prowgen: generate stricter branch: stanzas for presubmits

cmd/ci-operator-prowgen/testdata/zz_fixture_presubmit_TestFromCIOperatorConfigToProwYaml_Input_is_YAML_and_it_is_correctly_processed.yaml

@@ -3,7 +3,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - branch
+    - ^branch$
+    - ^branch-
     context: ci/prow/images
     decorate: true
     decoration_config:
@@ -50,7 +51,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - branch
+    - ^branch$
+    - ^branch-
     context: ci/prow/unit
     decorate: true
     decoration_config:

cmd/ci-operator-prowgen/testdata/zz_fixture_presubmit_TestFromCIOperatorConfigToProwYaml_Using_a_variant_config__one_test_and_images__one_existing_job._Expect_one_presubmit__pre_post_submit_images_jobs._Existing_job_should_not_be_changed..yaml

@@ -3,7 +3,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - branch
+    - ^branch$
+    - ^branch-
     context: ci/prow/rhel-images
     decorate: true
     decoration_config:
@@ -52,7 +53,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - branch
+    - ^branch$
+    - ^branch-
     context: ci/prow/rhel-unit
     decorate: true
     decoration_config:

cmd/ci-operator-prowgen/testdata/zz_fixture_presubmit_TestFromCIOperatorConfigToProwYaml_one_test_and_images__no_previous_jobs._Expect_test_presubmit__pre_post_submit_images_jobs.yaml

@@ -3,7 +3,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - branch
+    - ^branch$
+    - ^branch-
     context: ci/prow/images
     decorate: true
     decoration_config:
@@ -50,7 +51,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - branch
+    - ^branch$
+    - ^branch-
     context: ci/prow/unit
     decorate: true
     decoration_config:

pkg/jobconfig/files.go

@@ -34,6 +34,11 @@ const (
 	PeriodicPrefix         = "periodic"
 )
 
+// SimpleBranchRegexp matches a branch name that does not appear to be a regex (lacks wildcard,
+// group, or other modifiers). For instance, `master` is considered simple, `master-.*` would
+// not.
+var SimpleBranchRegexp = regexp.MustCompile(`^[\w\-.]+$`)
+
 // Info describes the metadata for a Prow job configuration file
 type Info struct {
 	Org    string

pkg/prowgen/prowgen.go

@@ -445,7 +445,7 @@ func generatePresubmitForTest(name string, info *ProwgenInfo, podSpec *corev1.Po
 	return &prowconfig.Presubmit{
 		JobBase:   base,
 		AlwaysRun: true,
-		Brancher:  prowconfig.Brancher{Branches: []string{info.Branch}},
+		Brancher:  prowconfig.Brancher{Branches: sets.NewString(exactlyBranch(info.Branch), featureBranch(info.Branch)).List()},
 		Reporter: prowconfig.Reporter{
 			Context: fmt.Sprintf("ci/prow/%s", shortName),
 		},
@@ -458,7 +458,7 @@ func generatePostsubmitForTest(name string, info *ProwgenInfo, podSpec *corev1.P
 	base := generateJobBase(name, jc.PostsubmitPrefix, info, podSpec, false, pathAlias, jobRelease, skipCloning)
 	return &prowconfig.Postsubmit{
 		JobBase:  base,
-		Brancher: prowconfig.Brancher{Branches: []string{makeBranchExplicit(info.Branch)}},
+		Brancher: prowconfig.Brancher{Branches: []string{exactlyBranch(info.Branch)}},
 	}
 }
 
@@ -613,21 +613,25 @@ func generateJobBase(name, prefix string, info *ProwgenInfo, podSpec *corev1.Pod
 	return base
 }
 
-// simpleBranchRegexp matches a branch name that does not appear to be a regex (lacks wildcard,
-// group, or other modifiers). For instance, `master` is considered simple, `master-.*` would
-// not.
-var simpleBranchRegexp = regexp.MustCompile(`^[\w\-.]+$`)
-
-// makeBranchExplicit updates the provided branch to prevent wildcard matches to the given branch
-// if the branch value does not appear to contain an explicit regex pattern. I.e. 'master'
-// is turned into '^master$'.
-func makeBranchExplicit(branch string) string {
-	if !simpleBranchRegexp.MatchString(branch) {
+// exactlyBranch returns a regex string that matches exactly the given branch name: I.e. returns
+// '^master$' for 'master'. If the given branch name already looks like a regex, return it unchanged.
+func exactlyBranch(branch string) string {
+	if !jc.SimpleBranchRegexp.MatchString(branch) {
 		return branch
 	}
 	return fmt.Sprintf("^%s$", regexp.QuoteMeta(branch))
 }
 
