The clean code talks - unit testing

10/25/2015

Watch the google talk "The clean code talks - unit testing", write down notes and then learn better for next time.

  video link:
  https://www.youtube.com/watch?v=wEhu57pih5w

Video time:
02:02 / 32:07
Hard to test code

Most People say:
Make things private
Using final keyword
Long methods

Real issues:  (interview questions)
Mixing new with logic
Work in constructor
Global state
Singleton
Static Methods   (procedure programming) (leaf method vs way-up method)
Deep inheritance (Divorce myself from inheritance at run time. )
Too many conditionals ()


Procedure code - Seam - Polymorphism - Julia's comment: look into it, read more about it. 10/25/2015

Video time:
 14:35/32:07
Progression of Testing:

1. Scenario / Large Tests
  Test whole applicatio by prentending to be a user
  slow / Flaky / Mostly happy paths

2. Functional / Medium Tests
  External dependencies simulated
  Test class interaction

3. Unit / Small Tests
    Focus on application logic
    Very Fast / No I/O / No Need for a debugger

4. Think of it more as a continuum than discrete

5. All tests levels important
    Not all levels have the same probability of a bug
    Because smaller tests cover less need more of them

6. Testability more important as you get more focused

Video time:
17:05 /32:07
Different kinds of Tests
Execution time :
unit test -> Functional Tests -> Scenario

Test individual  ->
Test collections of classes as subsytems ->
Test the whole system pretending to be a user

Video time:
27:06/32:07
How do you write hard to test code?

You mix object creation code with business logic
This will assure that a test case never can construct a graph of objects different from production. Hence nothing can be tested in isolation.

Unit test class -
Seam - friendly - try to understand the dependency injection
class depends on a lot of other classes, mocking, seam, learned through hacking,

class:
object graph
construction & lookup
business logic

27:36/32:07
Take Away
 Unit tests are a preferred way of testing

 Unit tests require seperation of instantiation of object graph from business logic under test

Questions:
1. Global variable - make test unpredictable, the order of test matters and so on and so forth.

    Do not clean up after yourself, another test will fail;
    Counter argument: framework than DI framework.

    Monkey-patching - evil on the global state - dependency injection

    C++ / Java / frameworks - dependency injection difference

And read the slideshow using the following link:

http://www.slideshare.net/avalanche123/clean-code-5609451

http://misko.hevery.com/code-reviewers-guide/

http://misko.hevery.com/presentations/

http://misko.hevery.com/2008/10/21/dependency-injection-myth-reference-passing/