Adds tests and documentation for print line ending behavior

Bug:https://github.com/dart-lang/sdk/issues/53161
Change-Id: I3f13af3cb852b3656341922b9656ec91fc413eed
Tested: documentation + unit test only
CoreLibraryReviewExempt: Only adds documentation and adds a unit test to verify existing behavior
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/323426
Reviewed-by: Lasse Nielsen <lrn@google.com>
Commit-Queue: Brian Quinlan <bquinlan@google.com>
Reviewed-by: Sigmund Cherem <sigmund@google.com>

pkg/front_end/testcases/general/sdk_diagnostic.dart.strong.expect

@@ -19,7 +19,7 @@ library;
 // pkg/front_end/testcases/general/sdk_diagnostic.dart:12:8: Error: Too few positional arguments: 1 required, 0 given.
 //   print(incorrectArgument: "fisk");
 //        ^
-// sdk/lib/core/print.dart:8:6: Context: Found this candidate, but the arguments don't match.
+// sdk/lib/core/print.dart:19:6: Context: Found this candidate, but the arguments don't match.
 // void print(Object? object) {
 //      ^^^^^
 //

pkg/front_end/testcases/general/sdk_diagnostic.dart.strong.transformed.expect

@@ -19,7 +19,7 @@ library;
 // pkg/front_end/testcases/general/sdk_diagnostic.dart:12:8: Error: Too few positional arguments: 1 required, 0 given.
 //   print(incorrectArgument: "fisk");
 //        ^
-// sdk/lib/core/print.dart:8:6: Context: Found this candidate, but the arguments don't match.
+// sdk/lib/core/print.dart:19:6: Context: Found this candidate, but the arguments don't match.
 // void print(Object? object) {
 //      ^^^^^
 //

pkg/front_end/testcases/general/sdk_diagnostic.dart.weak.expect

@@ -19,7 +19,7 @@ library;
 // pkg/front_end/testcases/general/sdk_diagnostic.dart:12:8: Error: Too few positional arguments: 1 required, 0 given.
 //   print(incorrectArgument: "fisk");
 //        ^
-// sdk/lib/core/print.dart:8:6: Context: Found this candidate, but the arguments don't match.
+// sdk/lib/core/print.dart:19:6: Context: Found this candidate, but the arguments don't match.
 // void print(Object? object) {
 //      ^^^^^
 //

pkg/front_end/testcases/general/sdk_diagnostic.dart.weak.modular.expect

@@ -19,7 +19,7 @@ library;
 // pkg/front_end/testcases/general/sdk_diagnostic.dart:12:8: Error: Too few positional arguments: 1 required, 0 given.
 //   print(incorrectArgument: "fisk");
 //        ^
-// sdk/lib/core/print.dart:8:6: Context: Found this candidate, but the arguments don't match.
+// sdk/lib/core/print.dart:19:6: Context: Found this candidate, but the arguments don't match.
 // void print(Object? object) {
 //      ^^^^^
 //

pkg/front_end/testcases/general/sdk_diagnostic.dart.weak.transformed.expect

@@ -19,7 +19,7 @@ library;
 // pkg/front_end/testcases/general/sdk_diagnostic.dart:12:8: Error: Too few positional arguments: 1 required, 0 given.
 //   print(incorrectArgument: "fisk");
 //        ^
-// sdk/lib/core/print.dart:8:6: Context: Found this candidate, but the arguments don't match.
+// sdk/lib/core/print.dart:19:6: Context: Found this candidate, but the arguments don't match.
 // void print(Object? object) {
 //      ^^^^^
 //

pkg/vm_service/test/break_on_dart_colon_test.dart

@@ -11,7 +11,7 @@ import 'common/service_test_common.dart';
 import 'common/test_helper.dart';
 
 // Line in core/print.dart
-const int LINE_A = 10;
+const int LINE_A = 19;
 
 testMain() {
   debugger();

runtime/observatory/tests/service/break_on_dart_colon_test.dart

@@ -11,7 +11,7 @@ import 'service_test_common.dart';
 import 'test_helper.dart';
 
 // Line in core/print.dart
-const int LINE_A = 10;
+const int LINE_A = 19;
 
 testMain() {
   debugger();

sdk/lib/core/print.dart

@@ -4,7 +4,18 @@
 
 part of dart.core;
 
-/// Prints a string representation of the object to the console.
+/// Prints an object to the console.
+///
+/// On the web, `object` is converted to a string and that string is output to
+/// the web console using `console.log`.
+///
+/// On native (non-Web) platforms, `object` is converted to a string and that
+/// string is terminated by a line feed (`'\n'`, U+000A) and written to
+/// `stdout`. On Windows, the terminating line feed, and any line feeds in the
+/// string representation of `object`, are output using the Windows line
+/// terminator sequence of (`'\r\n'`, U+000D + U+000A).
+///
+/// Calls to `print` can be intercepted by [Zone.print].
 void print(Object? object) {
   String line = "$object";
   var toZone = printToZone;

tests/standalone/io/print_test.dart

@@ -0,0 +1,74 @@
+// Copyright (c) 2023, 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.
+
+// OtherResources=print_test_script.dart
+
+/// Tests the `dart:core` `print` function.
+///
+/// The actual print code is in "print_test_script.dart" and the output is
+/// validated in this test.
+
+import 'dart:io';
+
+import "package:expect/expect.dart";
+
+final nl = Platform.isWindows ? [13, 10] : [10];
+
+/// Execute "print_test_script.dart" with `command` as an argument and return
+/// the commands stdout as a list of bytes.
+List<int> runTest(String command) {
+  final result = Process.runSync(
+      Platform.executable,
+      []
+        ..addAll(Platform.executableArguments)
+        ..add('--verbosity=warning')
+        ..add(Platform.script.resolve('print_test_script.dart').toFilePath())
+        ..add(command),
+      stdoutEncoding: null);
+
+  if (result.exitCode != 0) {
+    throw AssertionError(
+        'unexpected exit code for command $command: ${result.stderr}');
+  }
+  return result.stdout;
+}
+
+void testSimpleString() {
+  // "Hello World!"
+  final expected = [72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100, ...nl];
+  Expect.listEquals(expected, runTest("simple-string"));
+}
+
+void testStringInternalLineEnding() {
+  // "l1\nl2\nl3"
+  final expected = [108, 49, ...nl, 108, 50, ...nl, 108, 51, ...nl];
+  Expect.listEquals(expected, runTest("string-internal-linefeeds"));
+}
+
+void testStringCarriageReturns() {
+  // "l1\rl2\rl3\r"
+  final expected = [108, 49, 13, 108, 50, 13, 108, 51, 13, ...nl];
+  Expect.listEquals(expected, runTest("string-internal-carriagereturns"));
+}
+
+void testStringCarriageReturnLinefeeds() {
+  // ""l1\r\nl2\r\nl3\r\n""
+  // Notice on Windows this will result in `\r\n` => `\r\r\n'
+  final expected = [108, 49, 13, ...nl, 108, 50, 13, ...nl, 108, 51, 13, ...nl];
+  Expect.listEquals(
+      expected, runTest("string-internal-carriagereturn-linefeeds"));
+}
+
+void testObjectInternalLineEnding() {
+  // Object.toString() => "l1\nl2\nl3"
+  final expected = [108, 49, ...nl, 108, 50, ...nl, 108, 51, ...nl];
+  Expect.listEquals(expected, runTest("object-internal-linefeeds"));
+}
+
+void main() {
+  testSimpleString();
+  testStringInternalLineEnding();
+  testStringCarriageReturns();
+  testObjectInternalLineEnding();
+}

tests/standalone/io/print_test_script.dart

@@ -0,0 +1,39 @@
+// Copyright (c) 2023, 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.
+
+/// This is a companion script to print_test.dart.
+
+import 'dart:io';
+
+class ToString {
+  String _toString;
+
+  ToString(this._toString);
+
+  String toString() => _toString;
+}
+
+main(List<String> arguments) {
+  switch (arguments.last) {
+    case "simple-string":
+      print("Hello World");
+      break;
+    case "string-internal-linefeeds":
+      print("l1\nl2\nl3");
+      break;
+    case "string-internal-carriagereturns":
+      print("l1\rl2\rl3\r");
+      break;
+    case "string-internal-carriagereturn-linefeeds":
+      print("l1\r\nl2\r\nl3\r\n");
+      break;
+    case "object-internal-linefeeds":
+      print(ToString("l1\nl2\nl3"));
+      break;
+    default:
+      stderr.writeln("Command was not recognized");
+      exit(1);
+      break;
+  }
+}

tests/standalone/standalone.status

@@ -62,6 +62,7 @@ verbose_gc_to_bmu_test: SkipByDesign # No verbose_gc in product mode
 http_launch_test: Skip
 io/addlatexhash_test: Skip
 io/issue_46436_test: SkipByDesign # Uses mirrors.
+io/print_test: SkipByDesign # Attempts to spawn dart using Platform.executable
 io/socket_sigpipe_test: SkipByDesign # Spawns server process using Platform.executable
 io/wait_for_event_isolate_test: SkipByDesign # Uses mirrors.
 io/wait_for_event_microtask_test: SkipByDesign # Uses mirrors.