Combine final metadata traversal

internal/engine/metadata_test.go

@@ -47,6 +47,60 @@ func TestMetadataHistoricalPaths(t *testing.T) {
 	}
 }
 
+func TestMetadataPathIndexesOwnIndependentSegments(t *testing.T) {
+	t.Parallel()
+
+	final := parseDocumentForDecode(t, "service: {workers: [1]}\n")
+	var metadata Metadata
+	finalizeMetadataPaths(&metadata, final, nil)
+	pointer := "/service/workers/0"
+	effective := metadata.effectivePaths[pointer]
+	historical := metadata.historicalPaths[pointer]
+	if effective.String() != pointer || len(historical) != 1 || historical[0].String() != pointer {
+		t.Fatalf("path indexes = %#v, %#v", effective, historical)
+	}
+
+	effective.segments[0].key = "effective"
+	if historical[0].String() != pointer {
+		t.Fatal("effective path mutation changed historical path")
+	}
+	historical[0].segments[2].index = 1
+	if effective.String() != "/effective/workers/0" {
+		t.Fatal("historical path mutation changed effective path")
+	}
+}
+
+func TestMetadataPathIndexesRetainDistinctHistoricalShapes(t *testing.T) {
+	t.Parallel()
+
+	final := parseDocumentForDecode(t, "shape: [replacement]\n")
+	earlier := parseDocumentForDecode(t, "shape: {'0': base}\n")
+	var metadata Metadata
+	// Repeated trees must not add duplicate shapes to the historical index.
+	finalizeMetadataPaths(&metadata, final, nil, earlier, earlier, final)
+	keyPath := Keys("shape", "0")
+	indexPath := Keys("shape").Index(0)
+	pointer := indexPath.String()
+	if !reflect.DeepEqual(metadata.effectivePaths[pointer], indexPath) {
+		t.Fatal("effective index does not reflect the final sequence")
+	}
+	historical := metadata.historicalPaths[pointer]
+	if len(historical) != 2 {
+		t.Fatalf("historical shapes = %#v, want one key and one index", historical)
+	}
+	for _, want := range []Path{keyPath, indexPath} {
+		found := false
+		for _, path := range historical {
+			if reflect.DeepEqual(path, want) {
+				found = true
+			}
+		}
+		if !found || !metadata.hasHistoricalPath(want) {
+			t.Fatalf("historical index lost shape %#v", want)
+		}
+	}
+}
+
 func TestHistoricalPathsExposeHiddenBaseOwnershipWithoutResolvingBaseSecrets(t *testing.T) {
 	t.Setenv("CONFIGKIT_HISTORY_UNUSED_PROD_KEY", "")
 	t.Setenv("CONFIGKIT_HISTORY_TEST_KEY", "synthetic-test-key")