Split serialization tests further

tests/compiler/dart2js/serialization/test_helper.dart

Index: tests/compiler/dart2js/serialization/test_helper.dart
diff --git a/tests/compiler/dart2js/serialization/test_helper.dart b/tests/compiler/dart2js/serialization/test_helper.dart
index 9d3115f51e35ca794c3b51d5132d6968d835b442..b4c99f4b95b3ae0f3551cda3d5c4257fad5c35bc 100644
--- a/tests/compiler/dart2js/serialization/test_helper.dart
+++ b/tests/compiler/dart2js/serialization/test_helper.dart
@@ -13,6 +13,7 @@ import 'package:compiler/src/elements/elements.dart';
 import 'package:compiler/src/serialization/equivalence.dart';
 import 'package:compiler/src/tree/nodes.dart';
 import 'package:expect/expect.dart';
+import 'test_data.dart';
 
 Check currentCheck;
 
@@ -589,3 +590,23 @@ void checkResolvedAsts(Compiler compiler1, Element member1,
   testResolvedAstEquivalence(
       resolvedAst1, resolvedAst2, const CheckStrategy());
 }
+
+/// Return the test arguments for testing the [index]th segment (1-based) of

[Bill Hesse, 2016/07/20 13:46:45]

I think you should have two functions, one for returning a single test, and
another for returning a computed range.  That is better than overloading
negative numbers.

Could you also check the values against skip and count, to make sure they are
valid?

[Johnni Winther, 2016/07/25 08:30:08]

Done.

+/// the [TESTS] split into [count] groups. The first [skip] tests are excluded
+/// from the automatic grouping and tested if `index <= 0`.
+List<String> testSegment(int index, int count, int skip) {
+
+  int segmentNumber(int i) {
+    return skip + i * (TESTS.length - skip) ~/ count;
+  }
+
+  if (index <= 0) {
+    return ['${-index}', '${-index}'];
+  } else if (index == 1 && skip != 0) {
+    return ['${skip}', '${segmentNumber(index) - 1}'];
+  } else if (index  == count) {
+    return ['${segmentNumber(index - 1)}'];
+  } else {
+    return ['${segmentNumber(index - 1)}', '${segmentNumber(index) - 1}'];
+  }
+}