Refactor and clean up the status file parsing code.

tools/testing/dart/expectation.dart

Index: tools/testing/dart/expectation.dart
diff --git a/tools/testing/dart/expectation.dart b/tools/testing/dart/expectation.dart
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+++ b/tools/testing/dart/expectation.dart
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+// 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.
+
+/// The possible outcomes from running a test.
+class Expectation {
+  /// The test completed normally and did what it intended to do.
+  static final Expectation pass = new Expectation._('Pass');
+
+  /// The process aborted in a way that is not a potential runtime error coming
+  /// from the test itself. This is not considered a failure. It means an
+  /// error happened so fundamental that success/failure could not be
+  /// determined. Includes:
+  ///
+  /// * The Dart VM itself crashes, but not from an unhandled exception in user
+  ///   code.
+  ///
+  /// * When running dart2js on top of the VM to compile some code, the VM
+  ///   exits with a non-zero exit code or uncaught exception -- meaning an
+  ///   internal exception in dart2js itself.
+  ///
+  /// * The browser process crashes.
+  static final Expectation crash = new Expectation._('Crash');
+
+  /// The test did not complete (either successfully or unsuccessfully) in the
+  /// amount of time that the test runner gave it.
+  static final Expectation timeout = new Expectation._('Timeout');
+
+  /// The test completed but did not produce the intended output.
+  ///
+  /// This status is rarely used directly. Instead, most of the expectations
+  /// below refine this into more specific reasons *why* it failed.
+  static final Expectation fail = new Expectation._('Fail');
+
+  /// The test compiled and began executing but then threw an uncaught
+  /// exception or produced the wrong output.
+  static final Expectation runtimeError =
+      new Expectation._('RuntimeError', group: fail);
+
+  /// The test failed with an error at compile time and did not execute any
+  /// code.
+  ///
+  /// * For a VM test, means the VM exited with a "compile error" exit code 254.
+  /// * For an analyzer test, means the analyzer reported a static error.
+  /// * For a dart2js test, means dart2js reported a compile error.
+  static final Expectation compileTimeError =
+      new Expectation._('CompileTimeError', group: fail);
+
+  /// The test itself contains a comment with `@runtime-error` in it,
+  /// indicating it should have produced a runtime error when run. But when it
+  /// was run, the test completed without error.
+  static final Expectation missingRuntimeError =
+      new Expectation._('MissingRuntimeError', group: fail);
+
+  /// The test itself contains a comment with `@compile-error` in it,
+  /// indicating it should have produced an error when compiled. But when it
+  /// was compiled, no error was reported.
+  static final Expectation missingCompileTimeError =
+      new Expectation._('MissingCompileTimeError', group: fail);
+
+  /// When the test is processed by analyzer, a static warning should be
+  /// reported.
+  static final Expectation staticWarning =
+      new Expectation._('StaticWarning', group: fail);
+
+  /// The test itself contains a comment with `@static-warning` in it,
+  /// indicating analyzer should report a static warning when analyzing it, but
+  /// analysis did not produce any warnings.
+  static final Expectation missingStaticWarning =
+      new Expectation._('MissingStaticWarning', group: fail);
+
+  /// An invocation of "pub get" exited with a non-zero exit code.
+  // TODO(rnystrom): Is this still used? If not, remove.
+  static final Expectation pubGetError =
+      new Expectation._('PubGetError', group: fail);
+
+  /// The stdout or stderr produced by the test was not valid UTF-8 and could
+  /// not be decoded.
+  // TODO(rnystrom): The only test that uses this expectation is the one that
+  // tests that the test runner handles this expectation. Remove it?
+  static final Expectation nonUtf8Error =
+      new Expectation._('NonUtf8Output', group: fail);
+
+  /// The VM exited with the special exit code 252.
+  static final Expectation dartkCrash =
+      new Expectation._('DartkCrash', group: crash);
+
+  /// A timeout occurred in a test using the Kernel-based front end.
+  static final Expectation dartkTimeout =
+      new Expectation._('DartkTimeout', group: timeout);
+
+  /// A compile error was reported on a test compiled using the Kernel-based
+  /// front end.
