Get Names of TaskRuns from ChildReferences only

In tektoncd/community#736, we decided that
`Matrix` will use `ChildReferences` only. Therefore, it is unnecessary
to check the `TaskRuns` field of `PipelineRun` status when getting the
names of `TaskRuns` for matrixed `PipelineTasks`.

Related PR: tektoncd#5019

pkg/reconciler/pipelinerun/resources/pipelinerunresolution.go

@@ -522,7 +522,7 @@ func ResolvePipelineTask(
 		}
 		rpt.Run = run
 	case rpt.IsMatrixed():
-		rpt.TaskRunNames = GetNamesOfTaskRuns(pipelineRun.Status.TaskRuns, pipelineRun.Status.ChildReferences, pipelineTask.Name, pipelineRun.Name, pipelineTask.GetMatrixCombinationsCount())
+		rpt.TaskRunNames = GetNamesOfTaskRuns(pipelineRun.Status.ChildReferences, pipelineTask.Name, pipelineRun.Name, pipelineTask.GetMatrixCombinationsCount())
 		for _, taskRunName := range rpt.TaskRunNames {
 			if err := rpt.resolvePipelineRunTaskWithTaskRun(ctx, taskRunName, getTask, getTaskRun, pipelineTask, providedResources); err != nil {
 				return nil, err
@@ -648,12 +648,8 @@ func GetTaskRunName(taskRunsStatus map[string]*v1beta1.PipelineRunTaskRunStatus,
 }
 
 // GetNamesOfTaskRuns should return unique names for `TaskRuns` if one has not already been defined, and the existing one otherwise.
-func GetNamesOfTaskRuns(taskRunsStatus map[string]*v1beta1.PipelineRunTaskRunStatus, childRefs []v1beta1.ChildStatusReference, ptName, prName string, combinationCount int) []string {
-	var taskRunNames []string
-	if taskRunNames = getTaskRunNamesFromChildRefs(childRefs, ptName); taskRunNames != nil {
-		return taskRunNames
-	}
-	if taskRunNames = getTaskRunNamesFromTaskRunsStatus(taskRunsStatus, ptName); taskRunNames != nil {
+func GetNamesOfTaskRuns(childRefs []v1beta1.ChildStatusReference, ptName, prName string, combinationCount int) []string {
+	if taskRunNames := getTaskRunNamesFromChildRefs(childRefs, ptName); taskRunNames != nil {
 		return taskRunNames
 	}
 	return getNewTaskRunNames(ptName, prName, combinationCount)
@@ -669,16 +665,6 @@ func getTaskRunNamesFromChildRefs(childRefs []v1beta1.ChildStatusReference, ptNa
 	return taskRunNames
 }
 
-func getTaskRunNamesFromTaskRunsStatus(taskRunsStatus map[string]*v1beta1.PipelineRunTaskRunStatus, ptName string) []string {
-	var taskRunNames []string
-	for k, v := range taskRunsStatus {
-		if v.PipelineTaskName == ptName {
-			taskRunNames = append(taskRunNames, k)
-		}
-	}
-	return taskRunNames
-}
-
 func getNewTaskRunNames(ptName, prName string, combinationCount int) []string {
 	var taskRunNames []string
 	for i := 0; i < combinationCount; i++ {

pkg/reconciler/pipelinerun/resources/pipelinerunresolution_test.go

@@ -2831,15 +2831,6 @@ func TestGetTaskRunName(t *testing.T) {
 
 func TestGetNamesOfTaskRuns(t *testing.T) {
 	prName := "mypipelinerun"
-	taskRunsStatus := map[string]*v1beta1.PipelineRunTaskRunStatus{
-		"mypipelinerun-mytask-0": {
-			PipelineTaskName: "mytask",
-		},
-		"mypipelinerun-mytask-1": {
-			PipelineTaskName: "mytask",
-		},
-	}
-
 	childRefs := []v1beta1.ChildStatusReference{{
 		TypeMeta:         runtime.TypeMeta{Kind: "TaskRun"},
 		Name:             "mypipelinerun-mytask-0",
@@ -2892,12 +2883,7 @@ func TestGetNamesOfTaskRuns(t *testing.T) {
 			if tc.prName != "" {
 				testPrName = tc.prName
 			}
-			namesOfTaskRunsFromTaskRunsStatus := GetNamesOfTaskRuns(taskRunsStatus, nil, tc.ptName, testPrName, 2)
-			sort.Strings(namesOfTaskRunsFromTaskRunsStatus)
-			if d := cmp.Diff(tc.wantTrNames, namesOfTaskRunsFromTaskRunsStatus); d != "" {
-				t.Errorf("GetTaskRunName: %s", diff.PrintWantGot(d))
-			}
-			namesOfTaskRunsFromChildRefs := GetNamesOfTaskRuns(nil, childRefs, tc.ptName, testPrName, 2)
+			namesOfTaskRunsFromChildRefs := GetNamesOfTaskRuns(childRefs, tc.ptName, testPrName, 2)
 			sort.Strings(namesOfTaskRunsFromChildRefs)
 			if d := cmp.Diff(tc.wantTrNames, namesOfTaskRunsFromChildRefs); d != "" {
 				t.Errorf("GetTaskRunName: %s", diff.PrintWantGot(d))