Writing Unittests for PyPhysim

The standard unittest module is used to implement automated tests for the several packages in the PyPhysim library. The tests are located in the tests folder, which should contain a single test file for each package in PyPhysim.

Each test file contains several test case classes, as usual in the unittests framework. The first test case class is always a Doctests test case, that is, a test case that simple run all the doctests in each module of the package.

After that, a test case class must be implemented for each module in the package, which in turn should test all the classes and functions in that module.

Test Coverage

Ideally unittests should be implemented at the same time the actual code is implemented (or even before that). However, sometimes the tests are implemented the tested code and this may leave code untested.

A good way to make sure that we have a good test coverage in PyPhysim is using the python-coverage program. With it we can run all the implemented unittests and get a report of the lines in any module in PyPhysim that was not run by any unittest (thus finding untested code). The bin folder contains a script called run_python_coverage.sh that will do exactly that.

Code Quality

A good way to ensure code quality, besides implementing unittests, is to employ code analisys tools such as pylint, pep8, pychecker, etc.

For the quality of PyPhysim as a package, see the cheesecake_index tool.

• http://pycheesecake.org/

• http://infinitemonkeycorps.net/docs/pph/

Notes

If you use pylint, this is the .pylintrc file I use (although I don’t struggle to fix every pylint warning)

[MASTER]

# Specify a configuration file.
#rcfile=

# Python code to execute, usually for sys.path manipulation such as
# pygtk.require().
init-hook='import sys; sys.path.append("./"); sys.path.append("../")'

# Profiled execution.
profile=no

# Add files or directories to the blacklist. They should be base names, not
# paths.
ignore=CVS

# Pickle collected data for later comparisons.
persistent=yes

# List of plugins (as comma separated values of python modules names) to load,
# usually to register additional checkers.
load-plugins=


[MESSAGES CONTROL]

# Enable the message, report, category or checker with the given id(s). You can
# either give multiple identifier separated by comma (,) or put this option
# multiple time.
#enable=

# Disable the message, report, category or checker with the given id(s). You
# can either give multiple identifier separated by comma (,) or put this option
# multiple time (only on the command line, not in the configuration file where
# it should appear only once).
disable=C0301,R0903,C0103,W0621,W0511,W0221,W0141,R0921,W0142,E1101,C0325,C0114
# - The warning W0511 correspond to the TODOs in the code
#
# - The warning W0221 correspond to methods in child classes that
#   re-implement a parent method, but with different arguments
#
# - The warning W0141 corresponds to using built-in functions such as map,
#   filter etc. In fact, the same thing these functions do could be done
#   with list comprehensions, but I like using the map function.

[REPORTS]

# Set the output format. Available formats are text, parseable, colorized, msvs
# (visual studio) and html
output-format=text

# Include message's id in output
include-ids=yes

# Put messages in a separate file for each module / package specified on the
# command line instead of printing them on stdout. Reports (if any) will be
# written in a file name "pylint_global.[txt|html]".
files-output=no

# Tells whether to display a full report or only the messages
reports=yes

# Python expression which should return a note less than 10 (10 is the highest
# note). You have access to the variables errors warning, statement which
# respectively contain the number of errors / warnings messages and the total
# number of statements analyzed. This is used by the global evaluation report
# (RP0004).
evaluation=10.0 - ((float(5 * error + warning + refactor + convention) / statement) * 10)

# Add a comment according to your evaluation note. This is used by the global
# evaluation report (RP0004).
comment=no


[BASIC]

# Required attributes for module, separated by a comma
required-attributes=

# List of builtins function names that should not be used, separated by a comma
bad-functions=map,filter,apply,input

# Regular expression which should only match correct module names
module-rgx=(([a-z_][a-z0-9_]*)|([A-Z][a-zA-Z0-9]+))$

# Regular expression which should only match correct module level names
const-rgx=(([A-Z_][A-Z0-9_]*)|(__.*__))$

# Regular expression which should only match correct class names
class-rgx=[A-Z_][a-zA-Z0-9]+$

# Regular expression which should only match correct function names
function-rgx=[a-z_][a-z0-9_]{2,30}$

# Regular expression which should only match correct method names
method-rgx=[a-z_][a-z0-9_]{2,30}$

# Regular expression which should only match correct instance attribute names
attr-rgx=[a-z_][a-z0-9_]{2,30}$

# Regular expression which should only match correct argument names
argument-rgx=[a-z_][a-z0-9_]{2,30}$

# Regular expression which should only match correct variable names
variable-rgx=[a-z_][a-z0-9_]{2,30}$

# Regular expression which should only match correct list comprehension /
# generator expression variable names
inlinevar-rgx=[A-Za-z_][A-Za-z0-9_]*$

