7. Testing, Debugging, Exceptions, and Assertions

MIT 6.0001 Introduction to Computer Science and Programming in Python, Fall 2016
View the complete course: ocw.mit.edu/6-0001F16
Instructor: Dr. Ana Bell
In this lecture, Dr. Bell discusses testing, debugging, and exceptions and assertion statements in Python.
License: Creative Commons BY-NC-SA
More information at ocw.mit.edu/terms
More courses at ocw.mit.edu

[@leixun]

*My takeaways:* 1. Defensive programming: testing/validation and debugging 4:20 2. Three classes of test: unit testing, regression testing and integration testing 6:25 3. Testing approaches: natural boundaries for numbers, random testing, black box testing and glass box testing 7:45 4. Black box testing is based on specification, an example 9:05 5. Glass box testing tries to test every single path of the code 10:20 6. Using the print statement to debug 15:17 7. General debugging steps 17:20 8. How to debug logic errors 18:42, try rubber ducky debugging 9. Do and Don't 20:00 10. Exceptions 21:40 11. Assertions 37:45

[@muneebqureshi8862]

Good work.

[@Amy_Yu2023]

Lei Xun Thanks for sharing

[@steverobinson8771]

Thank you for taking the time over your reply

[@MaeLSTRoM1997]

If bug fell in the soup, just eat it

[@denisecarillo2586]

She's really easy to learn from. Thank you for teaching and positing this online without charge

[@willcheung7041]

and she is hot

[@jcavs9847]

@@willcheung7041 feels weird man

[@88Oleksiy]

@@willcheung7041 very inappropriate

[@EZ-hc5sh]

Don’t care. Before I go, why did you volunteer that info? Unless she requested said statement be relayed, who youis, P? Either way, is a quick way to farm out, there..uum, P. Or p, really, cuz u ain’t proper- or correct. correctional yes, attitude-oh yard time gotta go fill my cup one drop at a time

[@Saganist420]

"Decide it's high protein and declare it a feature". That's hilarious. ahahah

[@yukeyang5735]

I guess the soup would be tasty.That guy is funny.Haha.

[@serkansenturk6945]

The Elder Scrolls V: Skyrim likes this

[@juanperezmondragon1676]

that's actually what we do in mexico, grasshoppers are a traditional snack in some parts of the country, cus in the prehispanic times the solution to famines due to plagues was eating the insect that caused them.

[@dhruv_aditya]

Dr. Anna Bell is a great instructor, Thank you MIT OCW for making this high quality content online absolutely for free.

[@rooneymara8061]

Amazing how she gets better as the lectures go on

[@JamBear]

Just like coding

[@mohammadsamir2713]

although i am not a native or the best in english , i can hear every word and understand her i want to thank you a lot Dr. Ana

[@davidorsa4406]

Dr.Hanna, you are awesome instructor and you made learning fun. Thank you very much!!!!

[@nancylu4049]

Dr. Ana Bell is a great instructor!

[@user-fl7vs4ed6l]

pre labeling ​​0:01:02 We aim for high quality - an analogy with soup 0:02:00​ 0:03:46 Programming so far 0:06:48 Classes of test 0:08:02 Testing approaches 0:10:00 Glass box testing ​0:11:02 ​0:11:48 ​0:14:00​ 0:16:00 0:17:26 Debugging steps 0:19:33 0:20:05 Don't and Do ​0:22:16 Other types of exception 0:24:08 ​ 0:25:41 Handling specific exception 0:27:09​ Other exception 0:28:15 What to do with exception 0:31:15 ​Example : Raising an exception 0:32:00 0:33:52 ​ 0:35:31 ​Option 1 0:37:01​ Option 2 0:38:38 Example 0:40:48 Where to use assertion

[@PradeepKumar-gq8ej]

Love this session, fund very easy and clear and fun. Thank you so much for sharing..

[@IACOIACOIACO]

this lecture was a godsend, feeling a lot more eager and motivated to learn programming, especially when there are tools at your disposal when shit hits the fan !!

[@TheMinaProject]

Watched so many videos but only Dr Ana Bell's one stuck! Thank you!

[@DistortedV12]

Where was this video when I started learning programming, would've saved me a lot of time

[@Lexaire]

26:35 for the last case, it will raise an Exception on interrupts like KeyboardInterrupt when you press CTRL+C. Programmers should be careful having broad except cases. If you had an infinite loop that caught all exceptions it would be hard to kill the program.

[@jiakai7254]

perhaps the most valuable lecture in this series

[@nephetssnephetss1508]

Dr. Anna Bell. This is great.

[@bla3029]

Your voice and words are very clear good for concentration

[@antoniobuccoliero5437]

Bravissima, complimenti!!!

[@akbarrauf2741]

thank you ,mit

[@jaddadzakaria]

love these lectures

[@jesuelmarques2241]

At 26:42 she says that she couldn't think of an error that would be raised besides these two. I thought of one: if a/b is too large, Python won't be able to represent it as a float and would raise an OverflowError

[@oussematoussli8085]

this proffesor is really great i wish i could study for her

[@hectort88]

We use the "rubber ducking" method, not for coding but for general problem solving in our IT department with an empty pringles can.

[@oximas-oe9vf]

I talk to my tulpa (a consious imaginary friend) LOL

[@jojojojo4862]

You are the best👏🏻👏🏻❤️ thanks Professor Anna

[@jmjtoob]

"Decide it's high protein and declare it a feature"... I may have worked as a software engineer for that student's father in the past.

[@hektor6766]

I think he has many fathers.

[@sarthakraj3981]

Pretty sure that was John, and not a student

[@alexandrugheorghe5610]

26:43 one more exception can be KeyboardInterrupt

[@aviliocarcamo6454]

Does anyone know in which video she talks about the Rubber Ducky?

