test: add native Unity env with Utils tests

Adds an [env:native] for host-side unit tests (pio test -e native) with
a minimal Arduino.h stub, and covers the Utils helpers: _trim,
toBoolean, SETCHARPROP, sortArray and the Timestamp conversions.

The firmware envs now extend a shared [esp32] section instead of [env]
so the native env doesn't inherit the Arduino framework, the ESP32
libraries or the build scripts.

The half-hour calcTZOffset cases fail: +05:30 comes back as 2300.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

platformio.ini

@@ -12,9 +12,13 @@
 default_envs = esp32devdbg
 src_dir = src
 
-[env]
+; Shared by every firmware env (they extend it).  Kept out of [env] so the
+; native test env doesn't inherit the Arduino framework and ESP32 libraries.
+[esp32]
 platform =  espressif32 @ 6.13.0
 framework = arduino
+; Unit tests only run on the PC: pio test -e native
+test_ignore = *
 lib_deps = 
 	bblanchon/ArduinoJson@^7.2.2
 	lsatan/SmartRC-CC1101-Driver-Lib@^2.5.7
@@ -43,35 +47,40 @@ monitor_filters =
 ; task on core 1 (with loop()) never competes with network handling.
 [dualcore]
 build_flags =
-	${env.build_flags}
+	${esp32.build_flags}
 	-DCONFIG_ASYNC_TCP_RUNNING_CORE=0
 
 [env:esp32dev]
+extends = esp32
 board = esp32dev
 board_build.partitions = esp32_3MB.csv
 build_flags = ${dualcore.build_flags}
 
 [env:esp32devdbg]
+extends = esp32
 board = esp32dev
 build_type = debug
 board_build.partitions = esp32_3MB.csv
 build_flags = ${dualcore.build_flags}
 
 [env:esp32c3]
+extends = esp32
 board = esp32-c3-devkitm-1
 board_build.partitions = esp32_3MB.csv
 
 [env:esp32s3]
+extends = esp32
 board = esp32-s3-devkitc-1
 build_flags = ${dualcore.build_flags}
 
 [env:esp32c6]
+extends = esp32
 platform = https://github.com/pioarduino/platform-espressif32/releases/download/stable/platform-espressif32.zip
 board = seeed_xiao_esp32c6
 build_type = debug
 board_build.partitions = esp32_huge_app.csv
 build_flags =
-	${env.build_flags}
+	${esp32.build_flags}
 	-DCONFIG_FREERTOS_HZ=1000
 	-include "driver/gpio.h"
 lib_deps = 
@@ -86,3 +95,15 @@ lib_deps =
 	; High-level wrappers/servers
 	ESP32Async/ESPAsyncWebServer
 
+; Host-side unit tests: pio test -e native  (needs gcc/g++ on PATH).
+; Only the sources the tests cover are built; test/stubs stands in for Arduino.h.
+[env:native]
+platform = native
+test_framework = unity
+test_build_src = yes
+build_src_filter = -<*> +<Utils.cpp>
+build_flags =
+	-std=gnu++17
+	-Isrc
+	-Itest/stubs
+	-D_POSIX_THREAD_SAFE_FUNCTIONS

test/stubs/Arduino.h

@@ -0,0 +1,20 @@
+// Minimal stand-in for the Arduino core so firmware sources can be built for
+// the native test env (pio test -e native).  Only add what tested code uses.
+#ifndef arduino_stub_h
+#define arduino_stub_h
+#include <cctype>
+#include <cmath>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <ctime>
+
+// Fixed so anything formatted from it is deterministic.
+inline unsigned long millis() { return 0; }
+inline bool getLocalTime(struct tm *info, uint32_t ms = 5000) {
+  (void)ms;
+  time_t now = time(nullptr);
+  return localtime_r(&now, info) != nullptr;
+}
+#endif

test/test_utils/test_utils.cpp

@@ -0,0 +1,197 @@
+#include <unity.h>
+#include "Utils.h"
+
+// The C runtime only picks up TZ after it is re-read.
+static void setTZ(const char *tz) {
+#ifdef _WIN32
+  _putenv_s("TZ", tz);
+  _tzset();
+#else
+  setenv("TZ", tz, 1);
+  tzset();
+#endif
+}
+
+// 2024-03-05T07:08:09Z
+static const time_t SAMPLE_UTC = 1709622489;
+
+void setUp() { setTZ("UTC0"); }
+void tearDown() {}
+
+/*********************************************************************
+ * _trim
+ ********************************************************************/
+static void test_trim_strips_whitespace_and_quotes() {
+  char str[] = " \t\"Living Room\"\r\n";
+  _trim(str);
+  TEST_ASSERT_EQUAL_STRING("Living Room", str);
+}
+static void test_trim_keeps_clean_string() {
+  char str[] = "Kitchen";
+  _trim(str);
+  TEST_ASSERT_EQUAL_STRING("Kitchen", str);
+}
+static void test_trim_all_whitespace_becomes_empty() {
+  char str[] = " \t\r\n\" ";
+  _trim(str);
+  TEST_ASSERT_EQUAL_STRING("", str);
+}
+static void test_trim_empty_string() {
+  char str[] = "";
+  _trim(str);
+  TEST_ASSERT_EQUAL_STRING("", str);
+}
+
+/*********************************************************************
+ * toBoolean
+ ********************************************************************/
+static void test_toBoolean_missing_uses_default() {
+  TEST_ASSERT_TRUE(toBoolean(nullptr, true));
+  TEST_ASSERT_FALSE(toBoolean(nullptr, false));
+  TEST_ASSERT_TRUE(toBoolean("", true));
+  TEST_ASSERT_FALSE(toBoolean("", false));
+}
+static void test_toBoolean_true_values() {
+  TEST_ASSERT_TRUE(toBoolean("true", false));
+  TEST_ASSERT_TRUE(toBoolean("True", false));
+  TEST_ASSERT_TRUE(toBoolean("1", false));
+}
+static void test_toBoolean_false_values() {
+  TEST_ASSERT_FALSE(toBoolean("false", true));
+  TEST_ASSERT_FALSE(toBoolean("False", true));
+  TEST_ASSERT_FALSE(toBoolean("0", true));
+}
+static void test_toBoolean_unknown_uses_default() {
+  TEST_ASSERT_TRUE(toBoolean("yes", true));
+  TEST_ASSERT_FALSE(toBoolean("yes", false));
+}
+
+/*********************************************************************
+ * SETCHARPROP
+ ********************************************************************/
+static void test_setcharprop_copies_short_value() {
+  char prop[8];
+  SETCHARPROP(prop, "abc", sizeof(prop));
+  TEST_ASSERT_EQUAL_STRING("abc", prop);
+}
+static void test_setcharprop_truncates_long_value() {
+  char prop[5];
+  SETCHARPROP(prop, "abcdefgh", sizeof(prop));
+  TEST_ASSERT_EQUAL_STRING("abcd", prop);
+}
+
+/*********************************************************************
+ * sortArray / sortArrayReverse
+ ********************************************************************/
+static bool absLarger(int a, int b) { return abs(a) > abs(b); }
+
+static void test_sortArray_ascending() {
+  int arr[] = {5, -1, 3, 0, 3};
+  const int expected[] = {-1, 0, 3, 3, 5};
+  sortArray(arr, 5);
+  TEST_ASSERT_EQUAL_INT_ARRAY(expected, arr, 5);
+}
+static void test_sortArrayReverse_descending() {
+  int arr[] = {5, -1, 3, 0, 3};
+  const int expected[] = {5, 3, 3, 0, -1};
+  sortArrayReverse(arr, 5);
+  TEST_ASSERT_EQUAL_INT_ARRAY(expected, arr, 5);
+}
+static void test_sortArray_custom_comparator() {
+  int arr[] = {-4, 1, 3, -2};
+  const int expected[] = {1, -2, 3, -4};
+  sortArray(arr, 4, absLarger);
+  TEST_ASSERT_EQUAL_INT_ARRAY(expected, arr, 4);
