Resolved result ref order can affect unit test outcome

Test TestTaskParamResolver_ResolveResultRefs performs a diff on a slice
of resolved result references. Unfortunately the ordering of this slice
is not guaranteed so sometimes the test fails.

This PR updates the unit test to check each entry appears as expected in
the tt.want slice (confirming also that the lengths of the slices
match). Also adds a small helper func to format the resolved result refs
for printing in the event that they don't match.

pkg/reconciler/pipelinerun/resources/resultrefresolution_test.go

@@ -1,6 +1,8 @@
 package resources
 
 import (
+	"fmt"
+	"strings"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
@@ -256,16 +258,34 @@ func TestTaskParamResolver_ResolveResultRefs(t *testing.T) {
 			t.Logf("test name: %s\n", tt.name)
 			got, err := extractResultRefsFromParam(tt.fields.pipelineRunState, tt.args.param)
 			if (err != nil) != tt.wantErr {
-				t.Errorf("ResolveResultRef() error = %v, wantErr %v", err, tt.wantErr)
-				return
+				t.Fatalf("ResolveResultRef() error = %v, wantErr %v", err, tt.wantErr)
 			}
-			if d := cmp.Diff(tt.want, got); d != "" {
-				t.Fatalf("ResolveResultRef  -want, +got: %v", d)
+			if len(tt.want) != len(got) {
+				t.Fatalf("incorrect number of refs, want %d, got %d", len(tt.want), len(got))
+			}
+			for _, rGot := range got {
+				foundMatch := false
+				for _, rWant := range tt.want {
+					if d := cmp.Diff(rGot, rWant); d == "" {
+						foundMatch = true
+					}
+				}
+				if !foundMatch {
+					t.Fatalf("Expected resolved refs:\n%s\n\nbut received:\n%s\n", resolvedSliceAsString(tt.want), resolvedSliceAsString(got))
+				}
 			}
 		})
 	}
 }
 
+func resolvedSliceAsString(rs []*ResolvedResultRef) string {
+	var s []string
+	for _, r := range rs {
+		s = append(s, fmt.Sprintf("%#v", *r))
+	}
+	return fmt.Sprintf("[\n%s\n]", strings.Join(s, ",\n"))
+}
+
 func TestResolveResultRefs(t *testing.T) {
 	type args struct {
 		pipelineRunState PipelineRunState