8373876: StackWalkNativeToJava print more output in case of failures

Reviewed-by: dholmes, mdoerr

Author: MBaesken

test/hotspot/jtreg/runtime/ErrorHandling/StackWalkNativeToJava.java

@@ -70,7 +70,11 @@ public static void testStackWalkNativeToJavaNative(String... extraFlags) throws
         output.shouldNotContain("java.lang.RuntimeException: Reached statement after obj.wait()");
         output.shouldNotContain("[error occurred during error reporting (printing native stack");
         String[] res = output.getOutput().split("StackWalkNativeToJava\\$TestNativeToJavaNative\\.callNativeMethod\\(\\)V");
-        assertTrue(res.length - 1 == 2, res.length - 1);
+        if (res.length != 3) {
+            output.reportDiagnosticSummary();
+        }
+
+        assertTrue(res.length == 3, res.length);
         output.shouldNotHaveExitValue(0);
     }
 
@@ -104,7 +108,11 @@ public static void testStackWalkNativeToJava(String... extraFlags) throws Except
         output.shouldNotContain("java.lang.RuntimeException: Reached statement after synchronized");
         output.shouldNotContain("[error occurred during error reporting (printing native stack");
         String[] res = output.getOutput().split("StackWalkNativeToJava\\$TestNativeToJava\\.callVMMethod\\(\\)V");
-        assertTrue(res.length - 1 == 2, res.length - 1);
+        if (res.length != 3) {
+            output.reportDiagnosticSummary();
+        }
+
+        assertTrue(res.length == 3, res.length);
         output.shouldNotHaveExitValue(0);
     }
 
@@ -131,4 +139,4 @@ private static void assertTrue(boolean condition, int count) {
             throw new RuntimeException("Count error: count was " + count);
         }
     }
-}
+}