Test that augmentations are listed in the depth-first pre-order.

Change-Id: I7ade7b101c3c7895c1e8a68ca336ac83fa2b1348
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/312341
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/test/src/summary/element_text.dart

@@ -133,6 +133,7 @@ class ElementTextConfiguration {
   bool withExportScope = false;
   bool withFunctionTypeParameters = false;
   bool withImports = true;
+  bool withLibraryAugmentations = false;
   bool withMetadata = true;
   bool withNonSynthetic = false;
   bool withPropertyLinking = false;
@@ -262,7 +263,7 @@ class _ElementWriter {
     return components.join(';');
   }
 
-  void _writeAugmentationElement(LibraryAugmentationElement e) {
+  void _writeAugmentationElement(LibraryAugmentationElementImpl e) {
     _writeLibraryOrAugmentationElement(e);
   }
 
@@ -274,7 +275,7 @@ class _ElementWriter {
 
     _sink.withIndent(() {
       _writeMetadata(e);
-      if (uri is DirectiveUriWithAugmentation) {
+      if (uri is DirectiveUriWithAugmentationImpl) {
         _writeAugmentationElement(uri.augmentation);
       }
     });
@@ -644,7 +645,22 @@ class _ElementWriter {
     }
   }
 
-  void _writeLibraryOrAugmentationElement(LibraryOrAugmentationElement e) {
+  void _writeLibraryAugmentations(LibraryElementImpl e) {
+    if (configuration.withLibraryAugmentations) {
+      final augmentations = e.augmentations;
+      if (augmentations.isNotEmpty) {
+        _sink.writelnWithIndent('augmentations');
+        _sink.withIndent(() {
+          for (final element in augmentations) {
+            _sink.writeIndent();
+            _elementPrinter.writeElement0(element);
+          }
+        });
+      }
+    }
+  }
+
+  void _writeLibraryOrAugmentationElement(LibraryOrAugmentationElementImpl e) {
     _writeDocumentation(e);
     _writeMetadata(e);
     _writeSinceSdkVersion(e);
@@ -665,6 +681,10 @@ class _ElementWriter {
     _sink.withIndent(() {
       _writeUnitElement(e.definingCompilationUnit);
     });
+
+    if (e is LibraryElementImpl) {
+      _writeLibraryAugmentations(e);
+    }
   }
 
   void _writeMetadata(Element element) {

pkg/analyzer/test/src/summary/elements_test.dart

@@ -29073,6 +29073,48 @@ library
     expect(augmentation.enclosingElement2, same(library));
   }
 
+  test_library_augmentationImports_depthFirst() async {
+    newFile('$testPackageLibPath/a.dart', r'''
+library augment 'test.dart';
+import augment 'b.dart';
+''');
+
+    newFile('$testPackageLibPath/b.dart', r'''
+library augment 'a.dart';
+''');
+
+    newFile('$testPackageLibPath/c.dart', r'''
+library augment 'test.dart';
+''');
+
+    final library = await buildLibrary(r'''
+import augment 'a.dart';
+import augment 'c.dart';
+''');
+
+    configuration.withLibraryAugmentations = true;
+    checkElementText(library, r'''
+library
+  augmentationImports
+    package:test/a.dart
+      augmentationImports
+        package:test/b.dart
+          definingUnit
+      definingUnit
+    package:test/c.dart
+      definingUnit
+  definingUnit
+  augmentations
+    self::@augmentation::package:test/a.dart
+    self::@augmentation::package:test/b.dart
+    self::@augmentation::package:test/c.dart
+''');
+
+    final import_0 = library.augmentationImports[0];
+    final augmentation = import_0.importedAugmentation!;
+    expect(augmentation.enclosingElement2, same(library));
+  }
+
   test_library_augmentationImports_noRelativeUriStr() async {
     final library = await buildLibrary(r'''
 import augment '${'foo'}.dart';

pkg/analyzer/test/util/element_printer.dart

@@ -69,7 +69,11 @@ class ElementPrinter {
 
   void writeElement(String name, Element? element) {
     _sink.writeWithIndent('$name: ');
+    writeElement0(element);
+  }
 
+  /// TODO(scheglov) rename [writeElement] to `writeNamedElement`, and this.
+  void writeElement0(Element? element) {
     switch (element) {
       case null:
         _sink.writeln('<null>');