Replace the existing unittest APIs with the new runner infrastructure.

lib/src/utils.dart

Index: lib/src/utils.dart
diff --git a/lib/src/utils.dart b/lib/src/utils.dart
index da2192764a1af63e56830205f26e5129dc3acd06..6b0939fe5ccf805bcf9ffb33e5e9d86b045eb1c1 100644
--- a/lib/src/utils.dart
+++ b/lib/src/utils.dart
@@ -13,48 +13,38 @@ import 'package:stack_trace/stack_trace.dart';
 /// The return type should only ever by [Future] or void.
 typedef AsyncFunction();
 
+/// A regular expression to match the exception prefix that some exceptions'
+/// [Object.toString] values contain.
+final _exceptionPrefix = new RegExp(r'^([A-Z][a-zA-Z]*)?(Exception|Error): ');
+
+/// Get a string description of an exception.
+///
+/// Many exceptions include the exception class name at the beginning of their
+/// [toString], so we remove that if it exists.
+String getErrorMessage(error) =>
+  error.toString().replaceFirst(_exceptionPrefix, '');
+
 /// Indent each line in [str] by two spaces.
 String indent(String str) =>
     str.replaceAll(new RegExp("^", multiLine: true), "  ");
 
-/// A pair of values.
-class Pair<E, F> {
-  final E first;
-  final F last;
-
-  Pair(this.first, this.last);
-
-  String toString() => '($first, $last)';
-
-  bool operator ==(other) {
-    if (other is! Pair) return false;
-    return other.first == first && other.last == last;
-  }
-
-  int get hashCode => first.hashCode ^ last.hashCode;
-}
-
-/// Returns a Trace object from a StackTrace object or a String, or the
-/// unchanged input if formatStacks is false;
-Trace getTrace(stack, bool formatStacks, bool filterStacks) {
-  Trace trace;
-  if (stack == null || !formatStacks) return null;
-  if (stack is String) {
-    trace = new Trace.parse(stack);
-  } else if (stack is StackTrace) {
-    trace = new Trace.from(stack);
-  } else {
-    throw new Exception('Invalid stack type ${stack.runtimeType} for $stack.');
-  }
+/// A regular expression matching the path to a temporary file used to start an
+/// isolate.
+///
+/// These paths aren't relevant and are removed from stack traces.
+final _isolatePath =
+    new RegExp(r"/unittest_[A-Za-z0-9]{6}/runInIsolate\.dart$");
 
-  if (!filterStacks) return trace;
+/// Returns [stackTrace] converted to a [Chain] with all irrelevant frames
+/// folded together.
+Chain terseChain(StackTrace stackTrace) {
+  return new Chain.forTrace(stackTrace).foldFrames((frame) {
+    if (frame.package == 'unittest') return true;
 
-  // Format the stack trace by removing everything above TestCase._runTest,
-  // which is usually going to be irrelevant. Also fold together unittest and
-  // core library calls so only the function the user called is visible.
-  return new Trace(trace.frames.takeWhile((frame) {
-    return frame.package != 'unittest' || frame.member != 'TestCase._runTest';
-  })).terse.foldFrames((frame) => frame.package == 'unittest' || frame.isCore);
+    // Filter out frames from our isolate bootstrap as well.
+    if (frame.uri.scheme != 'file') return false;
+    return frame.uri.path.contains(_isolatePath);
+  }, terse: true);
 }
 
 /// Flattens nested [Iterable]s inside an [Iterable] into a single [List]