Update README.md

README.md

+# OPAL regression tests
 
+## Introduction
+
+The _OPAL_ regression tests are mantained in this repository. To run all
+(active) tests, you have to compile _OPAL_ with all relevant features
+enabled (AMR, AMR_MG_SOLVER, BANDRF, MSLANG, OPAL_FEL, SAAMG_SOLVER).
+
+## Directory hierarchy
+
+`RegressionTests`: active regression tests.
+
+`DisabledTests`: tests which are somehow broken and require a review.
+
+## Running a single regression tests
+
+* Setup the environment required to run _OPAL_ (e.g. by loading required modules)
+* Set the environment variable `OPAL_EXE_PATH` to the directory where the `opal` binary is located.
+* Run the script `<TEST>.local` (replace `<TEST>` with the name of the regression test to run).
+
+Notes:
+* You can but don't have to change into the directory of the regression test. For example: You can start the AWAGun-1 test with the command `./RegressionTests/AWAGun-1/AWAGun-1.local`.
+* With the above steps, a regression test is performed, but the results are not verified! The verification must be done in a seperate step, see below.
+
+## Verifing the result of a regression test
+
+The results of a regression test can be verified with the tool `verify_test` which is available in the NightlyBuild repository:
+```
+verify_test <DIR_OF_TEST>
+```
+if the script is in available via `PATH` or otherwise
+```
+<DIR>/verify_test <DIR_OF_TEST>
+```
+(replace `<DIR>` with the directory where the script is located).
+
+Example:
+```
+verify_test RegressionTests/AWAGun-1
+```
+
+Notes:
+* `verify_test` is written in Python and requires some non-default modules like pathlib. You might have to setup our own Python environment. At PSI you can use the module `Python/3.6.3`.
+
+## Run and verify all regression test
+
+* setup environment to run _OPAL_ (don't forget to set `OPAL_EXE_PATH`)
+* clone this repository
+* cd into the cloned repository
+* run all tests
+```
+for test in ./RegressionTests/*; do
+    ${test}/*.local
+done
+```
+* verify all tests
+```
+VERIFY_TEST_DIR=<DIR>
+for test in ./RegressionTests/*; do
+    ${VERIY_TEST_DIR}/verify_test ${test}
+done
+```