Tide: trigger jobs that are required by Gerrit

Jobs required are different between GitHub and Gerrit. For GitHub they are defined on the job config, and for Gerrit it depends on whether the Gerrit label the prowjob votes on is also required by Gerrit

prow/tide/codereview.go

@@ -249,4 +249,8 @@ type provider interface {
 
 	refsForJob(sp subpool, prs []CodeReviewCommon) (prowapi.Refs, error)
 	labelsAndAnnotations(instance string, jobLabels, jobAnnotations map[string]string, changes ...CodeReviewCommon) (labels, annotations map[string]string)
+
+	// jobIsRequiredByTide is defined by each provider for figuring out whether
+	// a job is required by Tide or not.
+	jobIsRequiredByTide(ps *config.Presubmit, pr *CodeReviewCommon) bool
 }

prow/tide/gerrit.go

@@ -481,3 +481,23 @@ func (p *GerritProvider) labelsAndAnnotations(instance string, jobLabels, jobAnn
 	labels, annotations = gerritadaptor.LabelsAndAnnotations(instance, jobLabels, jobAnnotations, changes...)
 	return
 }
+
+func (p *GerritProvider) jobIsRequiredByTide(ps *config.Presubmit, crc *CodeReviewCommon) bool {
+	if ps.RunBeforeMerge {
+		return true
+	}
+
+	pr := crc.Gerrit
+	requireLabels := sets.NewString()
+	for l, info := range pr.Labels {
+		if !info.Optional {
+			requireLabels.Insert(l)
+		}
+	}
+
+	val, ok := ps.Labels[kube.GerritReportLabel]
+	if !ok {
+		return false
+	}
+	return requireLabels.Has(val)
+}

prow/tide/gerrit_test.go

@@ -944,3 +944,57 @@ func TestPrMergeMethod(t *testing.T) {
 		})
 	}
 }
+
+func TestJobIsRequiredByTide(t *testing.T) {
+	tests := []struct {
+		name string
+		ps   *config.Presubmit
+		crc  *CodeReviewCommon
+		want bool
+	}{
+		{
+			name: "default",
+			ps:   &config.Presubmit{},
+			crc: &CodeReviewCommon{
+				Gerrit: &gerrit.ChangeInfo{Labels: map[string]gerrit.LabelInfo{}},
+			},
+		},
+		{
+			name: "run-before-merge",
+			ps:   &config.Presubmit{RunBeforeMerge: true},
+			crc: &CodeReviewCommon{
+				Gerrit: &gerrit.ChangeInfo{Labels: map[string]gerrit.LabelInfo{}},
+			},
+			want: true,
+		},
+		{
+			name: "required-label",
+			ps: &config.Presubmit{JobBase: config.JobBase{Labels: map[string]string{
+				"prow.k8s.io/gerrit-report-label": "Verified-By-Prow",
+			}}},
+			crc: &CodeReviewCommon{
+				Gerrit: &gerrit.ChangeInfo{Labels: map[string]gerrit.LabelInfo{"Verified-By-Prow": {}}},
+			},
+			want: true,
+		},
+		{
+			name: "optional-label",
+			ps: &config.Presubmit{JobBase: config.JobBase{Labels: map[string]string{
+				"prow.k8s.io/gerrit-report-label": "Verified-By-Prow",
+			}}},
+			crc: &CodeReviewCommon{
+				Gerrit: &gerrit.ChangeInfo{Labels: map[string]gerrit.LabelInfo{"Verified-By-Prow": {Optional: true}}},
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			fc := &GerritProvider{}
+			if want, got := tc.want, fc.jobIsRequiredByTide(tc.ps, tc.crc); want != got {
+				t.Errorf("Wrong. Want: %v, got: %v", want, got)
+			}
+		})
+	}
+}

prow/tide/github.go

@@ -416,6 +416,10 @@ func (gi *GitHubProvider) labelsAndAnnotations(instance string, jobLabels, jobAn
 	return
 }
 
+func (gi *GitHubProvider) jobIsRequiredByTide(ps *config.Presubmit, pr *CodeReviewCommon) bool {
+	return ps.ContextRequired() || ps.RunBeforeMerge
+}
+
 // dateToken generates a GitHub search query token for the specified date range.
 // See: https://help.github.com/articles/understanding-the-search-syntax/#query-for-dates
 func dateToken(start, end time.Time) string {

prow/tide/tide.go

@@ -22,6 +22,7 @@ package tide
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net/http"
 	"sort"
@@ -1557,7 +1558,7 @@ func (c *syncController) presubmitsByPull(sp *subpool) (map[int][]config.Presubm
 		log.WithField("num_possible_presubmit", len(presubmitsForPull)).Debug("Found possible presubmits")
 
 		for _, ps := range presubmitsForPull {
-			if !ps.ContextRequired() {
+			if !c.provider.jobIsRequiredByTide(&ps, &pr) {
 				continue
 			}
 
@@ -1591,6 +1592,11 @@ func (c *syncController) presubmitsByPull(sp *subpool) (map[int][]config.Presubm
 func (c *syncController) presubmitsForBatch(prs []CodeReviewCommon, org, repo, baseSHA, baseBranch string) ([]config.Presubmit, error) {
 	log := c.logger.WithFields(logrus.Fields{"repo": repo, "org": org, "base-sha": baseSHA, "base-branch": baseBranch})
 
+	if len(prs) == 0 {
+		log.Debug("No PRs, skip looking for presubmits for batch.")
+		return nil, errors.New("no PRs are provided")
+	}
+
 	var headRefGetters []config.RefGetter
 	for _, pr := range prs {
 		headRefGetters = append(headRefGetters, refGetterFactory(pr.HeadRefOID))
@@ -1604,7 +1610,7 @@ func (c *syncController) presubmitsForBatch(prs []CodeReviewCommon, org, repo, b
 
 	var result []config.Presubmit
 	for _, ps := range presubmits {
-		if !ps.ContextRequired() {
+		if !c.provider.jobIsRequiredByTide(&ps, &prs[0]) {
 			continue
 		}