[tests] Fix formatting when writing diffs

* Normalize white space around source code strings before producing
  diffs by trimming and appending a single newline character.
* Write an empty line between the source code and diff text in
  generation files.
* Run dart format on all test files.

With these changes you should be able to run the hot reload suite with
`--diff write` and dart format the code multiple times without
introducing changes in the file.

Change-Id: Ifc0b1dd7032bd448f5f6568c5aa3c18dde076c71
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/405247
Reviewed-by: Mark Zhou <markzipan@google.com>
Commit-Queue: Nicholas Shahan <nshahan@google.com>

pkg/dev_compiler/test/hot_reload_suite.dart

@@ -575,8 +575,10 @@ abstract class HotReloadSuiteRunner {
             }
             final previousTempUri = generatedCodeDir.uri.resolve('__previous');
             final currentTempUri = generatedCodeDir.uri.resolve('__current');
-            File.fromUri(previousTempUri).writeAsStringSync(previousCode);
-            File.fromUri(currentTempUri).writeAsStringSync(currentCode);
+            // Avoid 'No newline at end of file' messages in the output by
+            // appending a newline to the trimmed source code strings.
+            File.fromUri(previousTempUri).writeAsStringSync('$previousCode\n');
+            File.fromUri(currentTempUri).writeAsStringSync('$currentCode\n');
             final diffOutput = _diffWithFileUris(
                 previousTempUri, currentTempUri,
                 label: test.name);
@@ -623,16 +625,18 @@ abstract class HotReloadSuiteRunner {
             (currentCode, currentDiff) = _splitTestByDiff(currentEdit.fileUri);
             final previousTempUri = generatedCodeDir.uri.resolve('__previous');
             final currentTempUri = generatedCodeDir.uri.resolve('__current');
-            File.fromUri(previousTempUri).writeAsStringSync(previousCode);
-            File.fromUri(currentTempUri).writeAsStringSync(currentCode);
+            // Avoid 'No newline at end of file' messages in the output by
+            // appending a newline to the trimmed source code strings.
+            File.fromUri(previousTempUri).writeAsStringSync('$previousCode\n');
+            File.fromUri(currentTempUri).writeAsStringSync('$currentCode\n');
             final diffOutput = _diffWithFileUris(
                 previousTempUri, currentTempUri,
                 label: test.name);
             File.fromUri(previousTempUri).deleteSync();
             File.fromUri(currentTempUri).deleteSync();
-            final newCurrentText = '$currentCode'
-                '${currentCode.endsWith('\n') ? '' : '\n'}'
-                '$diffOutput\n';
+            // Write an empty line between the code and the diff comment to
+            // agree with the dart formatter.
+            final newCurrentText = '$currentCode\n\n$diffOutput\n';
             File.fromUri(currentEdit.fileUri).writeAsStringSync(newCurrentText);
             _print('Writing updated diff to $currentEdit.fileUri',
                 label: test.name);
@@ -943,16 +947,15 @@ abstract class HotReloadSuiteRunner {
     return (diff1Lines.join('\n'), diff2Lines.join('\n'));
   }
 
-  /// Returns the code and diff portions of [file].
+  /// Returns the code and diff portions of [file] with all leading and trailing
+  /// whitespace trimmed.
   (String, String) _splitTestByDiff(Uri file) {
     final text = File.fromUri(file).readAsStringSync();
     final diffIndex = text.indexOf(testDiffSeparator);
     final diffSplitIndex = diffIndex == -1 ? text.length - 1 : diffIndex;
-    final codeText = text.substring(0, diffSplitIndex);
-    final diffText = text.substring(diffSplitIndex, text.length - 1);
-    // 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);
+    final codeText = text.substring(0, diffSplitIndex).trim();
+    final diffText = text.substring(diffSplitIndex, text.length - 1).trim();
+    return (codeText, diffText);
   }
 }
 

