Adapt flow and promotion tests to make use of CFE testing framework.

This CL reworks the tests flow_analysis_test.dart and
type_promotion_test.dart to make use of the framework recently
introduced into pkg/front_end/lib/src/testing/id.dart.  The long term
goal is to move these tests into a common location so that they can
exercise both the front end and the analyzer.

Change-Id: Iad95065e995b0fe3c6e4990d2ea015215895743a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/108265
Reviewed-by: Johnni Winther <[email protected]>

Author: stereotype441

pkg/analyzer/lib/src/util/ast_data_extractor.dart

@@ -0,0 +1,105 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/visitor.dart';
+import 'package:front_end/src/testing/id.dart'
+    show ActualData, DataRegistry, Id, IdKind, NodeId;
+
+/// Abstract IR visitor for computing data corresponding to a node or element,
+/// and record it with a generic [Id]
+/// TODO(paulberry): if I try to extend GeneralizingAstVisitor<void>, the VM
+/// crashes.
+abstract class AstDataExtractor<T> extends GeneralizingAstVisitor<dynamic>
+    with DataRegistry<T> {
+  final Uri uri;
+
+  @override
+  final Map<Id, ActualData<T>> actualMap;
+
+  AstDataExtractor(this.uri, this.actualMap);
+
+  NodeId computeDefaultNodeId(AstNode node) =>
+      NodeId(_nodeOffset(node), IdKind.node);
+
+  void computeForExpression(Expression node, NodeId id) {
+    if (id == null) return;
+    T value = computeNodeValue(id, node);
+    registerValue(uri, node.offset, id, value, node);
+  }
+
+  void computeForFunctionBody(FunctionBody node, NodeId id) {
+    if (id == null) return;
+    T value = computeNodeValue(id, node);
+    registerValue(uri, node.offset, id, value, node);
+  }
+
+  void computeForStatement(Statement node, NodeId id) {
+    if (id == null) return;
+    T value = computeNodeValue(id, node);
+    registerValue(uri, node.offset, id, value, node);
+  }
+
+  /// Implement this to compute the data corresponding to [node].
+  ///
+  /// If `null` is returned, [node] has no associated data.
+  T computeNodeValue(Id id, AstNode node);
+
+  NodeId createFunctionBodyId(FunctionBody node) =>
+      NodeId(_nodeOffset(node), IdKind.functionBody);
+
+  NodeId createStatementId(Statement node) =>
+      NodeId(_nodeOffset(node), IdKind.statement);
+
+  @override
+  void fail(String message) {
+    throw _Failure(message);
+  }
+
+  @override
+  void report(Uri uri, int offset, String message) {
+    // TODO(paulberry): find a way to print the error more nicely.
+    print('$uri:$offset: $message');
+  }
+
+  void run(CompilationUnit unit) {
+    unit.accept(this);
+  }
+
+  @override
+  visitExpression(Expression node) {
+    computeForExpression(node, computeDefaultNodeId(node));
+    super.visitExpression(node);
+  }
+
+  @override
+  visitFunctionBody(FunctionBody node) {
+    computeForFunctionBody(node, createFunctionBodyId(node));
+    super.visitFunctionBody(node);
+  }
+
+  @override
+  visitStatement(Statement node) {
+    computeForStatement(node, createStatementId(node));
+    super.visitStatement(node);
+  }
+
+  int _nodeOffset(AstNode node) {
+    var offset = node.offset;
+    assert(offset != null && offset >= 0,
+        "No fileOffset on $node (${node.runtimeType})");
+    return offset;
+  }
+}
+
+class _Failure implements Exception {
+  final message;
+
+  _Failure([this.message]);
+
+  String toString() {
+    if (message == null) return "Exception";
+    return "Exception: $message";
+  }
+}