A DESCRIPTION OF THE SELECTOR TEST FRAMEWORK

When writing tests for selectors, I found that I wanted to have some
standard way of working with a set of files and testing whether one or
another of them was selected. To that end, I created a base class called
BaseSelectorTest that does most of the heavy lifting. Of course, you can
test your selectors any way you want, but if you want to reuse this code,
read on.

What BaseSelectorTest does is use an ant build file
"src/etc/testcases/types/selector.xml" to copy a tree of files out of
"src/etc/testcases/taskdefs/expected" into a "selectortest" directories.
Then it takes a list of 12 of the files and directories in this tree, and
applies whatever selector you pass in to each one. It passes back to your
test a 12 character long string indicating which of the 12 files and
directories was selected, using 'T' for selected and 'F' for not selected.
In the Test class for your selector, you override the getInstance() method
to create your own type of selector, and set the elements of your selector
a variety of ways to ensure that the string of T's and F's returned when
the selector is applied to those 12 files is correct.

So, for example, DepthSelectorTest.java extends BaseSelectorTest and has
the following code:


    public BaseSelector getInstance() {
        return new DepthSelector();
    }


    public void testSelectionBehaviour() {
        DepthSelector s;
        String results;


        try {
            makeBed();


            s = (DepthSelector) getInstance();
            s.setMin(20);
            s.setMax(25);
            results = selectionString(s);
            assertEquals("FFFFFFFFFFFF", results);


            s = (DepthSelector) getInstance();
            s.setMin(0);
            results = selectionString(s);
            assertEquals("TTTTTTTTTTTT", results);


            s = (DepthSelector) getInstance();
            s.setMin(1);
            results = selectionString(s);
            assertEquals("FFFFFTTTTTTT", results);


The first test says that none of the 12 files or directories will match if
the depth range for the selector is between 20 and 25 (that would be one
deep directory tree!). The second says that all files and directories
match if the minimum depth is set to 0 and the maximum isn't specified. The
third test says that if the minumum depth is 1, the first 5 entries in the
list of 12 will not be selected and the rest will.


You can find the 12 files and directories that are tested for selection in
the BaseSelectorTest class. I used a fixed list so that if someone added
new files to the src/etc/testcases/types directory it wouldn't break my
tests:


    protected String[] filenames = {".","asf-logo.gif.md5","asf-
    logo.gif.bz2",
            "asf-logo.gif.gz","copy.filterset.filtered","zip/asf-
            logo.gif.zip",
            "tar/asf-logo.gif.tar","tar/asf-logo-huge.tar.gz",
            "tar/gz/asf-logo.gif.tar.gz","tar/bz2/asf-logo.gif.tar.bz2",
            "tar/bz2/asf-logo-huge.tar.bz2","tar/bz2"};


If you wish to use this set of files and directories to test your selector,
you can reuse the BaseSelectorTest with no change to it.

You may find you need to alter the build file so that you get some
variation in the files that your selector can work with. Most of the core
selectors have required that kind of modification. If you do that, make
sure that it doesn't alter the output strings on the other selector test,
or if it does that you update their expected return results.

You may also want to alter the set of files you look at in a particular
selector test. Since the filelist in BaseSelectorTest is protected, you
should be able to override it as you need to. Or you can alter the fileset
in BaseSelectorTest itself, provided you update the test strings in all the
other unit tests.