+// featureBranch returns a regex string that matches feature branch prefixes for the given branch name:
+// I.e. returns '^master-' for 'master'. If the given branch name already looks like a regex,
+// return it unchanged.
+func featureBranch(branch string) string {
+	if !jc.SimpleBranchRegexp.MatchString(branch) {
+		return branch
+	}
+	return fmt.Sprintf("^%s-", regexp.QuoteMeta(branch))
+}
+
 // IsGenerated returns true if the job was generated using prowgen
 func IsGenerated(job prowconfig.JobBase) bool {
 	_, generated := job.Labels[prowJobLabelGenerated]

pkg/prowgen/testdata/zz_fixture_TestGenerateJobs_Promotion_configuration_causes_promote_job_with_unique_targets.yaml

@@ -58,7 +58,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - branch
+    - ^branch$
+    - ^branch-
     context: ci/prow/images
     decorate: true
     decoration_config:

pkg/prowgen/testdata/zz_fixture_TestGeneratePresubmitForTest_presubmit_for_a_test_in_a_variant_config.yaml

@@ -1,7 +1,8 @@
 agent: kubernetes
 always_run: true
 branches:
-- branch
+- ^branch$
+- ^branch-
 context: ci/prow/also-testname
 decorate: true
 decoration_config:

pkg/prowgen/testdata/zz_fixture_TestGeneratePresubmitForTest_presubmit_for_standard_test.yaml

@@ -1,7 +1,8 @@
 agent: kubernetes
 always_run: true
 branches:
-- branch
+- ^branch$
+- ^branch-
 context: ci/prow/testname
 decorate: true
 decoration_config:

pkg/prowgen/testdata/zz_fixture_TestGeneratePresubmitForTest_presubmit_with_job_release_specified.yaml

@@ -1,7 +1,8 @@
 agent: kubernetes
 always_run: true
 branches:
-- branch
+- ^branch$
+- ^branch-
 context: ci/prow/testname
 decorate: true
 decoration_config:

pkg/prowgen/testdata/zz_fixture_TestGeneratePresubmitForTest_presubmit_with_job_release_specified_and_clone.yaml

@@ -1,7 +1,8 @@
 agent: kubernetes
 always_run: true
 branches:
-- branch
+- ^branch$
+- ^branch-
 context: ci/prow/testname
 decorate: true
 labels:

pkg/rehearse/jobs.go

@@ -94,8 +94,17 @@ func NewCMClient(clusterConfig *rest.Config, namespace string, dry bool) (corecl
 // and we know that `\` is an invalid character in Git branch names, so any
 // that exist in the name have been placed there by regexp.QuoteMeta() and
 // can simply be removed as well.
+// Iterates over all branches and returns an empty string when no branch
+// is a simple branch name after the stripping
 func BranchFromRegexes(branches []string) string {
-	return strings.ReplaceAll(strings.TrimPrefix(strings.TrimSuffix(branches[0], "$"), "^"), "\\", "")
+	for i := range branches {
+		branch := strings.ReplaceAll(strings.TrimPrefix(strings.TrimSuffix(branches[i], "$"), "^"), "\\", "")
+		if branch != "" && jobconfig.SimpleBranchRegexp.MatchString(branch) {
+			return branch
+		}
+	}
+
+	return ""
 }
 
 func makeRehearsalPresubmit(source *prowconfig.Presubmit, repo string, prNumber int, refs *pjapi.Refs) (*prowconfig.Presubmit, error) {
@@ -196,11 +205,6 @@ func filterPresubmits(changedPresubmits map[string][]prowconfig.Presubmit, logge
 				continue
 			}
 
