Worksheet: J1

Worksheets are self-guided activities that reinforce lectures. They are due Thursdays the week they are assigned.

Please submit your answers to the questions as comments in a J1.md markdown file you’ll be writing in this lab. To render your file, create a github repo and upload your file there – it can be viewed in your web browser.

Grading rubric and submission

When you are done, submit your J1.md file as well as your tests.txt file to BB.

You will be graded on the following:

Questions

1. What is fault localization? Provide your answer using at least one bolded phrase using markdown.

   Reveal Solution

   Fault localization typically involves tracing back from the line of code producing the incorrect output to where the problem actually was. To do this, a failing test case is needed, as well as the ability to trace through code, whether with print statements or a debugger.

2. What are three benefits of Test Driven Development (TDD)? Provide your answer using an unordered list in markdown.

   Reveal Solution

   • Your tests are not biased by your code
   • Writing tests helps you think about how you might write code
   • Writing tests helps you think about the requirements of your system

3. Given the example of requirements for generating a password:

   • It must have at least one number.
   • It must have at least one uppercase letter.
   • It must have at least one lowercase letter.
   • It must not contain the website gmail anywhere. (For example if we were generating a password for gmail accounts)
   • It can only be made up of letters, numbers, and the underscore.

   What are the input domain paritions for this exercise? Provide your answer using an unordered nested lists in markdown.

   Reveal Solution

   First, we have valid and invalid passwords:

   • invalid
   • valid

   But each of these groups can be refined as:

   • invalid
   • • missing uppercase letter
   • • missing lowercase letter
   • • missing number
   • • missing all combinations of the three items above
   • • contains gmail
   • • contains non-valid characters
   • valid

   Although the question did not ask for this, more tests could/should be generated by looking at the edge cases between these partitions.

4. Complete the truth table below to show what inputs we need to achieve active clause coverage for the following conditional:

   if ( ( (a > b) or G ) and (x < y) )
   

   a > b

   G

   x < y

   predicate outcome

   clause responsible

   Google how to make a table in markdown, and use a table to represent your results, like we did in class.

   Reveal Solution

   a > b	G	x < y	predicate outcome	clause responsible
   T	T	T	T	x < y
   T	T	F	F	x < y
   F	T	T	T	G
   F	F	T	F	G
   T	F	T	T	a > b
   F	F	T	F	a > b

5. Consider the control flow graph below. What are all the paths (using node numbers) that would achieve full path coverage as a test criteria? Is this a finite set?

   When listing all the paths, style your answer so that it appears like code (a code-like font with a gray background).

   

   Reveal Solution

   The set is infinite because of the loop between 3 and 4:

   `
   12567
   1257
   13567
   1357
   1343567
   134357
   13434567
   1343457
   134..567
   134..67
   `

6. What benefit does mutation testing offer over other testing methods discussed in class? Use a link in markdown to link to the definition of mutation testing we have in our lecture notes from today.

   Reveal Solution

   Mutation testing is automated, in the sense that it solves the oracle problem: there is no need to define expected outputs, because we assume the current functionality of the program under test is correct (and therefore the correct output). Our goal is not to test the correctness of this code directly, but to test how complete/effective our test suite is. The assumption is that real bugs will be found in the code if we generate a robust enough test suite.

7. Finish the in-class exercise for finding the fault in the checkCode method.

   Reveal Solution

   Solution omitted.