AI 143872: am: CL 143870 am: CL 143869 Change InstrumentationTestRunner so all tests in the application are run when no other arguments are supplied, instead of running only tests in the app's package.
  Original author: brettchabot
  Merged from: //branches/cupcake/...
  Original author: android-build
  Merged from: //branches/donutburger/...

Automated import of CL 143872
diff --git a/test-runner/android/test/ClassPathPackageInfoSource.java b/test-runner/android/test/ClassPathPackageInfoSource.java
index 12bc7f3..877075f 100644
--- a/test-runner/android/test/ClassPathPackageInfoSource.java
+++ b/test-runner/android/test/ClassPathPackageInfoSource.java
@@ -226,8 +226,11 @@
                 String className = apkClassNames.nextElement();
 
                 if (className.startsWith(packageName)) {
+                    String subPackageName = packageName;
                     int lastPackageSeparator = className.lastIndexOf('.');
-                    String subPackageName = className.substring(0, lastPackageSeparator);
+                    if (lastPackageSeparator > 0) {
+                        subPackageName = className.substring(0, lastPackageSeparator);
+                    }
                     if (subPackageName.length() > packageName.length()) {
                         subpackageNames.add(subPackageName);
                     } else if (isToplevelClass(className)) {