Migrate SearchTest to PubPackageResolutionTest.

Change-Id: Ife51f8eb24bbb50e0f4bba4fa8358ec1f3a9368c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/176400
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>

pkg/analyzer/lib/src/test_utilities/find_element.dart

@@ -72,6 +72,30 @@ class FindElement extends _FindElementBase {
     return ImportFindElement(import);
   }
 
+  LabelElement label(String name) {
+    LabelElement result;
+
+    void updateResult(Element element) {
+      if (element is LabelElement && element.name == name) {
+        if (result != null) {
+          throw StateError('Not unique: $name');
+        }
+        result = element;
+      }
+    }
+
+    unit.accept(FunctionAstVisitor(
+      label: (node) {
+        updateResult(node.label.staticElement);
+      },
+    ));
+
+    if (result == null) {
+      throw StateError('Not found: $name');
+    }
+    return result;
+  }
+
   FunctionElement localFunction(String name) {
     FunctionElement result;
 

pkg/analyzer/lib/src/test_utilities/function_ast_visitor.dart

@@ -11,6 +11,7 @@ class FunctionAstVisitor extends RecursiveAstVisitor<void> {
   final void Function(FunctionDeclarationStatement)
       functionDeclarationStatement;
   final void Function(FunctionExpression, bool) functionExpression;
+  final void Function(Label) label;
   final void Function(SimpleIdentifier) simpleIdentifier;
   final void Function(VariableDeclaration) variableDeclaration;
 
@@ -18,6 +19,7 @@ class FunctionAstVisitor extends RecursiveAstVisitor<void> {
     this.declaredIdentifier,
     this.functionDeclarationStatement,
     this.functionExpression,
+    this.label,
     this.simpleIdentifier,
     this.variableDeclaration,
   });
@@ -48,6 +50,14 @@ class FunctionAstVisitor extends RecursiveAstVisitor<void> {
     super.visitFunctionExpression(node);
   }
 
+  @override
+  void visitLabel(Label node) {
+    if (label != null) {
+      label(node);
+    }
+    super.visitLabel(node);
+  }
+
   @override
   void visitSimpleIdentifier(SimpleIdentifier node) {
     if (simpleIdentifier != null) {

pkg/analyzer/test/src/dart/resolution/context_collection_resolution.dart

@@ -136,6 +136,10 @@ abstract class ContextResolutionTest
   Map<String, String> _declaredVariables = {};
   AnalysisContextCollection _analysisContextCollection;
 
+  /// If not `null`, [resolveFile] will use the context that corresponds
+  /// to this path, instead of the given path.
+  String pathForContextSelection;
+
   List<MockSdkLibrary> get additionalMockSdkLibraries => [];
 
   List<String> get collectionIncludedPaths;
@@ -204,7 +208,7 @@ abstract class ContextResolutionTest
 
   @override
   Future<ResolvedUnitResult> resolveFile(String path) {
-    var analysisContext = contextFor(path);
+    var analysisContext = contextFor(pathForContextSelection ?? path);
     var session = analysisContext.currentSession;
     return session.getResolvedUnit(path);
   }
@@ -259,6 +263,9 @@ class PubPackageResolutionTest extends ContextResolutionTest {
   @override
   List<String> get collectionIncludedPaths => [workspaceRootPath];
 
+  /// The path that is not in [workspaceRootPath], contains external packages.
+  String get packagesRootPath => '/packages';
+
   @override
   String get testFilePath => '$testPackageLibPath/test.dart';