tests/: Assert on NULL heap allocations in tests

Change-Id: Id2adcfe859fb25d2a7f0734655c6b9a58c0890b6
Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/71919
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>

tests/helpers.c

@@ -45,6 +45,7 @@ void strcat_realloc_test_success(void **state)
 	const char src0[] = "hello";
 	const char src1[] = " world";
 	char *dest = calloc(1, 1);
+	assert_non_null(dest);
 	dest = strcat_realloc(dest, src0);
 	dest = strcat_realloc(dest, src1);
 	assert_string_equal("hello world", dest);