fix: add cause prop to exception (#60)

Author: gxcsoccer

lib/exception.js

@@ -57,6 +57,10 @@ module.exports = function toException(err, className) {
         '$class': '[java.lang.StackTraceElement',
         '$': stackTraceElements,
       },
+      cause: {
+        '$class': 'java.lang.Throwable',
+        '$': null,
+      },
     },
   };
 };

test/exception.test.js

@@ -17,6 +17,8 @@ describe('js error to java exception', function() {
     exception.$.stackTrace.$.forEach(function(ele) {
       assert.equal(ele.$class, 'java.lang.StackTraceElement');
     });
+    assert.equal(exception.$.cause.$class, 'java.lang.Throwable');
+    assert(exception.$.cause.$ === null);
     // console.log(JSON.stringify(exception, null, 2));
   });
 
@@ -29,6 +31,8 @@ describe('js error to java exception', function() {
     exception.$.stackTrace.$.forEach(function(ele) {
       assert.equal(ele.$class, 'java.lang.StackTraceElement');
     });
+    assert.equal(exception.$.cause.$class, 'java.lang.Throwable');
+    assert(exception.$.cause.$ === null);
     // console.log(JSON.stringify(exception, null, 2));
   });
 });