Add sanity checks for NNBD state in migration.

Also adds some ability for the migration tool to abort itself on
a few known-fatal errors and armor-plates dartdev tests against
CWD problems.

Bug: https://github.com/dart-lang/sdk/issues/40329
Change-Id: I1cfa2c9dcc7815eed075ecb38c63a74c75889002
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/139282
Reviewed-by: Paul Berry <paulberry@google.com>
Commit-Queue: Janice Collins <jcollins@google.com>

pkg/dartdev/test/commands/migrate_test.dart

@@ -7,6 +7,10 @@ import 'package:test/test.dart';
 
 import '../utils.dart';
 
+// TODO(jcollins-g): Set to true and/or remove when when NNBD is enabled in the
+//  SDK running this test.
+bool _nnbdIsEnabled = false;
+
 void main() {
   group('migrate', defineMigrateTests);
 }
@@ -30,24 +34,34 @@ void defineMigrateTests() {
 
   test('directory implicit', () {
     p = project(mainSrc: 'int get foo => 1;\n');
-    var result =
-        p.runSync('migrate', ['--no-web-preview'], workingDir: p.dirPath);
-    expect(result.exitCode, 0);
-    expect(result.stderr, isEmpty);
+    var result = p.runSync(
+        'migrate',
+        [
+          '--no-web-preview',
+          '--server-path=${p.absolutePathToAnalysisServerFile}'
+        ],
+        workingDir: p.dirPath);
+    expect(result.exitCode, _nnbdIsEnabled ? 0 : 2);
+    expect(result.stderr, _nnbdIsEnabled ? isEmpty : isNotEmpty);
     expect(result.stdout, contains('Generating migration suggestions'));
   });
 
   test('directory explicit', () {
     p = project(mainSrc: 'int get foo => 1;\n');
-    var result = p.runSync('migrate', ['--no-web-preview', p.dirPath]);
-    expect(result.exitCode, 0);
-    expect(result.stderr, isEmpty);
+    var result = p.runSync('migrate', [
+      '--no-web-preview',
+      '--server-path=${p.absolutePathToAnalysisServerFile}',
+      p.dirPath
+    ]);
+    expect(result.exitCode, _nnbdIsEnabled ? 0 : 2);
+    expect(result.stderr, _nnbdIsEnabled ? isEmpty : isNotEmpty);
     expect(result.stdout, contains('Generating migration suggestions'));
   });
 
   test('bad directory', () {
     p = project(mainSrc: 'int get foo => 1;\n');
-    var result = p.runSync('migrate', ['foo_bar_dir']);
+    var result = p.runSync('migrate',
+        ['--server-path=${p.absolutePathToAnalysisServerFile}', 'foo_bar_dir']);
     expect(result.exitCode, 64);
     expect(result.stderr,
         contains('not found; please provide a path to a package or directory'));

pkg/dartdev/test/utils.dart

@@ -63,18 +63,34 @@ class TestProject {
     );
   }
 
-  /// The path relative from `Directory.current.path` to `dartdev.dart` is
-  /// different when executing these tests locally versus on the Dart
-  /// buildbots, this if-else captures this change and branches for each case.
-  String get absolutePathToDartdevFile {
-    var dartdevFilePathOnBots = path.absolute(path.join(
-        Directory.current.path, 'pkg', 'dartdev', 'bin', 'dartdev.dart'));
-    if (File(dartdevFilePathOnBots).existsSync()) {
-      return dartdevFilePathOnBots;
-    } else {
-      return path
-          .absolute(path.join(Directory.current.path, 'bin', 'dartdev.dart'));
+  String _sdkRootPath;
+
+  /// Return the root of the SDK.
+  String get sdkRootPath {
+    if (_sdkRootPath == null) {
+      // Assumes the script importing this one is somewhere under the SDK.
+      String current = path.canonicalize(Platform.script.toFilePath());
+      do {
+        String tryDir = path.dirname(current);
+        if (File(path.join(tryDir, 'pkg', 'dartdev', 'bin', 'dartdev.dart'))
+            .existsSync()) {
+          _sdkRootPath = tryDir;
+          return _sdkRootPath;
+        }
+        current = tryDir;
+      } while (path.dirname(current) != current);
+      throw StateError('can not find SDK repository root');
     }
+    return _sdkRootPath;
+  }
+
+  String get absolutePathToDartdevFile {
+    return path.join(sdkRootPath, 'pkg', 'dartdev', 'bin', 'dartdev.dart');
+  }
+
+  String get absolutePathToAnalysisServerFile {
+    return path.join(
+        sdkRootPath, 'pkg', 'analysis_server', 'bin', 'server.dart');
   }
 
   File findFile(String name) {