create stackTraceLine helper to debug predicates

helper/stackTraceLine.js

@@ -0,0 +1,13 @@
+'use strict';
+
+module.exports = () => {
+  const stack = new Error().stack.split('\n');
+  let targetLine;
+
+  stack.forEach((line) => {
+    if(line.indexOf('at controller') !== -1) {
+      targetLine = line.trim();
+    }
+  });
+  return targetLine;
+};

test/unit/helper/stackTraceLine.js

@@ -0,0 +1,20 @@
+const stackTraceLine = require('../../../helper/stackTraceLine');
+
+module.exports.tests = {};
+module.exports.tests.stackTrace = (test, common) => {
+  test('No exceptions thrown when function is called', (t) => {
+    t.doesNotThrow(stackTraceLine, 'No exceptions thrown');
+    t.end();
+  });
+};
+
+module.exports.all = function (tape, common) {
+
+  function test(name, testFunction) {
+    return tape('[helper] stackTraceLine: ' + name, testFunction);
+  }
+
+  for( var testCase in module.exports.tests ){
+    module.exports.tests[testCase](test, common);
+  }
+};

test/unit/run.js

@@ -35,6 +35,7 @@ var tests = [
   require('./helper/logging'),
   require('./helper/type_mapping'),
   require('./helper/sizeCalculator'),
+  require('./helper/stackTraceLine'),
   require('./middleware/access_log'),
   require('./middleware/accuracy'),
   require('./middleware/assignLabels'),