tests/hot_reload/add_library_imports/main.1.dart

@@ -18,6 +18,7 @@ Future<void> main() async {
   await hotReload();
   validate();
 }
+
 /** DIFF **/
 /*
 @@ -2,12 +2,15 @@

tests/hot_reload/add_new_static_field/main.1.dart

@@ -25,6 +25,7 @@ Future<void> main() async {
   Expect.equals('42', helper());
   Expect.equals(1, hotReloadGeneration);
 }
+
 /** DIFF **/
 /*
 @@ -8,10 +8,12 @@

tests/hot_reload/bad_class/main.1.reject.dart

@@ -21,6 +21,7 @@ Future<void> main() async {
   foo = Foo(10);
   Expect.equals(10, foo.a);
 }
+
 /** DIFF **/
 /*
 @@ -9,7 +9,7 @@

tests/hot_reload/call_deleted_top_level_function/main.1.dart

@@ -28,6 +28,7 @@ Future<void> main() async {
   Expect.contains('deleted', helper());
   Expect.equals(1, hotReloadGeneration);
 }
+
 /** DIFF **/
 /*
 @@ -8,15 +8,14 @@

tests/hot_reload/call_deleted_top_level_function_arity_change/main.1.dart

@@ -32,6 +32,7 @@ Future<void> main() async {
   Expect.contains('deleted', helper());
   Expect.equals(1, hotReloadGeneration);
 }
+
 /** DIFF **/
 /*
 @@ -8,15 +8,18 @@

tests/hot_reload/class_added/main.1.dart

@@ -22,6 +22,7 @@ Future<void> main() async {
 
   Expect.equals('hello from A', helper());
 }
+
 /** DIFF **/
 /*
 @@ -9,7 +9,11 @@

tests/hot_reload/class_field_added/main.1.dart

@@ -27,6 +27,7 @@ Future<void> main() async {
   Expect.isNotNull(Foo());
   Expect.equals(2, hotReloadGeneration);
 }
+
 /** DIFF **/
 /*
 @@ -10,6 +10,7 @@

tests/hot_reload/class_field_added/main.2.dart

@@ -28,6 +28,7 @@ Future<void> main() async {
   Expect.isNotNull(Foo());
   Expect.equals(2, hotReloadGeneration);
 }
+
 /** DIFF **/
 /*
 @@ -11,6 +11,7 @@

tests/hot_reload/class_field_removed/main.1.dart

@@ -27,6 +27,7 @@ Future<void> main() async {
   Expect.isNotNull(Foo());
   Expect.equals(2, hotReloadGeneration);
 }
+
 /** DIFF **/
 /*
 @@ -11,7 +11,6 @@

tests/hot_reload/class_field_removed/main.2.dart

@@ -26,6 +26,7 @@ Future<void> main() async {
   Expect.isNotNull(Foo());
   Expect.equals(2, hotReloadGeneration);
 }
+
 /** DIFF **/
 /*
 @@ -10,7 +10,6 @@

tests/hot_reload/class_removed/main.0.dart

@@ -11,7 +11,9 @@ import 'package:reload_test/reload_test_utils.dart';
 class A {
   toString() => 'hello from A';
 }
+
 var list = <dynamic>[];
+
 helper() {
   list.add(A());
   return list[0].toString();

tests/hot_reload/class_removed/main.1.dart

@@ -9,6 +9,7 @@ import 'package:reload_test/reload_test_utils.dart';
 // https://github.com/dart-lang/sdk/blob/f34a2ed99fc1b34cedbd974a5801f8d922121126/runtime/vm/isolate_reload_test.cc#L585
 
 var list = <dynamic>[];
+
 helper() {
   return list[0].toString();
 }
@@ -19,16 +20,19 @@ Future<void> main() async {
 
   Expect.equals('hello from A', helper());
 }
+
 /** DIFF **/
 /*
-@@ -8,12 +8,8 @@
+@@ -8,14 +8,9 @@
  // Adapted from:
  // https://github.com/dart-lang/sdk/blob/f34a2ed99fc1b34cedbd974a5801f8d922121126/runtime/vm/isolate_reload_test.cc#L585
  
