Index inheritance history lookups

internal/engine/inheritance_history_test.go

@@ -2,6 +2,7 @@ package engine
 
 import (
 	"bytes"
+	"reflect"
 	"strings"
 	"testing"
 
@@ -311,6 +312,51 @@ func TestInheritanceHistoryRetainsControlsAndDisplacedPaths(t *testing.T) {
 	}
 }
 
+func TestIndexedInheritanceHistoryMatchesOperationScan(t *testing.T) {
+	inspection, _ := inheritanceInspectionForTest(t,
+		parseCompositionDocument(t, "source-1", "parent: {branch: {detail: inherited, retained: present}}\n"),
+		parseCompositionDocument(t, "source-2", "child: {extends: parent, branch: replaced}\n"),
+		parseCompositionDocument(t, "source-3", "sibling: {extends: parent}\n"))
+	metadata := inspection.Metadata()
+	if len(metadata.inheritance) < 4 {
+		t.Fatalf("inheritance operations = %d, want multiple control and transfer scopes", len(metadata.inheritance))
+	}
+	queries := []Path{
+		Keys("child"),
+		Keys("child", inheritanceKey),
+		Keys("child", "branch", "detail"),
+		Keys("child", "branch"),
+		Keys("sibling", "branch", "detail"),
+		Path{},
+	}
+	for _, path := range queries {
+		if !metadata.hasHistoricalPath(path) {
+			continue
+		}
+		stored := metadata.history[path.String()]
+		want := historyWithInheritance(path, stored, metadata.inheritance)
+		if got := metadata.History(path); !reflect.DeepEqual(got, want) {
+			t.Errorf("indexed history for %s differs from operation scan:\n got: %#v\nwant: %#v", path, got, want)
+		}
+		unprepared := Metadata{history: metadata.history, historicalPaths: metadata.historicalPaths, inheritance: metadata.inheritance}
+		if got := unprepared.History(path); !reflect.DeepEqual(got, want) {
+			t.Errorf("unprepared history for %s differs from operation scan:\n got: %#v\nwant: %#v", path, got, want)
+		}
+	}
+
+	removed := Keys("child", "branch", "detail")
+	first := metadata.History(removed)
+	if len(first) == 0 || len(first[0].Path.segments) == 0 {
+		t.Fatalf("removed-path history = %#v", first)
+	}
+	first[0].Path.segments[0].key = "mutated"
+	second := cloneMetadata(metadata).History(removed)
+	want := historyWithInheritance(removed, metadata.history[removed.String()], metadata.inheritance)
+	if !reflect.DeepEqual(second, want) {
+		t.Fatalf("returned history mutation affected a repeated or cloned query:\n got: %#v\nwant: %#v", second, want)
+	}
+}
+
 func TestInheritanceHistoryPrecedesApplicationResolution(t *testing.T) {
 	inspection, _ := inheritanceInspectionForTest(t,
 		parseCompositionDocument(t, "source-1", "parent: {value: original}\nchild: {extends: parent}\n"))