Test handling of undefined configuration

query/view/boost_sources_and_layers.js

@@ -24,6 +24,9 @@ function generateTermQuery(field, value, boost) {
 
 module.exports = function( configuration ) {
   return function( ) {
+    if (!configuration) {
+      return null;
+    }
     const filters = [];
     ['source', 'layer'].forEach(function(target) {
       if (configuration[target]) {

test/unit/query/view/boost_sources_and_layers.js

@@ -9,6 +9,13 @@ module.exports.tests.empty_config = function(test, common) {
     t.equal(query, null, 'query is empty');
     t.end();
   });
+
+  test('undefined configuration returns empty query', function(t) {
+    const view_instance = boost_sources_and_layers(undefined);
+    const query = view_instance();
+    t.equal(query, null, 'query is empty');
+    t.end();
+  });
 };
 
 module.exports.tests.single_item_config = function(test, common) {