# Regression testing¶

When making changes to the Clawpack code base it is a good idea to perform regression tests to insure that the changes have not broken anything.

See also: Keeping track of git versions.

## PyClaw¶

Regression tests can be performed via:

cd $CLAW/pyclaw nosetests  ## Fortran codes¶ A few quick tests can be perfomed of the classic, amrclaw, or geoclaw codes by running make tests in the corresponding tests subdirectory, e.g.: cd$CLAW/classic/tests
make tests


This uses nosetests to run a few Python scripts that in turn run the Fortran codes and then compare a small set of values derived from the output of the run with values that are stored in these directories. If one of these tests fails then there is a problem to be investigated, but these tests do not provide good coverage of the code or check that everything is working properly.

A somewhat more complete set of tests can be run by executing all of the codes in the examples subdirectories and comparing the resulting plots with those archived in the Galleries of all Clawpack applications. An attempt at automating this can be found in the $CLAW/amrclaw/examples directory, which uses the imagediff tool described below. This is still under development. ## chardiff tool for line-by-line comparison of output files¶ If _output_old and _output_new are two sets of output files from old and new versions of a code, then it is often useful to do a line by line comparison of all of the files in each directory and display any differences. Standard tools such as xxdiff in linux or opendiff on a Mac are not very good for this since they try to match up blocks of lines to give the best match and may not compare the files line by line. The Python script$CLAW/clawutil/src/python/clawutil/chardiff.py can be used for this purpose:

$python$CLAW/clawutil/src/python/clawutil/chardiff.py _output_old _output_new


will create a new directory with html files showing all differences. It can also be used to compare two individual files. See the docstring for more details.

## imagediff tool for pixel comparison of plots¶

If _plots_old and _plots_new contain two sets of plots that we hope are identical, the Python script $CLAW/clawutil/src/python/clawutil/imagediff.py can be used to compare the corresponding images in each directory and produce html files that show each pair of images side by side. If the images are not identical it also shows an image indicating which pixels are different in the two: $ python \$CLAW/clawutil/src/python/clawutil/imagediff.py _plots_old _plots_new


will create a new directory with html files showing all differences. It can also be used to compare two individual files. See the docstring for more details.

## Travis continuous integration¶

Most Clawpack git repositories now contain a file .travis.yml at the top level so that every time a pull request is issued on Github, a basic set of tests is run. This uses the Travis continuous integration platform. Shortly after a PR is issued, Travis will run the commands in the .travis.yml and report the results on the PR page. Look for a green check mark (good) or a red X (bad) next to a commit hash and click on it to see the Travis output. [Sample output]