greptest.md

+The `parabix-devel/QA` directory contains a number of testing scripts and data files.
+
+To test `icgrep`, `greptest.py` can be used.   It works with a file specifying test cases, such as `greptest.xml`.
+
+Inside `greptest.xml`, you can include sample test files for grep searches using the `datafile` element.   For example, the test file `simple1` is declared as follows.
+```
+<datafile id="simple1">
+A few lines of input
+in this simple test file
+provide fodder for some simple
+regexp tests.
+</datafile>
+```
+
+Test cases can then be written with the `grepcase` element.
+For example, an `icgrep` search using the regular expression `fe|si` should return matches for lines 2, 3 and 4 of the test file `simple1`.   This is declared using the following `grepcase` element.
+
+```
+<grepcase regexp="fe|si" datafile="simple1" greplines="2 3 4"/>
+```
+
+Any tests included in `greptest.xml` are automatically run as part of the `make check` process.
+
+You can also run tests directly from the parabix-devel/QA directory.
+For example, if you want to run the tests, but print out the expected and actual input and output each time, you can use the following commands.
+```
+cd QA
+python greptest.py -v ../build/bin/icgrep
+```