Implement EventIDProducer and EventIDValidator

EventIDProducer reads the EventID from the current event and copies it
into the Event as a data product.

EventIDValidator reads the EventID from the current event and compares
it to a data product read from the Event.

They can be used to validate that an object produced in a given event is
being read back in the same event.

FWCore/TestModules/README.md

@@ -4,6 +4,23 @@ This package contains modules that are used in framework tests, but
 are generic-enough to be usable outside of the framework as well.
 Their interfaces are intended to be relatively stable.
 
+
 ## `edmtest::StreamIDFilter`
 
 This module can be used to reject all events in specific streams.
+
+
+## `edmtest::EventIDProducer`
+
+This module reads the `EventID` from the current event and copies it as
+a data product into the `Event`.
+
+
+## `edmtest::EventIDValidator`
+
+This module reads the `EventID` from the current event and compares it
+to a data product read from the `Event`.
+
+Together `edmtest::EventIDProducer` and `edmtest::EventIDValidator` can
+be used to validate that an object produced in a given event is being
+read back in the same event.

FWCore/TestModules/plugins/BuildFile.xml

@@ -1,5 +1,8 @@
+<use name="DataFormats/Provenance"/>
 <use name="FWCore/Framework"/>
+<use name="FWCore/ParameterSet"/>
 <use name="FWCore/PluginManager"/>
+<use name="FWCore/Utilities"/>
 <library file="*.cc" name="FWCoreTestModulesPlugins">
   <flags EDM_PLUGIN="1"/>
 </library>

FWCore/TestModules/plugins/EventIDProducer.cc

@@ -0,0 +1,31 @@
+// CMSSW include files
+#include "DataFormats/Provenance/interface/EventID.h"
+#include "FWCore/Framework/interface/Event.h"
+#include "FWCore/Framework/interface/global/EDProducer.h"
+#include "FWCore/ParameterSet/interface/ConfigurationDescriptions.h"
+#include "FWCore/ParameterSet/interface/ParameterSetDescription.h"
+#include "FWCore/Utilities/interface/EDPutToken.h"
+
+namespace edmtest {
+
+  class EventIDProducer : public edm::global::EDProducer<> {
+  public:
+    EventIDProducer(edm::ParameterSet const& config) : token_(produces()) {}
+
+    void produce(edm::StreamID, edm::Event& event, edm::EventSetup const&) const final {
+      event.emplace(token_, event.id());
+    }
+
+    static void fillDescriptions(edm::ConfigurationDescriptions& descriptions) {
+      edm::ParameterSetDescription desc;
+      descriptions.addWithDefaultLabel(desc);
+    }
+
+  private:
+    edm::EDPutTokenT<edm::EventID> token_;
+  };
+
+}  // namespace edmtest
+
+#include "FWCore/Framework/interface/MakerMacros.h"
+DEFINE_FWK_MODULE(edmtest::EventIDProducer);

FWCore/TestModules/plugins/EventIDValidator.cc

@@ -0,0 +1,43 @@
+// C++ include files
+#include <sstream>
+#include <stdexcept>
+
+// CMSSW include files
+#include "DataFormats/Provenance/interface/EventID.h"
+#include "FWCore/Framework/interface/Event.h"
+#include "FWCore/Framework/interface/global/EDAnalyzer.h"
+#include "FWCore/ParameterSet/interface/ConfigurationDescriptions.h"
+#include "FWCore/ParameterSet/interface/ParameterSetDescription.h"
+#include "FWCore/Utilities/interface/EDGetToken.h"
+
+namespace edmtest {
+
+  class EventIDValidator : public edm::global::EDAnalyzer<> {
+  public:
+    EventIDValidator(edm::ParameterSet const& config)
+        : token_(consumes(config.getUntrackedParameter<edm::InputTag>("source"))) {}
+
+    void analyze(edm::StreamID, edm::Event const& event, edm::EventSetup const&) const final {
+      auto const& id = event.get(token_);
+      if (id != event.id()) {
+        std::ostringstream msg;
+        msg << "EventIDValidator: found invalid input value\n" << id << "\nwhile expecting\n" << event.id();
+        throw std::logic_error(msg.str());
+      }
+    }
+
+    static void fillDescriptions(edm::ConfigurationDescriptions& descriptions) {
+      edm::ParameterSetDescription desc;
+      desc.addUntracked("source", edm::InputTag{"eventIDProducer", ""})
+          ->setComment("EventID product to read from the event");
+      descriptions.addWithDefaultLabel(desc);
+    }
+
+  private:
+    edm::EDGetTokenT<edm::EventID> token_;
+  };
+
+}  // namespace edmtest
+
+#include "FWCore/Framework/interface/MakerMacros.h"
+DEFINE_FWK_MODULE(edmtest::EventIDValidator);

FWCore/TestModules/test/BuildFile.xml

@@ -0,0 +1 @@
+<test name="TestFWCoreModulesEventIDValidator" command="cmsRun ${LOCALTOP}/src/FWCore/TestModules/test/testEventIDValidator_cfg.py"/>

FWCore/TestModules/test/testEventIDValidator_cfg.py

@@ -0,0 +1,18 @@
+import FWCore.ParameterSet.Config as cms
+
+process = cms.Process("TEST")
+
+process.options.numberOfThreads = 4
+process.options.numberOfStreams = 4
+
+process.source = cms.Source("EmptySource")
+
+process.maxEvents.input = 100
+
+process.eventIds = cms.EDProducer("EventIDProducer")
+
+process.eventValidator = cms.EDAnalyzer("EventIDValidator",
+    source = cms.untracked.InputTag('eventIds')
+)
+
+process.path = cms.Path(process.eventIds + process.eventValidator)