title: unit test work flow
body: <p>New to unit test. Try to make sure I understand it correctly.</p>
  
  <p>1> I wrote a module "foo111.py", contains one function "add"</p>
  
  <p>2> I want to test "add'. I create a script called "test_foo111.py"</p>
  
  <p>3> in the test script, I create a "test_add", I call it from the main of the test script (pls see picture below)</p>
  
  <p>4> When I click on "main" of the test_foo111.py, the script run in normal debug mode.</p>
  
  <p>5> only when I click on the "test_add" function, the script run in testing mode.</p>
  
  <p>I thought I'm able to call all the test from the main(imagine I will have more functions in foo111), so that I don't need to run all the test one by one???? I think I must mis-understood something here.. 
  step 4
  <a href="https://i.stack.imgur.com/auNAd.jpg" rel="nofollow"><img src="https://i.stack.imgur.com/auNAd.jpg" alt="step 4"></a></p>
  
  <p>step 5
  <a href="https://i.stack.imgur.com/NnqU2.jpg" rel="nofollow"><img src="https://i.stack.imgur.com/NnqU2.jpg" alt="step 5"></a></p>