How can I see normal print output created during pytest run

Question

Sometimes I want to just insert some print statements in my code  and see what gets printed out when I exercise it  My usual way to  exercise  it is with existing pytest tests  But when I run these  I don t seem able to see any standard output  at least from within PyCharm  my IDE    Is there a simple way to see standard output during a pytest run

User · Answer

When running the test use the -s option  All print statements in exampletest py would get printed on the console when test is run   py test exampletest py -s

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You can also enable  live-logging by setting the following in pytest ini or tox ini in your project root   pytest  log cli   True  Or specify it directly on cli pytest -o log cli True

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According to pytest documentation  version 3 of pytest can temporary disable capture in a test   def test disabling capturing capsys       print  this output is captured       with capsys disabled            print  output not captured  going directly to sys stdout       print  this output is also captured

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pytest test name py -v -s  Simple

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Try   pytest -s -v test login py for more info in console   -v it s a short --verbose  -s means  disable all capturing

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The other answers don t work  The only way to see the captured output is using the following flag      pytest --show-capture all

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If you are using PyCharm IDE  then you can run that individual test or all tests using Run toolbar  The Run tool window displays output generated by your application and you can see all the print statements in there as part of test output

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pytest --capture tee-sys was recently added  v5 4 0   You can capture as well as see the output on stdout err

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In an upvoted comment to the accepted answer  Joe asks      Is there any way to print to the console AND capture the output so that it shows in the junit report    In UNIX  this is commonly referred to as teeing  Ideally  teeing rather than capturing would be the py test default  Non-ideally  neither py test nor any existing third-party py test plugin     that I know of  anyway  supports teeing     despite Python trivially supporting teeing out-of-the-box   Monkey-patching py test to do anything unsupported is non-trivial  Why  Because    Most py test functionality is locked behind a private  pytest package not intended to be externally imported  Attempting to do so without knowing what you re doing typically results in the public pytest package raising obscure exceptions at runtime  Thanks alot  py test  Really robust architecture you got there  Even when you do figure out how to monkey-patch the private  pytest API in a safe manner  you have to do so before running the public pytest package run by the external py test command  You cannot do this in a plugin  e g   a top-level conftest module in your test suite   By the time py test lazily gets around to dynamically importing your plugin  any py test class you wanted to monkey-patch has long since been instantiated     and you do not have access to that instance  This implies that  if you want your monkey-patch to be meaningfully applied  you can no longer safely run the external py test command  Instead  you have to wrap the running of that command with a custom setuptools test command that  in order     Monkey-patches the private  pytest API  Calls the public pytest main   function to run the py test command     This answer monkey-patches py test s -s and --capture no options to capture stderr but not stdout  By default  these options capture neither stderr nor stdout  This isn t quite teeing  of course  But every great journey begins with a tedious prequel everyone forgets in five years   Why do this  I shall now tell you  My py test-driven test suite contains slow functional tests  Displaying the stdout of these tests is helpful and reassuring  preventing leycec from reaching for killall -9 py test when yet another long-running functional test fails to do anything for weeks on end  Displaying the stderr of these tests  however  prevents py test from reporting exception tracebacks on test failures  Which is completely unhelpful  Hence  we coerce py test to capture stderr but not stdout   Before we get to it  this answer assumes you already have a custom setuptools test command invoking py test  If you don t  see the Manual Integration subsection of py test s well-written Good Practices page   Do not install pytest-runner  a third-party setuptools plugin providing a custom setuptools test command also invoking py test  If pytest-runner is already installed  you ll probably need to uninstall that pip3 package and then adopt the manual approach linked to above   Assuming you followed the instructions in Manual Integration highlighted above  your codebase should now contain a PyTest run tests   method  Modify this method to resemble   class PyTest TestCommand                                                    def run tests self             Import the public  pytest  package  BEFORE  the private   pytest            package  While importation order is typically ignorable  imports can           technically have side effects  Tragicomically  that is the case here            Importing the public  pytest  package establishes runtime           configuration required by submodules of the private   pytest  package            The former  MUST  always be imported before the latter  Failing to do           so raises obtuse exceptions at runtime    which is bad          import pytest         from  pytest capture import CaptureManager  FDCapture  MultiCapture            If the private method to be monkey-patched no longer exists  py test           is either broken or unsupported  In either case  raise an exception          if not hasattr CaptureManager    getcapture                from distutils errors import DistutilsClassError             raise DistutilsClassError                   Class  pytest capture CaptureManager  method  getcapture                      not found  The current version of py test is either                    broken  unlikely  or unsupported  likely                             Old method to be monkey-patched           getcapture old   CaptureManager  getcapture            New method applying this monkey-patch  Note the use of                         out False    NOT  capturing stdout               err True   capturing stderr          def  getcapture new self  method               if method     no                   return MultiCapture                      out False  err True  in  False  Capture FDCapture              else                  return  getcapture old self  method             Replace the old with the new method          CaptureManager  getcapture    getcapture new            Run py test with all passed arguments          errno   pytest main self pytest args          sys exit errno    To enable this monkey-patch  run py test as follows   python setup py test -a  -s    Stderr but not stdout will now be captured  Nifty   Extending the above monkey-patch to tee stdout and stderr is left as an exercise to the reader with a barrel-full of free time

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The -s switch disables per-test capturing  only if a test fails

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pytest captures the stdout from individual tests and displays them only on certain conditions  along with the summary of the tests it prints by default   Extra summary info can be shown using the  -r  option   pytest -rP   shows the captured output of passed tests   pytest -rx   shows the captured output of failed tests  default behaviour    The formatting of the output is prettier with -r than with -s

[python] How can I see normal print output created during pytest run?

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