# Good variable names which should always be accepted, separated by a comma
good-names=i,j,k,ex,Run,_

# Bad variable names which should always be refused, separated by a comma
bad-names=foo,bar,baz,toto,tutu,tata

# Regular expression which should only match functions or classes name which do
# not require a docstring
#no-docstring-rgx=__.*__  # Default


[FORMAT]

# Maximum number of characters on a single line.
max-line-length=85

# Maximum number of lines in a module
max-module-lines=1500

# String used as indentation unit. This is usually " " (4 spaces) or "\t" (1
# tab).
indent-string='    '


[SIMILARITIES]

# Minimum lines number of a similarity.
min-similarity-lines=4

# Ignore comments when computing similarities.
ignore-comments=yes

# Ignore docstrings when computing similarities.
ignore-docstrings=yes


[VARIABLES]

# Tells whether we should check for unused import in __init__ files.
init-import=no

# A regular expression matching the beginning of the name of dummy variables
# (i.e. not used).
dummy-variables-rgx=_|dummy

# List of additional names supposed to be defined in builtins. Remember that
# you should avoid to define new builtins when possible.
additional-builtins=


[MISCELLANEOUS]

# List of note tags to take in consideration, separated by a comma.
notes=FIXME,XXX,TODO


[TYPECHECK]

# Tells whether missing members accessed in mixin class should be ignored. A
# mixin class is detected if its name ends with "mixin" (case insensitive).
ignore-mixin-members=yes

# List of classes names for which member attributes should not be checked
# (useful for classes with attributes dynamically set).
ignored-classes=SQLObject

# When zope mode is activated, add a predefined set of Zope acquired attributes
# to generated-members.
zope=no

# List of members which are set dynamically and missed by pylint inference
# system, and so shouldn't trigger E0201 when accessed. Python regular
# expressions are accepted.
generated-members=REQUEST,acl_users,aq_parent


[DESIGN]

# Maximum number of arguments for function / method
max-args=7

# Argument names that match this expression will be ignored. Default to name
# with leading underscore
ignored-argument-names=_.*

# Maximum number of locals for function / method body
max-locals=15

# Maximum number of return / yield for function / method body
max-returns=6

# Maximum number of branch for function / method body
max-branchs=12

# Maximum number of statements in function / method body
max-statements=50

# Maximum number of parents for a class (see R0901).
max-parents=7

# Maximum number of attributes for a class (see R0902).
max-attributes=10

# Minimum number of public methods for a class (see R0903).
min-public-methods=2

# Maximum number of public methods for a class (see R0904).
max-public-methods=25


[IMPORTS]

# Deprecated modules which should not be used, separated by a comma
deprecated-modules=regsub,string,TERMIOS,Bastion,rexec

# Create a graph of every (i.e. internal and external) dependencies in the
# given file (report RP0402 must not be disabled)
import-graph=

# Create a graph of external dependencies in the given file (report RP0402 must
# not be disabled)
ext-import-graph=

# Create a graph of internal dependencies in the given file (report RP0402 must
# not be disabled)
int-import-graph=


[CLASSES]

# List of interface methods to ignore, separated by a comma. This is used for
# instance to not check methods defines in Zope's Interface base class.
ignore-iface-methods=isImplementedBy,deferred,extends,names,namesAndDescriptions,queryDescriptionFor,getBases,getDescriptionFor,getDoc,getName,getTaggedValue,getTaggedValueTags,isEqualOrExtendedBy,setTaggedValue,isImplementedByInstancesOf,adaptWith,is_implemented_by

# List of method names used to declare (i.e. assign) instance attributes.
defining-attr-methods=__init__,__new__,setUp

# List of valid names for the first argument in a class method.
valid-classmethod-first-arg=cls


[EXCEPTIONS]

# Exceptions that will emit a warning when being caught. Defaults to
# "Exception"
overgeneral-exceptions=Exception