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1798 :: [feature suggestion] advanced assert

• PV (orginal) [2015-11-12T20:05:36+01:00] view original

  Non-trivial assert should provide as much context as possible, especially when there's no easy-to-use debugger.

  Here are my suggestions:

  1. Assertion message should also show actual values of tested values:

  assert(a > 1)  # show what the value of a is
  assert(foo() > bar.baz()) # show return value of foo() and return value of bar.baz()
  Run

  2. Assert should print any number of specified values:

  assert(a > 1, b, c, d) # show content of b, c and d, whatever type they are
  Run

  3. In really complicated cases assert should invoke attached procedure to show whatever may be interesting in context:

  assert(a > 1):
     var x = foo()
     if bar(x): echo "..."
  Run

  4. Nice to have would be ability to intercept assert output (e.g. reroute it to socket connection) or add more information (e.g. just running unit test).

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• Arrrrrrrrr (orginal) [2015-11-12T20:58:44+01:00] view original

  You can do that with unittest:

  import unittest
  let (a, b) = (123, 321)
  check a == b
  
  # prog.nim(4,8): Check failed: a == b
  # a was 123
  # b was 321
  Run

  http://nim-lang.org/docs/unittest.html

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• PV (orginal) [2015-11-12T21:36:03+01:00] view original

  I had checked it and it is far from what I wished for:

  import unittest
  
  proc foo : int =
    return 1
  
  proc bar : int =
    return 2
  
  let (a, b) = (123, 321)
  check a == b and foo() == bar()
  Run

  shows

  a.nim(12,13): Check failed: a == b and foo() == bar()
  a == b was false
  foo() == bar() was false
  Run

  which is not as informative as it could be. The real code problem is usually complicated and requires lot of context for understanding.

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• PV (orginal) [2015-11-12T21:44:57+01:00] view original

  I was inspired by John Torjo's Smart Assert library:

  http://www.drdobbs.com/cpp/enhancing-assertions/184403745

  (He made even more powerfull version for Boost, but it didn't get through.)

  This library employs preprocessor tricks. Using it, however, caused compilation time to grow significantly, so it was unusable in practice for me.

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• jyapayne (orginal) [2015-11-12T22:49:59+01:00] view original

  It would be awesome to see this integrated into the unittest lib! Perhaps inspiration could be taken from my einheit testing library :) It seems to do what you want.

  For example, the following code:

  import einheit
  
  testSuite TestingValues:
    
    method setup()=
      discard
    
    method tearDown()=
      discard
    
    method testValues()=
      proc foo : int =
        return 1
      
      proc bar : int =
        return 2
      
      let (a, b) = (123, 321)
      self.check(a == b and foo() == bar())
  
  when isMainModule:
    runTests()
  Run

  Outputs:

  
  
  [Running] TestingValues  -------------------------------------------------------
  
  [Failed] testValues
    Condition: check(a == b and foo() == bar())
    Where:
      a -> 123
      bar() -> 2
      b -> 321
      foo() -> 1
    Location: x.nim; line 19
  
  
  [0/1] tests passed for TestingValues. ------------------------------------------
  
  
  [Summary]
    
    [0/1] tests passed.
  Run

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