Design by Contract

Question 1

What is design by contract

Answer 1

defining interface specifications for software modules (e.g. functions). It specifies what the module expects and what it promises to deliver, what it maintains

Question 2

What are the elements of design by contract?

Answer 2

1. Pre-condition: What you assume to be true before running the module
2. Post-conidition: What you assume to be true after running the module
3. Some well-defined properties that should always be true about the stat of our program

Question 3

What are assertions?

Answer 3

A software bug arises often because your assumptions are wrong. So it is useful to enforce your assumptions as executable code. That way, as soon as they get violated, you immediately know.

Meant for developers (not user friendly)

Question 4

How do you compile without assertions

Answer 4

clang -Wall -DNDEBUG

Question 5

How do you assert a large block of code?

Answer 5

Turn it into a function:

Question 6

Defensive Programming:

How do you check an error return?

Answer 6

Question 7

What cases should you test?

Answer 7

• typical cases
• edge cases
• special cases

Question 8

What is the difference between black and white box testing

Answer 8

Black - you do not see the code

White - you do see the code

Question 9

What is scaffolding?

Answer 9

Making our test into code, hard code the test data and the expected results and run it through your code.

Question 10

What are the general guidelines of testing?

Answer 10

1. Hard code test cases, results are verified automatically, not visually
2. keep test code simple
3. test paths and posibilities
4. a failed test is good (means you found and will fix a problem

Question 11

What is TDD

Answer 11

Test driven development

• write one simple test (that fails)
• write just enough code to pass that test
• add more test and repeat