CSE15L Lab Report 2 (Week 4)

This blog post is written as Lab Report 2 for CSE15L. Here, I will discuss three code changes my lab partner and I made while debugging our code in our Week 3 Lab.

Code Change 1: Characters After Final Close Parenthesis

Code Change Diff From Github

Code Diff 1

Failure-Inducing Test File

Link to the test file which caused the bug

Symptom of Failure-Inducing Input

Symptom 1

Relationship Between the Bug, Symptom, and Failure-Inducing Input

The test file was a failure-inducing input because it contained a space after the final parenthesis of the last link. Since the space is counted as a character, it increases the length of the test file. The code relies on a while loop to break; however, the break condition cannot be satisfied because currentIndex can never be greater than or equal to mardown.length if the final close parenthesis is not the final character of the file. As a result, running the file produces an infinite loop and results in an OutofMemoryError error.

Code Change 2: Missing Parenthesis

Code Change Diff From Github

Code Diff 2

Failure-Inducing Test File

Link to the test file which caused the bug

Symptom of Failure-Inducing Input

Symptom 2

Relationship Between the Bug, Symptom, and Failure-Inducing Input

The test file was a failure-inducing input because it contained missing parenthesis. The code relies on the presence of both open and close parenthesis to be able to determine where the links start and end and what the contents within the parenthesis are. When running the code with the failure-inducing input, the index of the parenthesis are set to -1 since they are not present, which results in an IndexOutOfBoundsException error because -1 is not a valid index.

Code Change 3: Missing Brackets

Code Change Diff From Github

Code Diff 3

Failure-Inducing Test File

Link to the test file which caused the bug

Symptom of Failure-Inducing Input

Symptom 3

Relationship Between the Bug, Symptom, and Failure-Inducing Input

The test file was a failure-inducing input because it was missing the close brackets for the link. Although the initial change fixed the edge case of a missing open bracket, a missing close bracket still broke the code because the value of currentIndex relied on an invalid closeBracket value of -1. The invalid closeBracket value meant that once again, the while loop condition while(currentIndex < markdown.length()) could never be satisfied, resulting in an infinite while loop.

End

Thank you for reading!