Fix red tests

Change-Id: I53ae3052149aff857865c8ca64f946990e61402e
diff --git a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryTestBase.java b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryTestBase.java
index 570ccb8..fd59825 100644
--- a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryTestBase.java
+++ b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryTestBase.java
@@ -143,6 +143,10 @@
       }
       return desugaredLib;
     } catch (Exception e) {
+      // Don't wrap assumption violation so junit can catch it.
+      if (e instanceof RuntimeException) {
+        throw ((RuntimeException) e);
+      }
       throw new RuntimeException(e);
     }
   }