-			if len(job.Branches) != 1 {
-				jobLogger.Warn("cannot rehearse jobs that run over multiple branches")
-				continue
-			}
-
 			presubmits.Add(repo, job, config.GetSourceType(job.Labels))
 		}
 	}
@@ -440,10 +444,15 @@ func (jc *JobConfigurer) ConfigurePresubmitRehearsals(presubmits config.Presubmi
 			if len(splitOrgRepo) != 2 {
 				jobLogger.WithError(fmt.Errorf("failed to identify org and repo from string %s", orgrepo)).Warn("Failed to inline ci-operator-config into rehearsal presubmit job")
 			}
+			branch := BranchFromRegexes(job.Branches)
+			if branch == "" {
+				jobLogger.Warn("failed to extract a simple branch name for a presubmit")
+				continue
+			}
 			metadata := api.Metadata{
 				Org:     splitOrgRepo[0],
 				Repo:    splitOrgRepo[1],
-				Branch:  BranchFromRegexes(job.Branches),
+				Branch:  branch,
 				Variant: VariantFromLabels(job.Labels),
 			}
 			testname := metadata.TestNameFromJobName(job.Name, jobconfig.PresubmitPrefix)

test/integration/ci-operator-prowgen/output/jobs/private-org/duper/private-org-duper-master-presubmits.yaml

@@ -3,7 +3,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - master
+    - ^master$
+    - ^master-
     context: ci/prow/unit
     decorate: true
     decoration_config:

test/integration/ci-operator-prowgen/output/jobs/private/duper/private-duper-master-presubmits.yaml

@@ -3,7 +3,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - master
+    - ^master$
+    - ^master-
     context: ci/prow/e2e
     decorate: true
     decoration_config:
@@ -84,7 +85,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - master
+    - ^master$
+    - ^master-
     context: ci/prow/images
     decorate: true
     decoration_config:
@@ -140,7 +142,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - master
+    - ^master$
+    - ^master-
     context: ci/prow/unit
     decorate: true
     decoration_config:

test/integration/ci-operator-prowgen/output/jobs/subdir/repo/subdir-repo-master-presubmits.yaml

@@ -3,7 +3,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - master
+    - ^master$
+    - ^master-
     context: ci/prow/test
     decorate: true
     decoration_config:

test/integration/ci-operator-prowgen/output/jobs/super/duper/super-duper-master-presubmits.yaml

@@ -3,7 +3,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - master
+    - ^master$
+    - ^master-
     context: ci/prow/ci-index
     decorate: true
     decoration_config:
@@ -50,7 +51,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - master
+    - ^master$
+    - ^master-
     context: ci/prow/ci-index-my-bundle
     decorate: true
     decoration_config:
@@ -97,7 +99,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - master
+    - ^master$
+    - ^master-
     context: ci/prow/e2e
     decorate: true
     decoration_config:
@@ -170,7 +173,8 @@ presubmits:
   - agent: kubernetes
     always_run: false
     branches:
-    - master
+    - ^master$
+    - ^master-
     context: ci/prow/images
     decorate: true
     decoration_config:
@@ -232,7 +236,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - master
+    - ^master$
+    - ^master-
     context: ci/prow/lint
     decorate: true
     decoration_config:
@@ -279,7 +284,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - master
+    - ^master$
+    - ^master-
     context: ci/prow/steps
     decorate: true
     decoration_config:
@@ -333,7 +339,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - master
+    - ^master$
+    - ^master-
     context: ci/prow/unit
     decorate: true
     decoration_config:
@@ -380,7 +387,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - master
+    - ^master$
+    - ^master-
     context: ci/prow/variant-images
     decorate: true
     decoration_config:
@@ -431,7 +439,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - master
+    - ^master$
+    - ^master-
     context: ci/prow/variant-unit
     decorate: true
     decoration_config:

test/integration/ci-operator-prowgen/output/jobs/super/duper/super-duper-master-removed-promotion-presubmits.yaml

@@ -3,7 +3,8 @@ presubmits:
   - agent: kubernetes
     always_run: true
     branches:
-    - master-removed-promotion
+    - ^master-removed-promotion$
+    - ^master-removed-promotion-
     context: ci/prow/images
     decorate: true
     decoration_config: