[reload_test] Adding diffs to existing tests.

Change-Id: Icf7135ae46159ca834a54849c72405eec83f9b4f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/364384
Reviewed-by: Nicholas Shahan <nshahan@google.com>
Commit-Queue: Mark Zhou <markzipan@google.com>

pkg/dev_compiler/test/hot_reload_suite.dart

@@ -268,7 +268,14 @@ Future<void> main(List<String> args) async {
       throw Exception('Too many generations specified in test '
           '(requested: $maxGenerations, max: $globalMaxGenerations).');
     }
-    switch (argResults['diff']) {
+
+    var diffMode = argResults['diff']!;
+    if (fe_shared.isWindows && diffMode != 'ignore') {
+      _print("Diffing isn't supported on Windows. Defaulting to 'ignore'.",
+          label: testName);
+      diffMode = 'ignore';
+    }
+    switch (diffMode) {
       case 'check':
         _print('Checking source file diffs.', label: testName);
         filesByGeneration.forEach((basename, filesQueue) {
@@ -701,26 +708,32 @@ void _debugPrint(String message, {String? label}) {
 ///
 /// If [commented] is set, the output will be wrapped in multiline comments
 /// and the diff separator.
+///
+/// If [trimHeaders] is set, the leading '+++' and '---' file headers will be
+/// removed.
 String _diffWithFileUris(Uri file1, Uri file2,
-    {String label = '', bool commented = true}) {
+    {String label = '', bool commented = true, bool trimHeaders = true}) {
   final file1Path = file1.toFilePath();
   final file2Path = file2.toFilePath();
-  _debugPrint(
-      "Running diff with 'diff -dy --suppress-common-lines"
-      " --expand-tabs $file1Path $file2Path'.",
-      label: label);
-  final diffProcess = Process.runSync('diff', [
-    '-dy',
-    '--suppress-common-lines',
+  final diffArgs = [
+    '-du',
+    '--width=120',
     '--expand-tabs',
     file1Path,
     file2Path
-  ]);
+  ];
+  _debugPrint("Running diff with 'diff ${diffArgs.join(' ')}'.", label: label);
+  final diffProcess = Process.runSync('diff', diffArgs);
   final errOutput = diffProcess.stderr as String;
   if (errOutput.isNotEmpty) {
     throw Exception('diff failed with:\n$errOutput');
   }
-  final output = diffProcess.stdout as String;
+  var output = diffProcess.stdout as String;
+  if (trimHeaders) {
+    // Skip the first two lines.
+    // TODO(markzipan): Add support for Windows-style line endings.
+    output = output.split('\n').skip(2).join('\n');
+  }
   return commented ? '$testDiffSeparator\n/*\n$output*/' : output;
 }
 
@@ -731,7 +744,9 @@ String _diffWithFileUris(Uri file1, Uri file2,
   final diffSplitIndex = diffIndex == -1 ? text.length - 1 : diffIndex;
   final codeText = text.substring(0, diffSplitIndex);
   final diffText = text.substring(diffSplitIndex, text.length - 1);
-  return (codeText, diffText);
+  // Avoid 'No newline at end of file' messages in the output by appending a
+  // newline if one is not already trailing.
+  return ('$codeText${codeText.endsWith('\n') ? '' : '\n'}', diffText);
 }
 
 abstract class HotReloadSuiteRunner {

tests/hot_reload/add_library_imports/main.1.dart

@@ -18,3 +18,24 @@ Future<void> main() async {
   await hotReload();
   validate();
 }
+/** DIFF **/
+/*
+@@ -2,12 +2,15 @@
+ import 'package:reload_test/reload_test_utils.dart';
+ 
+ import 'dart:math';
++import 'dart:convert';
+ 
+ void validate() {
+-  // Initial program is valid. Symbols in 'dart:math' are visible.
+-  Expect.equals(0, hotReloadGeneration);
++  // Symbols in 'dart:convert' are visible after hot reload.
++  Expect.equals(1, hotReloadGeneration);
+   Expect.equals(e, 2.718281828459045);
+   Expect.type<double>(e);
++  Expect.type<Codec>(utf8);
++  Expect.type<Function>(jsonEncode);
+ }
+ 
+ Future<void> main() async {
+*/

tests/hot_reload/bad_class/main.1.dart

@@ -19,3 +19,15 @@ Future<void> main() async {
   await hotReload();
   throw Exception('This should never run.');
 }
+/** DIFF **/
+/*
+@@ -9,7 +9,7 @@
+ // https://github.com/dart-lang/sdk/blob/36c0788137d55c6c77f4b9a8be12e557bc764b1c/runtime/vm/isolate_reload_test.cc#L364
+ 
+ class Foo {
+-  final a;
++  final a kjsdf ksjdf;
+   Foo(this.a);
+ }
+ 
+*/

tests/hot_reload/compile_base_class/lib.1.dart

@@ -10,3 +10,15 @@ class State<U, T> {
     u = l[1] is U ? l[1] : null;
   }
 }
+/** DIFF **/
+/*
+@@ -2,7 +2,7 @@
+ // 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.
+ 
+-class State<T, U> {
++class State<U, T> {
+   T? t;
+   U? u;
+   State(List l) {
+*/

tests/hot_reload/compile_generics/main.1.dart

@@ -26,3 +26,15 @@ Future<void> main() async {
   balance = (MyAccountState(Account())).howAreTheThings().balance();
   Expect.equals(24, balance);
 }
+/** DIFF **/
+/*
+@@ -11,7 +11,7 @@
+ // https://github.com/dart-lang/sdk/blob/36c0788137d55c6c77f4b9a8be12e557bc764b1c/runtime/vm/isolate_reload_test.cc#L204
+ 
+ class Account {
+-  int balance() => 42;
++  int balance() => 24;
+ }
+ 
+ class MyAccountState extends State<Account> {
+*/

tests/hot_reload/framework_timing_test/main.1.dart

@@ -31,3 +31,40 @@ void main() {
 
   hotRestart();
 }
+/** DIFF **/
+/*
+@@ -7,25 +7,25 @@
+ import 'package:expect/expect.dart';
+ import 'package:reload_test/reload_test_utils.dart';
+ 
+-var x = 'Hello World';
++var x = 'Hello Foo';
+ 
+ void main() {
+-  Expect.equals('Hello World', x);
+-  Expect.equals(0, hotRestartGeneration);
++  Expect.equals('Hello Foo', x);
++  Expect.equals(1, hotRestartGeneration);
+ 
+   scheduleMicrotask(() {
+-    Expect.equals(0, hotRestartGeneration);
++    Expect.equals(1, hotRestartGeneration);
+   });
+   Future<Null>.microtask(() {
+     throw x;
+   }).catchError((e, stackTrace) {
+-    Expect.equals("Hello World", e);
+-    Expect.equals(0, hotRestartGeneration);
++    Expect.equals("Hello Foo", e);
++    Expect.equals(1, hotRestartGeneration);
+   }).then((_) {
+-    Expect.equals(0, hotRestartGeneration);
++    Expect.equals(1, hotRestartGeneration);
+   });
+   Future.delayed(Duration(seconds: 5), () {
+-    throw Exception('Future from main.0.dart before hot restart. '
++    throw Exception('Future from main.1.dart before hot restart. '
+         'This should never run.');
+   });
+ 
+*/

tests/hot_reload/framework_timing_test/main.2.dart

@@ -31,3 +31,40 @@ void main() {
 
   hotRestart();
 }
+/** DIFF **/
+/*
+@@ -7,25 +7,25 @@
+ import 'package:expect/expect.dart';
+ import 'package:reload_test/reload_test_utils.dart';
+ 
+-var x = 'Hello Foo';
++var x = 'Hello Bar';
+ 
+ void main() {
+-  Expect.equals('Hello Foo', x);
+-  Expect.equals(1, hotRestartGeneration);
++  Expect.equals('Hello Bar', x);
++  Expect.equals(2, hotRestartGeneration);
+ 
+   scheduleMicrotask(() {
+-    Expect.equals(1, hotRestartGeneration);
++    Expect.equals(2, hotRestartGeneration);
+   });
+   Future<Null>.microtask(() {
+     throw x;
+   }).catchError((e, stackTrace) {
+-    Expect.equals("Hello Foo", e);
+-    Expect.equals(1, hotRestartGeneration);
++    Expect.equals("Hello Bar", e);
++    Expect.equals(2, hotRestartGeneration);
+   }).then((_) {
+-    Expect.equals(1, hotRestartGeneration);
++    Expect.equals(2, hotRestartGeneration);
+   });
+   Future.delayed(Duration(seconds: 5), () {
+-    throw Exception('Future from main.1.dart before hot restart. '
++    throw Exception('Future from main.2.dart before hot restart. '
+         'This should never run.');
+   });
+ 
+*/

tests/hot_reload/general_test/b.1.dart

@@ -1 +1,7 @@
 get line => "part3";
+/** DIFF **/
+/*
+@@ -1 +1 @@
+-get line => "part1";
++get line => "part3";
+*/

tests/hot_reload/general_test/b.3.dart

@@ -1 +1,7 @@
 get line => "part5";
+/** DIFF **/
+/*
+@@ -1 +1 @@
+-get line => "part3";
++get line => "part5";
+*/

tests/hot_reload/general_test/b.4.dart

@@ -1 +1,7 @@
 get line => "part4";
+/** DIFF **/
+/*
+@@ -1 +1 @@
+-get line => "part5";
++get line => "part4";
+*/

tests/hot_reload/general_test/c.4.dart

@@ -8,3 +8,18 @@ class B {
 }
 
 var bField = B(a: (String s) => "$s");
+/** DIFF **/
+/*
+@@ -1 +1,10 @@
+-String g() => "";
++String g() {
++  return bField.a("a");
++}
++
++class B {
++  dynamic a;
++  B({this.a});
++}
++
++var bField = B(a: (String s) => "$s");
+*/

tests/hot_reload/general_test/c.5.dart

@@ -9,3 +9,18 @@ class B {
 }
 
 var bField = B(a: (String s) => "$s");
+/** DIFF **/
+/*
+@@ -1,9 +1,10 @@
+ String g() {
+-  return bField.a("a");
++  return bField.a("a") + (bField.b ?? "c");
+ }
+ 
+ class B {
+   dynamic a;
++  dynamic b;
+   B({this.a});
+ }
+ 
+*/

tests/hot_reload/general_test/main.1.dart

@@ -53,3 +53,6 @@ Future<void> main() async {
   Expect.equals('ac', topLevel);
   Expect.equals(5, hotReloadGeneration);
 }
+/** DIFF **/
+/*
+*/

tests/hot_reload/general_test/main.2.dart

@@ -53,3 +53,15 @@ Future<void> main() async {
   Expect.equals('ac', topLevel);
   Expect.equals(5, hotReloadGeneration);
 }
+/** DIFF **/
+/*
+@@ -11,7 +11,7 @@
+ import 'b.dart';
+ import 'c.dart';
+ 
+-f() => "$line part2";
++f() => "$line part4";
+ 
+ Future<void> main() async {
+   // Initial program is valid.
+*/

tests/hot_reload/general_test/main.3.dart

@@ -53,3 +53,15 @@ Future<void> main() async {
   Expect.equals('ac', topLevel);
   Expect.equals(5, hotReloadGeneration);
 }
+/** DIFF **/
+/*
+@@ -11,7 +11,7 @@
+ import 'b.dart';
+ import 'c.dart';
+ 
+-f() => "$line part4";
++f() => "$line part6";
+ 
+ Future<void> main() async {
+   // Initial program is valid.
+*/

tests/hot_reload/general_test/main.4.dart

@@ -53,3 +53,6 @@ Future<void> main() async {
   Expect.equals('ac', topLevel);
   Expect.equals(5, hotReloadGeneration);
 }
+/** DIFF **/
+/*
+*/

tests/hot_reload/general_test/main.5.dart

@@ -53,3 +53,6 @@ Future<void> main() async {
   Expect.equals('ac', topLevel);
   Expect.equals(5, hotReloadGeneration);
 }
+/** DIFF **/
+/*
+*/

tests/hot_reload/hot_restart_constant_equality/library_b.1.dart

@@ -6,3 +6,13 @@ import 'library_a.dart';
 
 int variableToModifyToForceRecompile = 45;
 B get value2 => const B(2);
+/** DIFF **/
+/*
+@@ -4,5 +4,5 @@
+ 
+ import 'library_a.dart';
+ 
+-int variableToModifyToForceRecompile = 23;
++int variableToModifyToForceRecompile = 45;
+ B get value2 => const B(2);
+*/

tests/hot_reload/hot_restart_constant_equality/main.1.dart

@@ -31,3 +31,15 @@ void main() {
   Expect.equals('ConstObject(reloadVariable: 45, ConstantEqualitySuccess)',
       '${const ConstObject().text}');
 }
+/** DIFF **/
+/*
+@@ -28,7 +28,6 @@
+ }
+ 
+ void main() {
+-  Expect.equals('ConstObject(reloadVariable: 23, ConstantEqualitySuccess)',
++  Expect.equals('ConstObject(reloadVariable: 45, ConstantEqualitySuccess)',
+       '${const ConstObject().text}');
+-  hotRestart();
+ }
+*/

tests/hot_reload/lazy_static_initializers/main.1.dart

@@ -25,3 +25,15 @@ Future<void> main() async {
   Expect.equals(3, hotReloadGeneration);
   Expect.equals("before", value);
 }
+/** DIFF **/
+/*
+@@ -5,7 +5,7 @@
+ import 'package:expect/expect.dart';
+ import 'package:reload_test/reload_test_utils.dart';
+ 
+-var value = "unused";
++var value = "before";
+ 
+ Future<void> main() async {
+   // Declare an unreferenced lazy static field.
+*/