert
             functions such as TEST_ASSERT, TEST_FAIL etc.
 
+    config UNITY_TEST_ORDER_BY_FILE_PATH_AND_LINE
+        bool "Order unit tests by file path and line number"
+        default n
+        help
+            If enabled, the Unity test framework will automatically insert test cases
+            in a sorted order at registration time (during constructor execution),
+            based on their source file path and line number.
+
+            This ensures consistent execution order across platforms (e.g., Linux vs. on-chip),
+            preserving the logical order in which tests are written in the source files.
+
+            Note, the file path used for sorting follows the full absolute path format.
+            /IDF/examples/system/unit_test/components/testable/test/test_mean.c
+
 endmenu # "Unity unit testing library"

components/unity/test_apps/.build-test-rules.yml

@@ -0,0 +1,8 @@
+# Documentation: .gitlab/ci/README.md#manifest-file-to-control-the-buildtest-apps
+
+components/unity/test_apps:
+  enable:
+    - if: IDF_TARGET in["esp32", "linux"]
+      reason: need to test on a chip and linux targets
+  depends_components:
+    - unity

components/unity/test_apps/CMakeLists.txt

@@ -0,0 +1,7 @@
+#This is the project CMakeLists.txt file for the test subproject
+cmake_minimum_required(VERSION 3.16)
+
+set(COMPONENTS main)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(unity_test_app)

components/unity/test_apps/README.md

@@ -0,0 +1,2 @@
+| Supported Targets | ESP32 | Linux |
+| ----------------- | ----- | ----- |

components/unity/test_apps/main/CMakeLists.txt

@@ -0,0 +1,3 @@
+idf_component_register(SRC_DIRS "."
+                       PRIV_REQUIRES unity
+                       WHOLE_ARCHIVE)

components/unity/test_apps/main/test.c

@@ -0,0 +1,26 @@
+/*
+ * SPDX-FileCopyrightText: 2025 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include "unity.h"
+
+TEST_CASE("Test 1", "[test]")
+{
+    TEST_ASSERT(1 == 1);
+}
+
+TEST_CASE("Test 2", "[test]")
+{
+    TEST_ASSERT(1 == 1);
+}
+
+TEST_CASE("Test 3", "[test]")
+{
+    TEST_ASSERT(1 == 1);
+}
+
+TEST_CASE("Test 4", "[test]")
+{
+    TEST_ASSERT(1 == 1);
+}

components/unity/test_apps/main/test_app_main.c

@@ -0,0 +1,11 @@
+/*
+ * SPDX-FileCopyrightText: 2025 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Unlicense OR CC0-1.0
+ */
+#include "unity.h"
+
+void app_main(void)
+{
+    unity_run_menu();
+}

components/unity/test_apps/pytest_unit_test.py

@@ -0,0 +1,26 @@
+# SPDX-FileCopyrightText: 2025 Espressif Systems (Shanghai) CO LTD
+# SPDX-License-Identifier: CC0-1.0
+import pytest
+from pytest_embedded import Dut
+from pytest_embedded_idf.utils import idf_parametrize
+
+
+def verify_test_order(dut: Dut) -> None:
+    dut.expect_exact('Press ENTER to see the list of tests.')
+    dut.write('\n')
+    dut.expect('Test 1')
+    dut.expect('Test 2')
+    dut.expect('Test 3')
+    dut.expect('Test 4')
+
+
+@pytest.mark.generic
+@idf_parametrize('target', ['esp32'], indirect=['target'])
+def test_unit_test_order(dut: Dut) -> None:
+    verify_test_order(dut)
+
+
+@pytest.mark.host_test
+@idf_parametrize('target', ['linux'], indirect=['target'])
+def test_unit_test_order_linux(dut: Dut) -> None:
+    verify_test_order(dut)

components/unity/test_apps/sdkconfig.defaults

@@ -0,0 +1,2 @@
+CONFIG_ESP_TASK_WDT_EN=n
+CONFIG_UNITY_TEST_ORDER_BY_FILE_PATH_AND_LINE=y

components/unity/unity_runner.c

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2016-2022 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2016-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -11,6 +11,7 @@
 #include <stdio.h>
 #include "unity.h"
 #include "esp_system.h"
+#include "sdkconfig.h"
 
 /* similar to UNITY_PRINT_EOL */
 #define UNITY_PRINT_TAB() UNITY_OUTPUT_CHAR('\t')
@@ -24,11 +25,37 @@ void unity_testcase_register(test_desc_t *desc)
     if (!s_unity_tests_first) {
         s_unity_tests_first = desc;
         s_unity_tests_last = desc;
-    } else {
-        test_desc_t *temp = s_unity_tests_first;
-        s_unity_tests_first = desc;
-        s_unity_tests_first->next = temp;
+        return;
     }
+#if CONFIG_UNITY_TEST_ORDER_BY_FILE_PATH_AND_LINE
+    test_desc_t *prev = NULL;
+    test_desc_t *current = s_unity_tests_first;
+
+    while (current) {
+        int file_cmp = strcmp(desc->file, current->file);
+        if (file_cmp < 0 || (file_cmp == 0 && desc->line < current->line)) {
+            // Insert before current
+            if (prev) {
+                prev->next = desc;
+            } else {
+                // Inserting at the head
+                s_unity_tests_first = desc;
+            }
+            desc->next = current;
+            return;
+        }
+        prev = current;
+        current = current->next;
+    }
+
+    // Insert at the end
+    prev->next = desc;
+    s_unity_tests_last = desc;
+#else
+    // Insert at head (original behavior)
+    desc->next = s_unity_tests_first;
+    s_unity_tests_first = desc;
+#endif
 }
 
 /* print the multiple function case name and its sub-menu