Move the status file parser into its own package.

tools/testing/dart/expectation_set.dart

 // Copyright (c) 2017, 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 'dart:io';
+
+import 'package:status_file/expectation.dart';
+import 'package:status_file/status_file.dart';
+
 import 'configuration.dart';
 import 'environment.dart';
-import 'expectation.dart';
-import 'status_file.dart';
 
 /// Tracks the [Expectation]s associated with a set of file paths.
 ///
 /// For any given file path, returns the expected test results for that file.
 /// A set can be loaded from a collection of status files. A file path may
 /// exist in multiple files (or even multiple sections within the file). When
 /// that happens, all of the expectations of every entry are combined.
 class ExpectationSet {
   /// Reads the expectations defined by the status files at [statusFilePaths]
   /// when in [configuration].
   static ExpectationSet read(
       List<String> statusFilePaths, Configuration configuration) {
-    var environment = new Environment(configuration);
-    var expectations = new ExpectationSet._();
-    for (var path in statusFilePaths) {
-      var file = new StatusFile.read(path);
-      for (var section in file.sections) {
-        if (section.isEnabled(environment)) {
-          for (var entry in section.entries) {
-            expectations.addEntry(entry);
+    try {
+      var environment = new ConfigurationEnvironment(configuration);
+      var expectations = new ExpectationSet._();
+      for (var path in statusFilePaths) {
+        var file = new StatusFile.read(path);
+        file.validate(environment);
+        for (var section in file.sections) {
+          if (section.isEnabled(environment)) {
+            for (var entry in section.entries) {
+              expectations.addEntry(entry);
+            }
           }
         }
       }
+
+      return expectations;
+    } on SyntaxError catch (error) {
+      stderr.writeln(error.toString());
+      exit(1);
+
+      throw "unreachable";
     }
-
-    return expectations;
   }
 
   // Only create one copy of each Set<Expectation>.
   // We just use .toString as a key, so we may make a few
   // sets that only differ in their toString element order.
   static Map<String, Set<Expectation>> _cachedSets = {};
 
   Map<String, Set<Expectation>> _map = {};
   Map<String, List<RegExp>> _keyToRegExps;
 
@@ skipping 67 matching lines @@
         var component = splitKey[i];
         var regExp = regExpCache.putIfAbsent(component,
             () => new RegExp("^${splitKey[i]}\$".replaceAll('*', '.*')));
         regExps[i] = regExp;
       }
 
       _keyToRegExps[key] = regExps;
     });
   }
 }