Throw on missing file in ChainEvent, revive unit tests that would have caught this

[dan131riley]

PR description:

As recently revealed when an unit test input file disappeared, fwlite::ChainEvent() doesn't check the value of TFile::Open() and so segfaults on missing files. This PR corrects the bug and revives and modernizes an old unit test that would have caught this.

PR validation:

Revived the unit test. Verified that it segfaulted. Modified fwlite::ChainEvent() to throw instead of faulting, verified that the unit test succeeded.

[cmsbuild]

-code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-33550/22331

• This PR adds an extra 28KB to repository

Code check has found code style and quality issues which could be resolved by applying following patch(s)

• code-format:
  https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-33550/22331/code-format.patch
  e.g. curl https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-33550/22331/code-format.patch | patch -p1
  You can also run scram build code-format to apply code format directly

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-33550/22332

• This PR adds an extra 28KB to repository

[cmsbuild]

A new Pull Request was created by @dan131riley (Dan Riley) for master.

It involves the following packages:

DataFormats/FWLite

@makortel, @smuzaffar, @cmsbuild, @Dr15Jones can you please review it and eventually sign? Thanks.
@makortel, @wddgit, @rovere this is something you requested to watch as well.
@silviodonato, @dpiparo, @qliphy you are the release manager for this.

cms-bot commands are listed here

[makortel]

@cmsbuild, please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-4506e0/14642/summary.html
COMMIT: b3712fd
CMSSW: CMSSW_12_0_X_2021-04-27-1100/slc7_amd64_gcc900
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/33550/14642/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 3034 differences found in the comparisons
• DQMHistoTests: Total files compared: 38
• DQMHistoTests: Total histograms compared: 2877605
• DQMHistoTests: Total failures: 7706
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2869877
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 37 files compared)
• Checked 160 log files, 37 edm output root files, 38 DQM output files
• TriggerResults: found differences in 1 / 37 workflows

[makortel]

Comparison differences are not related to changes in this PR.

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-33550/22375

• This PR adds an extra 24KB to repository

[cmsbuild]

Pull request #33550 was updated. @makortel, @smuzaffar, @cmsbuild, @Dr15Jones can you please check and sign again.

[makortel]

@cmsbuild, please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-4506e0/14702/summary.html
COMMIT: 6fd33f5
CMSSW: CMSSW_12_0_X_2021-04-29-0800/slc7_amd64_gcc900
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/33550/14702/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 0 differences found in the comparisons
• DQMHistoTests: Total files compared: 38
• DQMHistoTests: Total histograms compared: 2877605
• DQMHistoTests: Total failures: 3
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2877580
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 37 files compared)
• Checked 160 log files, 37 edm output root files, 38 DQM output files
• TriggerResults: no differences found

[makortel]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next master IBs (tests are also fine). This pull request will now be reviewed by the release team before it's merged. @silviodonato, @dpiparo, @qliphy (and backports should be raised in the release meeting by the corresponding L2)

[silviodonato]

+1