Add more tests for cyphalHeaderCrcAdd()

Author: hungatamazon

tests/test_private_crc.cpp

@@ -26,8 +26,28 @@ TEST_CASE("CyphalHeaderCRC")
 {
     using exposed::cyphalHeaderCrcAdd;
 
+    // Standard Cyphal header size = 24. The last 2 bytes are for the CRC.
+
+    // Standard use case. Header size = 24; CRC is calculated from the first 22 bytes.
+    // The last two bytes (CRC) are ignored in the calculation.
     std::uint16_t crc = 0xFFFFU;
     const uint8_t* header = reinterpret_cast<const uint8_t*>("\x01\x02\x03\x04\x05\x06\x07\x08\x09\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x20\x21\x22\x23\x24");
     crc = cyphalHeaderCrcAdd(crc, 22, header);
     REQUIRE(0xB731 == crc);
+
+    // Verify CRC when the size field is equal to the size of the header.
+    crc = 0xFFFFU;
+    header = reinterpret_cast<const uint8_t*>("\x01\x02\x03\x04\x05\x06\x07\x08\x09\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x20\x21\x22");
+    crc = cyphalHeaderCrcAdd(crc, 22, header);
+    REQUIRE(0xB731 == crc);
+    crc = 0xFFFFU;
+    header = reinterpret_cast<const uint8_t*>("\x01\x02\x03\x04\x05\x06\x07\x08\x09\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x20\x21\x22\x23\x24");
+    crc = cyphalHeaderCrcAdd(crc, 24, header);
+    REQUIRE(0x96BB == crc);
+
+    // Verify CRC when the size field is less than the size of the header. Extra data is ignored.
+    crc = 0xFFFFU;
+    header = reinterpret_cast<const uint8_t*>("\x01\x02\x03\x04\x05\x06\x07\x08\x09\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x20\x21\x22\x23\x24");
+    crc = cyphalHeaderCrcAdd(crc, 10, header);
+    REQUIRE(0x9F09 == crc);
 }