Share sequence history construction

internal/engine/history_sequence_test.go

@@ -469,21 +469,18 @@ func TestSequenceHistoryReplaysCombinationEvidence(t *testing.T) {
 				t.Fatalf("combine diagnostics = %#v", diagnostics)
 			}
 
-			mode := sequenceHistoryMapped
-			if test.operation == sequenceModeReplace {
-				mode = sequenceHistoryReplace
-			}
-			length := 0
-			if mode == sequenceHistoryReplace {
-				length = len(combined.higherItems)
-			}
 			application := historyApplication{
 				layer: LayerOverlay,
 				value: higherRoot,
-				sequences: []sequenceHistoryContribution{{
-					path: Keys("records"), mode: mode, length: length,
-					items: combined.higherItems, replacements: combined.replacements,
-				}},
+				sequences: []sequenceHistoryContribution{
+					sequenceHistoryContributionForCombination(Keys("records"), test.operation, higher, combined),
+				},
+			}
+			if len(combined.higherItems) != 0 {
+				combined.higherItems[0].outputIndex++
+			}
+			if len(combined.replacements) != 0 {
+				combined.replacements[0].outputIndex++
 			}
 			application.sequencesByPath = indexSequenceHistoryContributions(application.sequences)
 			replayed := document.Clone(lowerRoot)