1 files changed, 55 insertions, 0 deletions

diff --git a/firmware/test/rtt_test.c b/firmware/test/rtt_test.c
new file mode 100644
index 0000000..cdedabd
--- /dev/null
+++ b/firmware/test/rtt_test.c
@@ -0,0 +1,55 @@
+#include <stdint.h>
+#include <unity.h>
+
+#define SENT_TIME_1_MS 1000
+#define NOW_TIME_1_MS 1500
+#define RTT_POSITIVE_EXPECTED 500
+
+#define SENT_TIME_2_MS 2000
+#define NOW_TIME_2_MS 2000
+#define RTT_ZERO_EXPECTED 0
+
+#define SENT_TIME_3_MS 3000
+#define NOW_TIME_3_MS 2500
+#define RTT_NEGATIVE_EXPECTED (-500)
+
+/*
+ * calculate_rtt - calculate round-trip time
+ * @sent_ms: time when message was sent (ms)
+ * @now_ms: current time (ms)
+ *
+ * Return: RTT in milliseconds (now_ms - sent_ms)
+ */
+static int32_t calculate_rtt(int32_t sent_ms, int32_t now_ms)
+{
+        return now_ms - sent_ms;
+}
+
+static void test_rtt_positive_difference(void)
+{
+        TEST_ASSERT_EQUAL_INT32(RTT_POSITIVE_EXPECTED,
+                                calculate_rtt(SENT_TIME_1_MS, NOW_TIME_1_MS));
+}
+
+static void test_rtt_zero_difference(void)
+{
+        TEST_ASSERT_EQUAL_INT32(RTT_ZERO_EXPECTED,
+                                calculate_rtt(SENT_TIME_2_MS, NOW_TIME_2_MS));
+}
+
+static void test_rtt_negative_difference(void)
+{
+        TEST_ASSERT_EQUAL_INT32(RTT_NEGATIVE_EXPECTED,
+                                calculate_rtt(SENT_TIME_3_MS, NOW_TIME_3_MS));
+}
+
+int app_main(void)
+{
+        UNITY_BEGIN();
+
+        RUN_TEST(test_rtt_positive_difference);
+        RUN_TEST(test_rtt_zero_difference);
+        RUN_TEST(test_rtt_negative_difference);
+
+        return UNITY_END();
+}