java_gen: first shot at unit tests
diff --git a/test_data/__init__.py b/test_data/__init__.py
index f21770b..7a55c11 100644
--- a/test_data/__init__.py
+++ b/test_data/__init__.py
@@ -45,6 +45,9 @@
                 result.append(dirname + '/' + filename)
     return sorted(result)
 
+def exists(name):
+    return os.path.exists(os.path.join(_test_data_dir, name))
+
 def read(name):
     """
     Read, parse, and return a test data file
diff --git a/test_data/of10/hello.data b/test_data/of10/hello.data
index 3dc2b44..d29dff9 100644
--- a/test_data/of10/hello.data
+++ b/test_data/of10/hello.data
@@ -7,3 +7,5 @@
 -- c
 obj = of_hello_new(OF_VERSION_1_0);
 of_hello_xid_set(obj, 305419896);
+-- java
+builder.setXid(0x12345678)
diff --git a/test_data/of10/packet_in.data b/test_data/of10/packet_in.data
index 8168e3b..2cd98b0 100644
--- a/test_data/of10/packet_in.data
+++ b/test_data/of10/packet_in.data
@@ -27,3 +27,11 @@
 of_packet_in_reason_set(obj, 1);
 of_packet_in_total_len_set(obj, 9);
 of_packet_in_xid_set(obj, 305419896);
+-- java
+builder
+   .setXid(0x12345678)
+   .setBufferId(0xabcdef01)
+   .setTotalLen(9)
+   .setInPort(OFPort.LOCAL)
+   .setReason(OFPacketInReason.ACTION)
+   .setData(new byte[] { 0x61, 0x62, 0x63 } );