Test Case for Sorted Singl Linked List

Write test case(s) and explanation the same for below program.
(1) Assume two sorted singly link lists. Merge them into a one sorted singly link list.
struct Node{
int data;
Node* next
};
Implement,
Node* SortedList(Node* list1, Node* list2);

(2) Write test cases for following function, mention your assumption(s) if any:
BOOL CopyFiletoString(FILE *hfile, char *str, size filesize);
calling the function like following:
vbool = CopyFiletoString (hfile, str, 100);