How to do Test Driven Development with AWS Lambda Function in Python
How to do Test Driven Development with AWS Lambda Function in Python
This episode shows how to write an AWS Lambda Function in Python following the TDD (Test Driven Development) approach. This leverages on boto3 python module to allow calls to AWS API and moto to mock the calls to AWS Services.
Github Link: https://github.com/dyordsabuzo/pablos…
#Python #TDD #AWSLambdaFunction
Content
0.4 -> hello welcome to public spot i'm george today i'll
be doing something different i will show you how
6.72 -> i write a lambda function using tdd approach
or test driven development let's start coding
21.84 -> so what i will try to achieve today is
to write an aws lambda function that will
27.04 -> generate new access keys
for a user i have installed
30.48 -> python pip and virtual and on my machine to do
my development work and the two primary python
37.28 -> modules that i will be using include photo 3 which
allows adbris calls in the background and moto
43.6 -> which is essentially a way for me to mock calls to
aws so i'll start by creating a space for my code
52.16 -> and then inside the lambda directory i will set up
my python virtual environment and then call it dev
60.32 -> i'll activate my virtual environment
64.24 -> now inside the lambda directory i will create
two requirements the text file one for the main
69.76 -> modules and then another one for my modules that
i need for testing and then in my requirements
76.24 -> the text i'll add boto3 and then on my
requirements test the text i'll add moto
82.4 -> pi test and pi yamu i'll go ahead and install
my modules inside my virtual environment
93.6 -> now that all my python modules are installed
i'll start creating a directory inside
97.84 -> lambda called app and then inside my app
directory i'll start creating my test file
112.88 -> i will start with the simplest test case so this
assertion actually failed because we have a space
132.32 -> in there so let's fix that save that and then run
our test again now we've got a first successful
140.16 -> test let's go ahead and move on to the next test
case so what if i allow the parameter access and
146.24 -> secret values to be provided by the caller
so i would create a new test case for this
162.56 -> save my changes and run my tests again
and then we have failed tests let's just
168.16 -> have a look it says it takes three positional
arguments but five were given so let's fix that
181.68 -> save changes and then run our test again
so again all my test cases are successful
188.48 -> so now i need to set a test case that will
test the actual creation of the access key
217.28 -> save our changes on our test.py
and then run our test again
223.36 -> so mock iam is not defined so let's fix that
228.56 -> save our changes run our test again
232.72 -> we have another error boto3
is not defined let's fix that
240.96 -> so as expected my test case failed it's looking
for the implementation of that new method and
246.72 -> if we look at our test case it's actually
expecting values to be populated in my
251.36 -> ssm so what i need to do is implement the part
where it populates my parameter store inside ssm
279.2 -> now that we've fixed the
implementation let's save our changes
282.64 -> and then run our test again so far all my
test cases have passed so now i need to
288.64 -> make sure that my parameter values are not
empty let me implement a test case for it
317.2 -> save my changes and run my tests again as expected
our test case failed because our assertions are
324.48 -> not satisfied so let's go ahead and fix that test
case save our changes then run our tests again
343.04 -> so now i need to create a new test case for a user
that doesn't exist before i start implementing the
348.8 -> test case for handling users it doesn't exist i
need to import the module that i need to handle
354.56 -> the exceptions and that module is both core so i
need to go all the way to the top of my test.py
364 -> save that and then i can
start creating my test case
374.48 -> save my changes and run my test again
378.96 -> my test case ran successfully which means we
do not have to implement anything to handle
383.04 -> the exception what i've written so far
is capable of handling situations where
387.84 -> user that does not exist so we are
good now on to the next test case
392.24 -> aws imposes limit of two axis kits per
im so i will create a test case for this
424.88 -> save my changes and run our test
430.32 -> as expected the test case failed and the
assertions are not satisfied the way to fix this
436 -> is that i have to implement a way of deleting
old access keys before creating a new one
462 -> save our changes open terminal clear this and then
run our test again my test case failed because of
470.48 -> an incorrect assertion that i used at line 89
instead of a third equal this should be assert
476.56 -> true save that and then run my test again and now
all my six test cases are successful and my final
484.88 -> set of test cases are for the handler method
of my lambda function so let me write that up
506.56 -> save my tested py and then run my test again
510.96 -> as expected the test case failed
so let's go ahead and fix it
532.72 -> all seven test cases that i have set up are run
successfully and so the last bit that i want to
539.52 -> set up as a test case is exceptions when
calling handler so let me add that test case
555.36 -> run our test so all eight test cases that i've
written have ran and completed successfully so
562.56 -> at this point i have completed writing my
lambda function code that will generate
567.2 -> new access keys for users and if you've
been working with aws you'd know that one
573.04 -> of the items in aws well architected framework is
ensuring that all access keys for iam users are
580.64 -> rotated regularly so this lambda function
will come in very handy anyways let's edit
587.2 -> in there and on the next episode i will
show you how i create a docker image and
592.8 -> set up this lambda function infrastructure that
would use this docker image so that's it for now
599.44 -> let me know what you think on the comments
below send me some likes or share this video
603.44 -> if you find it useful and subscribe
to this channel until next time see ya
Source: https://www.youtube.com/watch?v=KBr7yKXI-G4