 -class A {
 -  toString() => 'hello from A';
 -}
+-
  var list = <dynamic>[];
+ 
  helper() {
 -  list.add(A());
    return list[0].toString();

tests/hot_reload/compile_base_class/lib.1.dart

@@ -10,6 +10,7 @@ class State<U, T> {
     u = l[1] is U ? l[1] : null;
   }
 }
+
 /** DIFF **/
 /*
 @@ -2,7 +2,7 @@

tests/hot_reload/compile_generics/main.1.dart

@@ -26,6 +26,7 @@ Future<void> main() async {
   balance = (MyAccountState(Account())).howAreTheThings().balance();
   Expect.equals(24, balance);
 }
+
 /** DIFF **/
 /*
 @@ -11,7 +11,7 @@

tests/hot_reload/const_field_update/main.1.dart

@@ -21,6 +21,7 @@ Future<void> main() async {
   Expect.equals('0:00:02.000000', helper());
   Expect.equals(1, hotReloadGeneration);
 }
+
 /** DIFF **/
 /*
 @@ -8,7 +8,7 @@

tests/hot_reload/const_to_non_const_class/main.1.reject.dart

@@ -23,6 +23,7 @@ Future<void> main() async {
   await hotReload(expectRejection: true);
   helper();
 }
+
 /** DIFF **/
 /*
 @@ -8,12 +8,12 @@

tests/hot_reload/const_to_non_const_class_empty/main.1.reject.dart

@@ -23,6 +23,7 @@ Future<void> main() async {
   await hotReload(expectRejection: true);
   helper();
 }
+
 /** DIFF **/
 /*
 @@ -8,11 +8,12 @@

tests/hot_reload/constant_identical/main.1.dart

@@ -30,6 +30,7 @@ Future<void> main() async {
   Expect.identical(x, const Fruit('Pear'));
   Expect.identical(x, helper());
 }
+
 /** DIFF **/
 /*
 */

tests/hot_reload/constant_nonidentical/main.1.dart

@@ -32,6 +32,7 @@ Future<void> main() async {
   Expect.identical(x, const Fruit('Pear'));
   Expect.notIdentical(x, helper());
 }
+
 /** DIFF **/
 /*
 @@ -11,6 +11,7 @@

tests/hot_reload/constructor_changed/main.1.dart

@@ -28,6 +28,7 @@ Future<void> main() async {
   Expect.equals(20, savedA.field);
   Expect.equals(10, helper().field);
 }
+
 /** DIFF **/
 /*
 @@ -11,7 +11,7 @@

tests/hot_reload/delete_static_field/main.1.dart

@@ -29,6 +29,7 @@ Future<void> main() async {
 
   Expect.throws(closure);
 }
+
 /** DIFF **/
 /*
 @@ -16,15 +16,11 @@

tests/hot_reload/enum_addition/main.1.dart

@@ -46,9 +46,4 @@ Future<void> main() async {
  
  Future<void> main() async {
    Expect.equals(0, Fruit.Apple.index);
-@@ -25,3 +28,4 @@
-   Expect.equals('Fruit.Banana', Fruit.Banana.toString());
-   helper();
- }
-+
 */

tests/hot_reload/enum_delete/main.1.dart

@@ -39,9 +39,4 @@ Future<void> main() async {
    Expect.equals('Fruit.Cantaloupe', x.toString());
    Expect.type<int>(x.hashCode);
    Expect.equals(2, x.index);
-@@ -23,3 +22,4 @@
-   Expect.type<int>(x.hashCode);
-   Expect.equals(-1, x.index);
- }
-+
 */

tests/hot_reload/enum_equality/main.1.dart

@@ -20,9 +20,4 @@ Future<void> main() async {
 
 /** DIFF **/
 /*
-@@ -17,3 +17,4 @@
-   await hotReload();
-   Expect.equals(Fruit.Banana, x);
- }
-+
 */

