Run 3 Scouting format tests, read old versions in unit test

DataFormats/Scouting/README.md

@@ -0,0 +1,10 @@
+#  DataFormats/Scouting
+
+## Scouting Data Formats
+
+Any changes to the Scouting data formats must be backwards compatible. In order to ensure the Scouting formats can be read by all future CMSSW releases, there is a `TestRun3ScoutingDataFormats` unit test, which makes use of the `TestReadRun3Scouting` analyzer and the `TestWriteRun3Scouting` producer. The unit test checks that the objects can be read properly from
+
+* a file written by the same release
+* files written by (some) earlier releases
+
+If the persistent format of any Scouting data format gets changed in the future, please adjust the `TestReadRun3Scouting` and `TestWriteRun3Scouting` modules accordingly. It is important that every member container has some content in this test. Please also add a new file to the [https://github.com/cms-data/DataFormats-Scouting/](https://github.com/cms-data/DataFormats-Scouting/) repository, and update the `TestRun3ScoutingDataFormats` unit test to read the newly created file. The file name should contain the release or pre-release with which it was written. There will probably be analogous tests added in the future for run 2 and future runs which will need similar maintenance, although it is unlikely the run 2 formats will change anymore.

DataFormats/Scouting/test/TestRun3ScoutingFormats.sh

@@ -10,4 +10,34 @@ file=testRun3Scouting.root
 
 cmsRun ${LOCAL_TEST_DIR}/test_readRun3Scouting_cfg.py "$file" || die "Failure using test_readRun3Scouting_cfg.py $file" $?
 
+# The old files read below were generated as follows.
+# testRun3Scouting_CMSSW_12_4_0.root: Check out the 12_4_0
+# release and cherry pick the commit that adds the original
+# version of the file DataFormats/Scouting/test/TestWriteRun3Scouting.cc
+# (6 files added by that commit). There will be a conflict
+# with BuildFile.xml and you will need to delete the two
+# unrelated lines).
+#
+# testRun3Scouting_CMSSW_13_0_3.root: Check out the 13_0_3
+# release and cherry pick the commit that adds the original
+# version of the file DataFormats/Scouting/test/TestWriteRun3Scouting.cc
+# (6 files added by that commit). There will be the same
+# conflict with BuildFile.xml and you will need to delete the two
+# unrelated lines). Also add the second commit modifying that
+# file.
+#
+# Run the create_Run3Scouting_test_file.py configuration and
+# rename the file it creates.
+#
+# 12_4_0 was chosen because that release was used for 2022 data.
+# 13_0_3 is being used for 2023 data.
+
+file=testRun3Scouting_CMSSW_12_4_0.root
+inputfile=$(edmFileInPath DataFormats/Scouting/data/$file) || die "Failure edmFileInPath DataFormats/Scouting/data/$file" $?
+cmsRun ${LOCAL_TEST_DIR}/test_readRun3Scouting_CMSSW_12_4_0_cfg.py "$inputfile" || die "Failed to read old file $file" $?
+
+file=testRun3Scouting_CMSSW_13_0_3.root
+inputfile=$(edmFileInPath DataFormats/Scouting/data/$file) || die "Failure edmFileInPath DataFormats/Scouting/data/$file" $?
+cmsRun ${LOCAL_TEST_DIR}/test_readRun3Scouting_cfg.py "$inputfile" || die "Failed to read old file $file" $?
+
 exit 0