Added functionality to dump relevant status file entries to a single file to make it easier to see …

tools/migration/bin/migrate_batch.dart

Index: tools/migration/bin/migrate_batch.dart
diff --git a/tools/migration/bin/migrate_batch.dart b/tools/migration/bin/migrate_batch.dart
index b0ae2b1f2722a5cf9940da0314a11dc39df77ed4..ca5ad7800fe2462ec60377c25c8b2bb478a3ddeb 100644
--- a/tools/migration/bin/migrate_batch.dart
+++ b/tools/migration/bin/migrate_batch.dart
@@ -13,6 +13,7 @@ import 'dart:io';
 import 'package:path/path.dart' as p;
 
 import 'package:migration/src/log.dart';
+import 'package:status_file/status_file.dart';
 
 const simpleDirs = const ["corelib", "language", "lib"];
 
@@ -62,15 +63,21 @@ void main(List<String> arguments) {
     }
   }
 
+  if ((endIndex - startIndex) == 0) {
+    print(bold("No tests to migrate."));
+    return;
+  }
+
   print("Migrating ${bold(endIndex - startIndex)} tests from ${bold(first)} "
       "to ${bold(last)}...");
   print("");
 
+  tests = tests.getRange(startIndex, endIndex);
   var todos = <String>[];
   var migratedTests = 0;
   var unmigratedTests = 0;
-  for (var i = startIndex; i < endIndex; i++) {
-    if (tests[i].migrate(todos)) {
+  for (var test in tests) {
+    if (test.migrate(todos)) {
       migratedTests++;
     } else {
       unmigratedTests++;
@@ -93,6 +100,50 @@ void main(List<String> arguments) {
 
   print(summary);
   todos.forEach(todo);
+
+  // Print status file entries.
+  var statusFileEntries = new StringBuffer();
+  var statusFiles = loadStatusFiles();
+  for (var statusFile in statusFiles) {
+    statusFileEntries.write(printStatusFileEntries(tests, statusFile));
+  }
+
+  new File("statuses.migration")
+      .writeAsStringSync(statusFileEntries.toString());
+  print(
+      bold("Wrote relevant test status file entries to 'statuses.migration'"));
+}
+
+/// Returns a [String] of the relevant status file entries associated with the
+/// tests in [tests] found in [statusFile].
+String printStatusFileEntries(List<Fork> tests, StatusFile statusFile) {
+  var statusFileEntries = new StringBuffer();

[Bob Nystrom, 2017/07/25 23:48:21]

Instead of creating a new StringBuffer in each call to this whose results are
added to the outer StringBuffer in main(), it will be faster to just pass that
one StringBuffer in and keep adding to it. (Not that this code is super perf
critical, but it's a good habit to be in and doesn't make the code notably more
complex.)

[bkonyi, 2017/07/26 00:27:12]

Done.

+  var filteredStatusFile = new StatusFile(statusFile.path);
+  var testNames = <String>[];
+  for (var test in tests) {
+    testNames.add(test.twoPath.split("/").last.split(".")[0]);
+  }
+  for (var section in statusFile.sections) {
+    StatusSection currentSection = null;

[Bob Nystrom, 2017/07/25 23:48:21]

"= null" isn't needed.

https://www.dartlang.org/guides/language/effective-dart/usage#dont-explicitly...

[bkonyi, 2017/07/26 00:27:12]

Done.

+    for (var entry in section.entries) {
+      for (var testName in testNames) {
+        if (entry.path.contains(testName)) {
+          if (currentSection == null) {
+            currentSection = new StatusSection(section.condition);
+          }
+          currentSection.entries.add(entry);
+        }
+      }
+    }
+    if (currentSection != null) {
+      filteredStatusFile.sections.add(currentSection);
+    }
+  }
+  if (!filteredStatusFile.isEmpty) {
+    statusFileEntries.writeln("Entries for status file ${statusFile.path}:");
+    statusFileEntries.writeln(filteredStatusFile.toString());

[Bob Nystrom, 2017/07/25 23:48:21]

".toString()" isn't needed. StringBuffer.writeln() accepts any object and
automatically calls toString() on it for you.

[bkonyi, 2017/07/26 00:27:12]

Done.

+  }
+  return statusFileEntries.toString();
 }
 
 String toTwoPath(String path) {
@@ -137,7 +188,6 @@ List<Fork> scanTests() {
 
       var fromPath = p.relative(entry.path, from: testRoot);
       var twoPath = p.join(twoDir, p.relative(fromPath, from: fromDir));
-
       var fork = tests.putIfAbsent(twoPath, () => new Fork(twoPath));
       if (fromDir.contains("_strong")) {
         fork.strongPath = fromPath;
@@ -161,6 +211,34 @@ List<Fork> scanTests() {
   return sorted;
 }
 
+List<StatusFile> loadStatusFiles() {
+  var statusFiles = <String, List<StatusFile>>{};

[Bob Nystrom, 2017/07/25 23:48:21]

Looks like my suggestion was wrong and you don't actually need to group the
status files by anything. Maybe discard this and just build one big
List<StatusFile>?

[bkonyi, 2017/07/26 00:27:12]

Done.

+
+  addStatusFile(String fromDir) {
+    var statusFileList = statusFiles.putIfAbsent(fromDir, () => <StatusFile>[]);
+    for (var entry
+        in new Directory(p.join(testRoot, fromDir)).listSync(recursive: true)) {
+      if (!entry.path.endsWith(".status")) continue;
+
+      statusFileList.add(new StatusFile.read(entry.path));
+    }
+  }
+
+  addStatusFile("corelib");
+  addStatusFile("corelib_strong");
+  addStatusFile("html");
+  addStatusFile("isolate");
+  addStatusFile("language");
+  addStatusFile("language_strong");
+  addStatusFile("lib");
+  addStatusFile("lib_strong");
+  var statusFilesList = <StatusFile>[];
+  for (var list in statusFiles.values) {
+    statusFilesList.addAll(list);
+  }
+  return statusFilesList;
+}
+
 /// Moves the file from [from] to [to], which are both assumed to be relative
 /// paths inside "tests".
 void moveFile(String from, String to) {