Disable Matrix Validation for non Matrix Pipelines

This disables the Matrix Validation for Results in non Matrixed Pipelines.
This ensure we don't encounter any crash or such for these pipelines like
did at issue tektoncd#8086

pkg/apis/pipeline/v1/pipeline_validation.go

@@ -779,10 +779,16 @@ func validateGraph(tasks []PipelineTask) (errs *apis.FieldError) {
 }
 
 func validateMatrix(ctx context.Context, tasks []PipelineTask) (errs *apis.FieldError) {
+	hasMatrix := false
 	for idx, task := range tasks {
-		errs = errs.Also(task.validateMatrix(ctx).ViaIndex(idx))
+		if task.IsMatrixed() {
+			errs = errs.Also(task.validateMatrix(ctx).ViaIndex(idx))
+			hasMatrix = true
+		}
+	}
+	if hasMatrix {
+		errs = errs.Also(validateTaskResultsFromMatrixedPipelineTasksConsumed(tasks))
 	}
-	errs = errs.Also(validateTaskResultsFromMatrixedPipelineTasksConsumed(tasks))
 	return errs
 }
 
@@ -812,6 +818,9 @@ func validateMatrixedPipelineTaskConsumed(expressions []string, taskMapping map[
 	for _, expression := range expressions {
 		// ie. "tasks.<pipelineTaskName>.results.<resultName>[*]"
 		subExpressions := strings.Split(expression, ".")
+		if len(subExpressions) < 2 {
+			continue
+		}
 		pipelineTask := subExpressions[1] // pipelineTaskName
 		taskConsumed := taskMapping[pipelineTask]
 		if taskConsumed.IsMatrixed() {

test/e2e-tests-upgrade.sh

@@ -82,14 +82,30 @@ header "Create resources at previous release version"
 kubectl create namespace upgrade
 trap "kubectl delete namespace upgrade" EXIT
 kubectl create -f ./test/upgrade/simpleResources.yaml || fail_test
+kubectl create -f ./test/upgrade/resultRefResources.yaml || fail_test
 
 # Upgrade to the current release.
 header "Upgrade to the current release of Tekton pipeline"
 install_pipeline_crd
 
+initRestartCount=$(kubectl get pods -o=jsonpath='{.items[?(@.metadata.labels.app=="tekton-pipelines-controller")].status.containerStatuses[0].restartCount}' -n ${SYSTEM_NAMESPACE})
+
 # Create runs from the Task and Pipeline resources created at the previous release version
 header "Creating TaskRuns and PipelineRuns referencing existing Tasks and Pipelines"
 kubectl create -f ./test/upgrade/simpleRuns.yaml || fail_test
+kubectl create -f ./test/upgrade/resultRefRuns.yaml || fail_test
+
+for i in $(kc get pr -o=custom-columns=NAMENAME:.metadata.name --no-headers);
+      do kubectl wait --for=jsonpath='{.status.conditions[0].reason}'=Succeeded pipelinerun $i;
+done
+
+curRestartCount=$(kubectl get pods -o=jsonpath='{.items[?(@.metadata.labels.app=="tekton-pipelines-controller")].status.containerStatuses[0].restartCount}' -n ${SYSTEM_NAMESPACE})
+
+if [ ${initRestartCount} -ne ${curRestartCount} ];
+   echo "controller restarted"
+   then fail_test;
+fi
+
 
 # Run the post-integration tests. We do not need to install the resources again, since
 # they are installed before the upgrade. We verify if they still work, after going through

test/upgrade/resultRefResources.yaml

@@ -0,0 +1,64 @@
+apiVersion: tekton.dev/v1
+kind: Task
+metadata:
+  name: add-task
+spec:
+  params:
+    - name: first
+      description: the first operand
+    - name: second
+      description: the second operand
+  results:
+    - name: sum
+      description: the sum of the first and second operand
+  steps:
+    - name: add
+      image: alpine
+      env:
+        - name: OP1
+          value: $(params.first)
+        - name: OP2
+          value: $(params.second)
+      command: ["/bin/sh", "-c"]
+      args:
+        - echo -n $((${OP1}+${OP2})) | tee $(results.sum.path);
+---
+apiVersion: tekton.dev/v1
+kind: Pipeline
+metadata:
+  name: sum-three-pipeline
+spec:
+  params:
+    - name: first
+      description: the first operand
+    - name: second
+      description: the second operand
+    - name: third
+      description: the third operand
+  tasks:
+    - name: first-add
+      taskRef:
+        name: add-task
+      params:
+        - name: first
+          value: $(params.first)
+        - name: second
+          value: $(params.second)
+    - name: second-add
+      taskRef:
+        name: add-task
+      params:
+        - name: first
+          value: $(tasks.first-add.results.sum)
+        - name: second
+          value: $(tasks.first-add.results.sum) - $(sum)
+  results:
+    - name: sum
+      description: the sum of all three operands
+      value: $(tasks.second-add.results.sum)
+    - name: partial-sum
+      description: the sum of first two operands
+      value: $(tasks.first-add.results.sum)
+    - name: all-sum
+      description: the sum of everything
+      value: $(tasks.second-add.results.sum)-$(tasks.first-add.results.sum)

test/upgrade/resultRefRuns.yaml

@@ -0,0 +1,14 @@
+apiVersion: tekton.dev/v1
+kind: PipelineRun
+metadata:
+  name: resultRefRun
+spec:
+  pipelineRef:
+    name: sum-three-pipeline
+  params:
+    - name: first
+      value: "2"
+    - name: second
+      value: "10"
+    - name: third
+      value: "10"