Errors from Result will now contain the caller stack trace

src/v1/result.js

@@ -45,6 +45,7 @@ class Result {
    * @param {ConnectionHolder} connectionHolder - to be notified when result is either fully consumed or error happened.
    */
   constructor(streamObserver, statement, parameters, metaSupplier, connectionHolder) {
+    this._stack = (new Error('')).stack.substr(6); // we don't need the 'Error\n' part
     this._streamObserver = streamObserver;
     this._p = null;
     this._statement = statement;
@@ -137,6 +138,9 @@ class Result {
       // notify connection holder that the used connection is not needed any more because error happened
       // and result can't bee consumed any further; call the original onError callback after that
       self._connectionHolder.releaseConnection().then(() => {
+        // Error.prototype.toString() concatenates error.name and error.message nicely
+        // then we add the rest of the stack trace
+        error.stack = error.toString() + '\n' + this._stack;
         onErrorOriginal.call(observer, error);
       });
     };

test/v1/result.test.js

@@ -72,4 +72,27 @@ describe('result stream', () => {
       }
     });
   });
+
+  it('should have a stack trace that contains code outside the driver calls', done => {
+    // Given
+    const fn_a = cb => fn_b(cb);
+    const fn_b = cb => fn_c(cb);
+    const fn_c = cb => session.run('RETURN 1/0 AS x').catch(cb);
+
+    // When
+    fn_a(err => {
+      const stack = err.stack;
+
+      // Then
+      const contains_fn_a = /at fn_a \(.*?\/result.test.js:\d+:\d+\)/.test(stack);
+      const contains_fn_b = /at fn_b \(.*?\/result.test.js:\d+:\d+\)/.test(stack);
+      const contains_fn_c = /at fn_c \(.*?\/result.test.js:\d+:\d+\)/.test(stack);
+
+      expect(contains_fn_a).toBeTruthy();
+      expect(contains_fn_b).toBeTruthy();
+      expect(contains_fn_c).toBeTruthy();
+
+      done();
+    });
+  });
 });