tests/unittests: Add tests for endian.h

tests/unittests/tests-libc/tests-libc.c

@@ -8,6 +8,7 @@
 
 #include <stdint.h>
 #include <string.h>
+#include <endian.h>
 #include "string_utils.h"
 
 #include "tests-libc.h"
@@ -39,11 +40,44 @@ static void test_libc_memchk(void)
     TEST_ASSERT(memchk(buffer, 0xff, sizeof(buffer)) == &buffer[5]);
 }
 
+union u16 {
+    uint8_t as_bytes[2];
+    uint16_t as_number;
+};
+
+union u32 {
+    uint8_t as_bytes[4];
+    uint32_t as_number;
+};
+
+union u64 {
+    uint8_t as_bytes[8];
+    uint64_t as_number;
+};
+
+static void test_libc_endian(void)
+{
+    const union u16 u16_be_expected = { .as_bytes = { 0x01, 0x02 } };
+    const union u16 u16_le_expected = { .as_bytes = { 0x02, 0x01 } };
+    const union u32 u32_be_expected = { .as_bytes = { 0x01, 0x02, 0x03, 0x04 } };
+    const union u32 u32_le_expected = { .as_bytes = { 0x04, 0x03, 0x02, 0x01 } };
+    const union u64 u64_be_expected = { .as_bytes = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 } };
+    const union u64 u64_le_expected = { .as_bytes = { 0x08, 0x07, 0x06, 0x05, 0x04, 0x03, 0x02, 0x01 } };
+
+    TEST_ASSERT_EQUAL_INT(htobe16(0x0102), u16_be_expected.as_number);
+    TEST_ASSERT_EQUAL_INT(htole16(0x0102), u16_le_expected.as_number);
+    TEST_ASSERT_EQUAL_INT(htobe32(0x01020304), u32_be_expected.as_number);
+    TEST_ASSERT_EQUAL_INT(htole32(0x01020304), u32_le_expected.as_number);
+    TEST_ASSERT_EQUAL_INT(htobe64(0x0102030405060708), u64_be_expected.as_number);
+    TEST_ASSERT_EQUAL_INT(htole64(0x0102030405060708), u64_le_expected.as_number);
+}
+
 Test *tests_libc_tests(void)
 {
     EMB_UNIT_TESTFIXTURES(fixtures) {
         new_TestFixture(test_libc_strscpy),
         new_TestFixture(test_libc_memchk),
+        new_TestFixture(test_libc_endian),
     };
 
     EMB_UNIT_TESTCALLER(libc_tests, NULL, NULL, fixtures);