Refactored 'length(stack)' and added test.

lib/stack.c

@@ -45,15 +45,13 @@ bool empty(struct stack *stack) {
 }
 
 int length(struct stack *stack) {
-  struct stack *iterator = stack;
+  int length;
-  int length = 0;
 
   if (!empty(stack)) {
-    length = 1;
+    for (length = 1; stack->next; stack = stack->next, length++)
-    while (iterator->next != NULL) {
+      ;
-      length++;
+  } else {
-      iterator = iterator->next;
+    length = 0;
-    }
   }
 
   return(length);

test/stack_test.c

@@ -47,6 +47,28 @@ void test_empty_on_non_empty_stack() {
   return;
 }
 
+void test_length() {
+  struct stack *stack;
+  struct card *card[4];
+
+  allocate_stack(&stack);
+  initialize_stack(stack);
+
+  assert(length(stack) == 0);
+
+  for (int i = 0; i < 4; i++) {
+    allocate_card(&card[i]);
+    initialize_card(card[i]);
+    set_card(card[i], i, SPADES, EXPOSED, 0, 0);
+    push(&stack, card[i]);
+    assert(length(stack) == i + 1);
+  }
+
+  free_stack(stack);
+
+  return;
+}
+
 void test_push_on_empty_stack() {
   struct stack *stack;
   struct card *card;
@@ -199,6 +221,8 @@ void test_stack() {
   test_empty_on_empty_stack();
   test_empty_on_non_empty_stack();
 
+  test_length();
+
   test_push_on_empty_stack();
   test_push_on_non_empty_stack();
   test_push_null_on_empty_stack();