Add specs for boundary cases

3 files changed, 107 insertions, 5 deletions

diff --git a/src/01/01b/README.md b/src/01/01b/README.md
index bc25dc6..4bf8070 100644
--- a/src/01/01b/README.md
+++ b/src/01/01b/README.md
@@ -10,6 +10,77 @@ Implement the stack methods `push(x)` and `pop()` using two queues.
 Analyze the running time of the `push(x)` and `pop()` operations based on this implementation.
 
 ## Description of the Code
+
+The `push()` function is used to push a new item to the top of the stack.
+The `pop()` function is used to pop the item off the top of the stack.
+
+The implementation of the `push()` function operates in linear time `O(n)`.
+The implementation of the `pop()` function operates in linear time `O(n)`.
+
 ## Errors and Warnings
+
+The design this program I used [cgreen](https://cgreen-devs.github.io/) to unit test the pseudo public
+functions of the Stack interface.
+
+The [`stack_test.c`](./stack_test.c) file includes unit tests to cover the following scenarios:
+
+* popping an item off of an empty stack
+* popping an item off of the stack
+* popping successive items off of the stack
+* pushing an item onto a full stack
+* pushing an item onto the stack
+
+```bash
+モ make run_test
+mkdir build
+clang    -c -o build/stack.o stack.c
+clang    -c -o build/stack_test.o stack_test.c
+clang build/stack.o build/stack_test.o -lcgreen -o build/test
+Running "main" (3 tests)...
+  "stack_tests": 5 passes in 1ms.
+Completed "main": 5 passes in 1ms.
+```
+
 ## Sample Input and Output
+
+```bash
+モ make run
+clang build/stack.o build/main.o -o build/program
+./build/program
+=== COMP-272 - Assignment 1 - Question 1b ===
+Push: 383
+Push: 886
+Push: 777
+Push: 915
+Push: 793
+Push: 335
+Push: 386
+Push: 492
+Push: 649
+Push: 421
+
+[383,886,777,915,793,335,386,492,649,421]
+Pop: 421
+[383,886,777,915,793,335,386,492,649]
+Pop: 649
+[383,886,777,915,793,335,386,492]
+Pop: 492
+[383,886,777,915,793,335,386]
+Pop: 386
+[383,886,777,915,793,335]
+Pop: 335
+[383,886,777,915,793]
+Pop: 793
+[383,886,777,915]
+Pop: 915
+[383,886,777]
+Pop: 777
+[383,886]
+Pop: 886
+[383]
+Pop: 383
+[]
+Bye
+```
+
 ## Discussion
diff --git a/src/01/01b/stack.c b/src/01/01b/stack.c
index 7fff245..dfe3c05 100644
--- a/src/01/01b/stack.c
+++ b/src/01/01b/stack.c
@@ -2,6 +2,8 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+static int MAX_SIZE = 2147483647;
+
 /**
  * Constructs a new instance of a queue
  *
@@ -83,7 +85,8 @@ int dequeue(Queue *self) {
  * @param data The data to push on to the stack
  */
 void push(Stack *self, int data) {
-  enqueue(self->q1, data);
+  if (self->q1->size < MAX_SIZE)
+    enqueue(self->q1, data);
 }
 
 /**
@@ -93,10 +96,14 @@ void push(Stack *self, int data) {
  * @return The data associated with the item to pop off the stack
  */
 int pop(Stack *self) {
-  int count = self->q1->size - 1;
+  int count = self->q1->size;
+
+  if (count <= 0)
+    return 0;
+
   Queue *tmp = newQueue();
 
-  for (int i = 0; i < count; i++)
+  for (int i = 0; i < count - 1; i++)
     enqueue(tmp, dequeue(self->q1));
 
   int data = dequeue(self->q1);
diff --git a/src/01/01b/stack_test.c b/src/01/01b/stack_test.c
index 457f656..b05f278 100644
--- a/src/01/01b/stack_test.c
+++ b/src/01/01b/stack_test.c
@@ -1,5 +1,6 @@
-#include <cgreen/cgreen.h>
 #include "stack.h"
+#include <cgreen/cgreen.h>
+#include <math.h>
 
 Describe(Stack);
 BeforeEach(Stack){ }
@@ -38,12 +39,35 @@ Ensure(Stack, pop_successive_items) {
   destroy(stack);
 }
 
+Ensure(Stack, when_popping_an_item_off_an_empty_stack) {
+  Stack *stack = initialize();
+
+  assert_that(pop(stack), is_equal_to(NULL));
+
+  destroy(stack);
+}
+
+Ensure(Stack, when_pushing_an_item_on_to_a_full_stack) {
+  Stack *stack = initialize();
+  int max = 2147483647;
+
+  for (int i = 0; i < max; i++)
+    push(stack, 1);
+
+  push(stack, 1);
+
+  assert_that(size(stack), is_equal_to(max));
+  destroy(stack);
+}
+
 TestSuite *stack_tests() {
   TestSuite *suite = create_test_suite();
 
-  add_test_with_context(suite, Stack, push_onto_stack);
   add_test_with_context(suite, Stack, pop_single_item);
   add_test_with_context(suite, Stack, pop_successive_items);
+  add_test_with_context(suite, Stack, push_onto_stack);
+  add_test_with_context(suite, Stack, when_popping_an_item_off_an_empty_stack);
+  add_test_with_context(suite, Stack, when_pushing_an_item_on_to_a_full_stack);
 
   return suite;
 }