+  static final Expectation dartkCompileTimeError =
+      new Expectation._('DartkCompileTimeError', group: compileTimeError);
+
+  // "meta expectations"
+  /// A marker applied to a test to indicate that the other non-pass
+  /// expectations are intentional and not a result of bugs or features that
+  /// have yet to be implemented.
+  ///
+  /// For example, a test marked "RuntimeError, Ok" means "This test is
+  /// *supposed* to fail at runtime."
+  // TODO(rnystrom): This is redundant with other mechanisms like
+  // `@runtime-error` and the markers in analyzer tests for stating where a
+  // static error should be reported. It leads to perpetually larger status
+  // files and means a reader of a test can't tell what the intended behavior
+  // actually is without knowing which status files mention it. Remove.
+  static final Expectation ok = new Expectation._('Ok', isMeta: true);
+
+  /// A marker that indicates the test takes longer to complete than most tests.
+  /// Tells the test runner to increase the timeout when running it.
+  static final Expectation slow = new Expectation._('Slow', isMeta: true);
+
+  /// Tells the test runner to not attempt to run the test.
+  ///
+  /// This means the test runner does not compare the test's actual results with
+  /// the expected results at all. This expectation should be avoided since it's
+  /// doesn't indicate *why* the test is being skipped and means we won't
+  /// notice if the actual behavior of the test changes.
+  static final Expectation skip = new Expectation._('Skip', isMeta: true);
+
+  /// Tells the test runner to skip the test because it takes too long to
+  /// complete.
+  ///
+  /// Prefer this over timeout since this avoids wasting CPU resources running
+  /// a test we know won't complete.
+  static final Expectation skipSlow =
+      new Expectation._('SkipSlow', isMeta: true, group: skip);
+
+  /// Skips this test because it is not intended to be meaningful for a certain
+  /// reason or on some configuration.
+  ///
+  /// For example, tests that use dart:io are SkipByDesign on the browser since
+  /// dart:io isn't supported there.
+  static final Expectation skipByDesign =
+      new Expectation._('SkipByDesign', isMeta: true);
+
+  /// Can be returned by the test runner to say the result should be ignored,
+  /// and assumed to meet the expectations, due to an infrastructure failure.
+  ///
+  /// This should not appear in status files.
+  static final Expectation ignore = new Expectation._('Ignore');
+
+  /// Used by pkg/front_end/lib/src/fasta/testing, but not used by test.dart.
+  /// Included here so that we can parse .status files that contain it.
+  static final Expectation verificationError =
+      new Expectation._('VerificationError');
+
+  /// Maps case-insensitive names to expectations.
+  static Map<String, Expectation> _all = new Map.fromIterable(<Expectation>[
+    pass,
+    crash,
+    timeout,
+    fail,
+    runtimeError,
+    compileTimeError,
+    missingRuntimeError,
+    missingCompileTimeError,
+    staticWarning,
+    missingStaticWarning,
+    pubGetError,
+    nonUtf8Error,
+    dartkCrash,
+    dartkTimeout,
+    dartkCompileTimeError,
+    ok,
+    slow,
+    skip,
+    skipSlow,
+    skipByDesign,
+    ignore,
+    verificationError,
+  ], key: (Expectation expectation) => expectation._name.toLowerCase());
+
+  /// Looks up the expectation with [name].
+  static Expectation find(String name) {
+    var expectation = _all[name.toLowerCase()];
+    if (expectation == null) {
+      throw new ArgumentError("Could not find an expectation named '$name'.");
+    }
+
+    return expectation;
+  }
+
+  final String _name;
+  final Expectation _group;
+
+  /// Whether this expectation is a test outcome. If not, it's a "meta marker".
+  final bool isOutcome;
+
+  Expectation._(this._name, {Expectation group, bool isMeta: false})
+      : _group = group,
+        isOutcome = !isMeta;
+
+  bool canBeOutcomeOf(Expectation expectation) {
+    var outcome = this;
+    if (outcome == ignore) return true;
+
+    while (outcome != null) {
+      if (outcome == expectation) {
+        return true;
+      }
+      outcome = outcome._group;
+    }
+
+    return false;
+  }
+
+  String toString() => _name;
+}