tests/hot_reload/enum_identical/main.1.dart

@@ -20,9 +20,4 @@ Future<void> main() async {
 
 /** DIFF **/
 /*
-@@ -17,3 +17,4 @@
-   await hotReload();
-   Expect.identical(Fruit.Banana, x);
- }
-+
 */

tests/hot_reload/enum_identity_reload/main.1.dart

@@ -36,9 +36,4 @@ Future<void> main() async {
 
 /** DIFF **/
 /*
-@@ -33,3 +33,4 @@
-   Expect.equals(z, Fruit.values[x[Fruit.Banana]]);
-   Expect.equals(w, Fruit.values[x[Fruit.Cantaloupe]]);
- }
-+
 */

tests/hot_reload/enum_in_main_library_modified/main.1.dart

@@ -39,9 +39,4 @@ Future<void> main() async {
    toString() => 'foo';
  }
  
-@@ -27,3 +28,4 @@
-   // Modification of an imported library propagates to the importing library.
-   Expect.equals('foo', helper());
- }
-+
 */

tests/hot_reload/enum_referent_shape_change_add/main.1.dart

@@ -76,9 +76,4 @@ Future<void> main() async {
  
    const Fruit(this.name, this.initial);
    final String name;
-@@ -37,3 +40,4 @@
-   await hotReload();
-   Expect.equals('Fruit.Apple', retained.toString());
- }
-+
 */

tests/hot_reload/enum_reorder_identical/main.1.dart

@@ -30,9 +30,4 @@ Future<void> main() async {
  
  var x;
  
-@@ -18,3 +18,4 @@
-   Expect.equals(Fruit.Banana, x);
-   Expect.identical(Fruit.Banana, x);
- }
-+
 */

tests/hot_reload/enum_retained_hash/main.1.dart

@@ -132,9 +132,4 @@ Future<void> main() async {
  }
  
  enum C {
-@@ -97,3 +97,4 @@
-   Expect.identical(c3, C.C3, 'i-c3');
-   Expect.equals(c3.hashCode, C.C3.hashCode, 'h-c3');
- }
-+
 */

tests/hot_reload/enum_shape_change/main.1.dart

@@ -28,26 +28,20 @@ Future<void> main() async {
 
 /** DIFF **/
 /*
-@@ -8,8 +8,15 @@
+@@ -8,7 +8,14 @@
  // Adapted from:
  // https://github.com/dart-lang/sdk/blob/be2aabd91c67f7f331c49cb74e18fe5e469f04db/runtime/vm/isolate_reload_test.cc#L2308
  
 -enum Fruit { Apple, Banana }
 +enum Fruit {
 +  Apple('Apple', 'A'),
 +  Banana('Banana', 'B');
- 
++
 +  const Fruit(this.name, this.initial);
 +  final String name;
 +  final String initial;
 +}
-+
+ 
  var retained;
  
- Future<void> main() async {
-@@ -18,3 +25,4 @@
-   await hotReload();
-   Expect.equals('A', retained.initial);
- }
-+
 */

tests/hot_reload/enum_shape_change_add/main.1.dart

@@ -61,9 +61,4 @@ Future<void> main() async {
  
  Future<void> main() async {
    retained = Fruit.Apple;
-@@ -20,3 +32,4 @@
-   await hotReload();
-   helper();
- }
-+
 */

tests/hot_reload/enum_shape_change_remove/main.1.dart

@@ -25,7 +25,7 @@ Future<void> main() async {
 
 /** DIFF **/
 /*
-@@ -8,12 +8,18 @@
+@@ -8,12 +8,17 @@
  // Adapted from:
  // https://github.com/dart-lang/sdk/blob/be2aabd91c67f7f331c49cb74e18fe5e469f04db/runtime/vm/isolate_reload_test.cc#L2371
  
@@ -45,5 +45,4 @@ Future<void> main() async {
    await hotReload();
    Expect.equals('Fruit.Deleted enum value from Fruit', retained.toString());
  }
-+
 */