+  const int reversed[] = {-4, 3, -2, 1};
+  sortArrayReverse(arr, 4, absLarger);
+  TEST_ASSERT_EQUAL_INT_ARRAY(reversed, arr, 4);
+}
+static void test_sortArray_empty_and_single() {
+  int one[] = {42};
+  sortArray(one, 1);
+  TEST_ASSERT_EQUAL_INT(42, one[0]);
+  int none[] = {7};
+  sortArray(none, 0);
+  TEST_ASSERT_EQUAL_INT(7, none[0]);
+}
+static void test_sortArray_moves_free_ids_last() {
+  // Free shade id slots are 255 and must end up after the used ones.
+  uint8_t ids[] = {3, 255, 1, 255, 2};
+  const uint8_t expected[] = {1, 2, 3, 255, 255};
+  sortArray<uint8_t>(ids, sizeof(ids));
+  TEST_ASSERT_EQUAL_UINT8_ARRAY(expected, ids, sizeof(ids));
+}
+
+/*********************************************************************
+ * Timestamp
+ ********************************************************************/
+static struct tm sampleTm() {
+  struct tm dt = {};
+  dt.tm_year = 2024 - 1900;
+  dt.tm_mon = 2;
+  dt.tm_mday = 5;
+  dt.tm_hour = 7;
+  dt.tm_min = 8;
+  dt.tm_sec = 9;
+  return dt;
+}
+static void test_formatISO_offsets() {
+  Timestamp ts;
+  struct tm dt = sampleTm();
+  TEST_ASSERT_EQUAL_STRING("2024-03-05T07:08:09.000+0000", ts.formatISO(&dt, 0));
+  TEST_ASSERT_EQUAL_STRING("2024-03-05T07:08:09.000-0500", ts.formatISO(&dt, -500));
+  TEST_ASSERT_EQUAL_STRING("2024-03-05T07:08:09.000+0530", ts.formatISO(&dt, 530));
+}
+static void test_calcTZOffset_whole_hours() {
+  time_t t = SAMPLE_UTC;
+  setTZ("UTC0");
+  TEST_ASSERT_EQUAL_INT(0, Timestamp::calcTZOffset(&t));
+  setTZ("EST5");
+  TEST_ASSERT_EQUAL_INT(-500, Timestamp::calcTZOffset(&t));
+}
+static void test_calcTZOffset_half_hour_east() {
+  time_t t = SAMPLE_UTC;
+  setTZ("IST-5:30");
+  TEST_ASSERT_EQUAL_INT(530, Timestamp::calcTZOffset(&t));
+}
+static void test_calcTZOffset_half_hour_west() {
+  time_t t = SAMPLE_UTC;
+  setTZ("NST3:30");
+  TEST_ASSERT_EQUAL_INT(-330, Timestamp::calcTZOffset(&t));
+}
+static void test_parseUTCTime_in_utc() {
+  setTZ("UTC0");
+  TEST_ASSERT_EQUAL_INT64((int64_t)SAMPLE_UTC, (int64_t)Timestamp::parseUTCTime("2024-03-05T07:08:09Z"));
+}
+static void test_parseUTCTime_ignores_local_zone() {
+  setTZ("IST-5:30");
+  TEST_ASSERT_EQUAL_INT64((int64_t)SAMPLE_UTC, (int64_t)Timestamp::parseUTCTime("2024-03-05T07:08:09Z"));
+}
+
+int main(int argc, char **argv) {
+  (void)argc;
+  (void)argv;
+  UNITY_BEGIN();
+  RUN_TEST(test_trim_strips_whitespace_and_quotes);
+  RUN_TEST(test_trim_keeps_clean_string);
+  RUN_TEST(test_trim_all_whitespace_becomes_empty);
+  RUN_TEST(test_trim_empty_string);
+  RUN_TEST(test_toBoolean_missing_uses_default);
+  RUN_TEST(test_toBoolean_true_values);
+  RUN_TEST(test_toBoolean_false_values);
+  RUN_TEST(test_toBoolean_unknown_uses_default);
+  RUN_TEST(test_setcharprop_copies_short_value);
+  RUN_TEST(test_setcharprop_truncates_long_value);
+  RUN_TEST(test_sortArray_ascending);
+  RUN_TEST(test_sortArrayReverse_descending);
+  RUN_TEST(test_sortArray_custom_comparator);
+  RUN_TEST(test_sortArray_empty_and_single);
+  RUN_TEST(test_sortArray_moves_free_ids_last);
+  RUN_TEST(test_formatISO_offsets);
+  RUN_TEST(test_calcTZOffset_whole_hours);
+  RUN_TEST(test_calcTZOffset_half_hour_east);
+  RUN_TEST(test_calcTZOffset_half_hour_west);
+  RUN_TEST(test_parseUTCTime_in_utc);
+  RUN_TEST(test_parseUTCTime_ignores_local_zone);
+  return UNITY_END();
+}