cleanup,test: differenciate between unresolved parameters and circula…

…r dependencies

pkg/reconciler/taskrun/resources/apply.go

@@ -131,6 +131,9 @@ func applyStepActionParameters(step *v1.Step, spec *v1.TaskSpec, tr *v1.TaskRun,
 	// process parameters until no more can be resolved
 	for len(paramsNeedingResolution) > 0 {
 		paramWasResolved := false
+		// track unresolved params and their references
+		unresolvedParams := make(map[string][]string)
+
 		for paramName := range paramsNeedingResolution {
 			canResolveParam := true
 			for _, referencedParam := range paramReferenceMap[paramName] {
@@ -144,6 +147,7 @@ func applyStepActionParameters(step *v1.Step, spec *v1.TaskSpec, tr *v1.TaskRun,
 				}
 				if !isReferenceResolved {
 					canResolveParam = false
+					unresolvedParams[paramName] = append(unresolvedParams[paramName], referencedParam)
 					break
 				}
 			}
@@ -180,9 +184,26 @@ func applyStepActionParameters(step *v1.Step, spec *v1.TaskSpec, tr *v1.TaskRun,
 			}
 		}
 
-		// circular dependency detected
+		// unresolvable parameters or circular dependencies
 		if !paramWasResolved {
-			return nil, fmt.Errorf("circular dependency detected in parameter references")
+			// check parameter references to a non-existent parameter
+			for param, unresolvedRefs := range unresolvedParams {
+				// check referenced parameters in defaults
+				for _, ref := range unresolvedRefs {
+					exists := false
+					for _, p := range defaults {
+						if p.Name == ref {
+							exists = true
+							break
+						}
+					}
+					if !exists {
+						return nil, fmt.Errorf("parameter %q references non-existent parameter %q", param, ref)
+					}
+				}
+				// parameters exist but can't be resolved hence it's a circular dependency
+				return nil, fmt.Errorf("circular dependency detected in parameter references")
+			}
 		}
 	}
 

pkg/reconciler/taskrun/resources/taskspec_test.go

@@ -1595,6 +1595,42 @@ func TestGetStepActionsData_Error(t *testing.T) {
 		stepAction    *v1beta1.StepAction
 		expectedError error
 	}{{
+		name: "unresolvable parameter reference",
+		tr: &v1.TaskRun{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      "mytaskrun",
+				Namespace: "default",
+			},
+			Spec: v1.TaskRunSpec{
+				TaskSpec: &v1.TaskSpec{
+					Steps: []v1.Step{{
+						Ref: &v1.Ref{
+							Name: "stepAction",
+						},
+					}},
+				},
+			},
+		},
+		stepAction: &v1beta1.StepAction{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      "stepAction",
+				Namespace: "default",
+			},
+			Spec: v1beta1.StepActionSpec{
+				Image: "myimage",
+				Args:  []string{"$(params.param1)"},
+				Params: v1.ParamSpecs{{
+					Name: "param1",
+					Type: v1.ParamTypeString,
+					Default: &v1.ParamValue{
+						Type:      v1.ParamTypeString,
+						StringVal: "$(params.nonexistent)",
+					},
+				}},
+			},
+		},
+		expectedError: errors.New(`parameter "param1" references non-existent parameter "nonexistent"`),
+	}, {
 		name: "circular dependency in params",
 		tr: &v1.TaskRun{
 			ObjectMeta: metav1.ObjectMeta{