prow/statusreconciler/controller.go
func addedBlockingPresubmits(old, new map[string][]config.Presubmit) map[string][]config.Presubmit {
	added := map[string][]config.Presubmit{}

	for repo, oldPresubmits := range old {
		added[repo] = []config.Presubmit{}
		for _, newPresubmit := range new[repo] {
			if !newPresubmit.ContextRequired() || newPresubmit.NeedsExplicitTrigger() {
				continue
			}
			var found bool
			for _, oldPresubmit := range oldPresubmits {
				if oldPresubmit.Name == newPresubmit.Name {
					if oldPresubmit.SkipReport && !newPresubmit.SkipReport {
						added[repo] = append(added[repo], newPresubmit)
						logrus.WithFields(logrus.Fields{
							"repo": repo,
							"name": oldPresubmit.Name,
						}).Debug("Identified a newly-reporting blocking presubmit.")
					}
					if oldPresubmit.RunIfChanged != newPresubmit.RunIfChanged {
						added[repo] = append(added[repo], newPresubmit)
						logrus.WithFields(logrus.Fields{
							"repo": repo,
							"name": oldPresubmit.Name,
						}).Debug("Identified a blocking presubmit running over a different set of files.")
					}
					found = true
					break
				}
			}
			if !found {
				added[repo] = append(added[repo], newPresubmit)
				logrus.WithFields(logrus.Fields{
					"repo": repo,
					"name": newPresubmit.Name,
				}).Debug("Identified an added blocking presubmit.")
			}
		}
	}

	var numAdded int
	for _, presubmits := range added {
		numAdded += len(presubmits)
	}
	logrus.Infof("Identified %d added blocking presubmits.", numAdded)
	return added
}
func addedBlockingPresubmits(old, new map[string][]config.Presubmit) map[string][]config.Presubmit {
	added := map[string][]config.Presubmit{}

	for repo, oldPresubmits := range old {
		added[repo] = []config.Presubmit{}
		for _, newPresubmit := range new[repo] {
			if !newPresubmit.ContextRequired() || newPresubmit.NeedsExplicitTrigger() {
				continue
			}
			var found bool
			for _, oldPresubmit := range oldPresubmits {
				if oldPresubmit.Name == newPresubmit.Name {
					if oldPresubmit.SkipReport && !newPresubmit.SkipReport {
						added[repo] = append(added[repo], newPresubmit)
						logrus.WithFields(logrus.Fields{
							"repo": repo,
							"name": oldPresubmit.Name,
						}).Debug("Identified a newly-reporting blocking presubmit.")
					}
					if oldPresubmit.RunIfChanged != newPresubmit.RunIfChanged {
						added[repo] = append(added[repo], newPresubmit)
						logrus.WithFields(logrus.Fields{
							"repo": repo,
							"name": oldPresubmit.Name,
						}).Debug("Identified a blocking presubmit running over a different set of files.")
					}
					found = true
					break
				}
			}
			if !found {
				added[repo] = append(added[repo], newPresubmit)
				logrus.WithFields(logrus.Fields{
					"repo": repo,
					"name": newPresubmit.Name,
				}).Debug("Identified an added blocking presubmit.")
			}
		}
	}

	var numAdded int
	for _, presubmits := range added {
		numAdded += len(presubmits)
	}
	logrus.Infof("Identified %d added blocking presubmits.", numAdded)
	return added
}
// addedBlockingPresubmits determines new blocking presubmits based on a
// config update. New blocking presubmits are either brand-new presubmits
// or extant presubmits that are now reporting. Previous presubmits that
// reported but were optional that are no longer optional require no action
// as their contexts will already exist on PRs.