[@aymensekhri2133]

thanks a lot

[@sha11e]

These are great, and Ana is great. Was worried when there was a new teacher in the last video.

[@adas21]

Mr. Eric Grimmson is actually better and more experienced

[@oximas-oe9vf]

@@adas21 yaa but prof. Ana is more fun and has more jokes

[@geekyprogrammer4831]

@@oximas-oe9vf we are here to learn not for jokes

[@oximas-oe9vf]

@@geekyprogrammer4831 welll jokes secrete happy hormones inside you which generate emotion and emotions help with memory and help you get motivated to learn more

[@HexagonalColumbus]

36:21 How did you divide 100 by 3 and got 15.41666? Same for other lines. You should debug your code

[@sheikhakbar2067]

Could debugging be fun; I hope so!

[@obli8984]

thanks she is back after him

[@jpdroidjp]

Lecturer is very good, it's not easy teaching programming. But for some reason I'm hung up on her pacing back and forth, and I can't get it out of my head! I wish I never thought of it now.

[@Tintak_hatpin]

I am surprised that no one in the class asked why does it raise ValueError instead of TypeError, as the user provides the wrong Type of input i.e string Type whereas the expected input was integer Type. I had to google to find the answer. May be they already know the answer ?

[@anlbasaran8206]

even though the user provides a string , n = int(input("How old are you? ")) this line converts n to an integer, even though n = twenty , which doesnt sount like an integer but when you ask type() it will return the answer "integer" so the error isnt a type error, sorry for the messy explaination even if you already googled and learned the answer , it might help the people who hasnt :D

[@Tarun-zf5ep]

CD Projekt Red should watch this.

[@dve845]

be conservative in what you output and liberal in accepting your input? ... exceptions demand catches, just as return values rquire if's

[@JeetSingh-kp5xq]

what is need of raising the exception? we can simply use print statement and break ?

[@adrianivanov6626]

How do I do the thing where she selects multiple lines of code and adds a # in front of each of them at once?

[@jasonchen0429]

Select the code then press ctrl+1

[@adrianivanov6626]

Jason Chen Thanks

[@quintonconoly]

@@jasonchen0429 Thanks

[@iansullivan9738]

Current American model for dealing with the first analogy: Burn the ceiling down

[@Mark-wq7wd]

Your brain is the kitchen. Keep that place clean and sharp

[@evanmcarthur478]

The first answer was genius, she laughs, but thats what companies do all the time release buggy software .....then endless patches.

[@yodgoralisherov289]

👍👍👍

[@TedsWorld101]

Anyone: Did you learn anything today? Me: Yeah, talking to rubber duckies helps me with my problems.

[@JeffBarron1]

stand still damn it!

[@bimboblacky]

COVERED soup only prevents *more* bugs from invading. Complete cleaning of the house means deleting all applications, removing the entire operating system, & then low-level formatting everything! *yeah* baby *yeah*

[@xmnemonic]

she has BLE: big lecture energy

[@mindywashere]

i still havent found out how to get all the #(comments) away like shes does. she highlights a block and does something that gets them to all be not commented then

[@windzhang6708]

select all the #(comments), then press ctrl + 1. It is working in the spyder.

[@mindywashere]

thanks, i thought it was something simple like that but that doesnt work in pyscripter :/

[@mihirpatel8216]

try doing Ctrl-/ or Ctlr/#

[@ReverendRichardSeeland568209]

@hammertapping But then you have to install Numpy and PySci manually.

[@gehanameresekere1345]

Python IDLE has this feature comment section or uncomment section.

[@varungupta5493]

is there a way to know which pset to do after which lecture?

[@mitocw]

At the bottom of the Syllabus page on the full course site on OCW ocw.mit.edu/6-0001F16 there is a Calendar with the release and due dates of the psets. Good luck with your studies!

[@varungupta5493]

@@mitocw Thanks!

[@PhilippeCarphin]

Don't backup your code, make a commit with git

[@PhilippeCarphin]

That's a bit much for people who are learning about if statements. All they need is version control. The advice she was giving was one of version control even though she used the word backup. But if you're going to do a backup, wouldn't it be better to backup your repo by having a remote repository whose url is a path to some place on another drive.

[@sandeepkosta5750]

these days ide does that for us.. making our life a lot easier

[@McAwesomeReaper]

I feel like 85% of the engineers I work with skipped this class.

[@quocvu9847]

32:53

[@funandmotivationweekly]

comment the code what you have written and not working, so you don't endup doing the same implemenation again while doing the testing, cleanup at the end of finding the solution.

[@quocvu4023]

18:24

[@chrischungy]

19:33 Professor's kid is probably going start to dreaming in code and grow up to be a wizard.

[@pgoeds7420]

Try not to use ingredients with bugs already in.

[@Xgckl]

That program for the class wouldn't work. The first student in class_list would get a correct entry in new_stats but then in the next step of the for-loop his grades and the next student would go into new_stats. Also, the program would try to do avg on his name, so you would definitely get an error message.

[@hoangfuongduy]

no dude, she separated the avg function to debug, that means when insert in back to the main function, she will amend the argument to be the right argument. As earlier we know that to debug we will devide the main program to smallers functions and check indiviualy.

[@sharketespark6495]

Deadpool never comes to any tests😢

[@wanyinleung912]

Voice crack at 38:57

[@quintonconoly]

lol

[@germanarrowood2748]

The abundant look prenatally slow because test noteworthily tug barring a many confirmation. mammoth, hollow passive

[@sanjeetkumarrai4998]

disappoint beyond belief!!!

[@ramazanaktas3699]

I wish she had praticed a little before lectures. Maybe 1/5 of lectures goes with "ehm", "umm", "err" or an awkward silence.