[dds] Add tests for DAP exception behaviour

Change-Id: I524a7bdebd0c4f572db67550cd42f4ba5118cfc3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/209640
Reviewed-by: Ben Konyi <bkonyi@google.com>
Commit-Queue: Ben Konyi <bkonyi@google.com>

pkg/dds/test/dap/integration/debug_exceptions_test.dart

@@ -0,0 +1,75 @@
+// Copyright (c) 2021, 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:test/test.dart';
+
+import 'test_client.dart';
+import 'test_scripts.dart';
+import 'test_support.dart';
+
+main() {
+  group('debug mode', () {
+    late DapTestSession dap;
+    setUp(() async {
+      dap = await DapTestSession.setUp();
+    });
+    tearDown(() => dap.tearDown());
+
+    test('does not pause on exceptions if mode not set', () async {
+      final client = dap.client;
+      final testFile = dap.createTestFile(simpleThrowingProgram);
+
+      // Run the app and expect it to complete (it should not pause).
+      final outputEvents = await client.collectOutput(file: testFile);
+
+      // Expect error info printed to stderr.
+      final output = outputEvents
+          .where((e) => e.category == 'stderr')
+          .map((e) => e.output)
+          .join();
+      expectLinesStartWith(output, [
+        'Unhandled exception:',
+        'error',
+      ]);
+    });
+
+    test('pauses on uncaught exceptions when mode=Unhandled', () async {
+      final client = dap.client;
+      final testFile = dap.createTestFile(simpleThrowingProgram);
+
+      // Run and expect to pause on an exception.
+      await client.pauseOnException(
+        testFile,
+        exceptionPauseMode: 'Unhandled',
+      );
+    });
+
+    test('does not pauses on caught exceptions when mode=Unhandled', () async {
+      final client = dap.client;
+      final testFile = dap.createTestFile(simpleCaughtErrorProgram);
+
+      // Run the app and expect it to complete (it should not pause).
+      final outputEvents = await client.collectOutput(file: testFile);
+
+      // Expect error info printed to stderr.
+      final output = outputEvents
+          .where((e) => e.category == 'stdout')
+          .map((e) => e.output)
+          .join();
+      expectLines(output, ['Caught!']);
+    });
+
+    test('pauses on caught exceptions when mode=All', () async {
+      final client = dap.client;
+      final testFile = dap.createTestFile(simpleCaughtErrorProgram);
+
+      // Run and expect to pause on an exception.
+      await client.pauseOnException(
+        testFile,
+        exceptionPauseMode: 'All',
+      );
+    });
+    // These tests can be slow due to starting up the external server process.
+  }, timeout: Timeout.none);
+}

pkg/dds/test/dap/integration/test_client.dart

@@ -409,6 +409,31 @@ extension DapTestClientExtension on DapTestClient {
     return stop;
   }
 
+  /// Sets the exception pause mode to [pauseMode] and expects to pause after
+  /// running the script.
+  ///
+  /// Launch options can be customised by passing a custom [launch] function that
+  /// will be used instead of calling `launch(file.path)`.
+  Future<StoppedEventBody> pauseOnException(
+    File file, {
+    String? exceptionPauseMode, // All, Unhandled, None
+    Future<Response> Function()? launch,
+  }) async {
+    final stop = expectStop('exception', file: file);
+
+    await Future.wait([
+      initialize(),
+      sendRequest(
+        SetExceptionBreakpointsArguments(
+          filters: [if (exceptionPauseMode != null) exceptionPauseMode],
+        ),
+      ),
+      launch?.call() ?? this.launch(file.path),
+    ], eagerError: true);
+
+    return stop;
+  }
+
   /// Returns whether DDS is available for the VM Service the debug adapter
   /// is connected to.
   Future<bool> get ddsAvailable async {

pkg/dds/test/dap/integration/test_scripts.dart

@@ -15,3 +15,21 @@ const simpleBreakpointProgram = r'''
     print('Hello!'); // BREAKPOINT
   }
 ''';
+
+/// A simple Dart script that throws an error and catches it in user code.
+const simpleCaughtErrorProgram = r'''
+  void main(List<String> args) async {
+    try {
+      throw 'error';
+    } catch (e) {
+      print('Caught!');
+    }
+  }
+''';
+
+/// A simple Dart script that throws in user code.
+const simpleThrowingProgram = r'''
+  void main(List<String> args) async {
+    throw 'error';
+  }
+''';

pkg/dds/test/dap/integration/test_support.dart

@@ -31,9 +31,21 @@ final vmServiceAuthCodePathPattern = RegExp(r'^/[\w_\-=]{5,15}/ws$');
 final vmServiceUriPattern = RegExp(r'Connecting to VM Service at ([^\s]+)\s');
 
 /// Expects [actual] to equal the lines [expected], ignoring differences in line
-/// endings.
+/// endings and trailing whitespace.
 void expectLines(String actual, List<String> expected) {
-  expect(actual.replaceAll('\r\n', '\n'), equals(expected.join('\n')));
+  expect(
+    actual.replaceAll('\r\n', '\n').trim(),
+    equals(expected.join('\n').trim()),
+  );
+}
+
+/// Expects [actual] starts with [expected], ignoring differences in line
+/// endings and trailing whitespace.
+void expectLinesStartWith(String actual, List<String> expected) {
+  expect(
+    actual.replaceAll('\r\n', '\n').trim(),
+    startsWith(expected.join('\n').trim()),
+  );
 }
 
 /// Returns the 1-base line in [file] that contains [searchText].