test: fix tests

Author: vkarpov15

lib/schema.js

@@ -1739,7 +1739,9 @@ Schema.prototype.interpretAsType = function(path, obj, options) {
       'https://bit.ly/mongoose-schematypes for a list of valid schema types.');
   }
 
-  obj.parentSchema = this;
+  if (name === 'Union') {
+    obj.parentSchema = this;
+  }
   const schemaType = new MongooseTypes[name](path, obj, options);
 
   if (schemaType.$isSchemaMap) {

lib/schema/union.js

@@ -4,10 +4,8 @@
  * ignore
  */
 
-const MongooseMap = require('../types/map');
 const SchemaUnionOptions = require('../options/schemaUnionOptions');
 const SchemaType = require('../schemaType');
-const createJSONSchemaTypeDefinition = require('../helpers/createJSONSchemaTypeDefinition');
 
 const firstValueSymbol = Symbol('firstValue');
 
@@ -16,7 +14,7 @@ const firstValueSymbol = Symbol('firstValue');
  */
 
 class Union extends SchemaType {
-  constructor(key, options, schemaOptions) {
+  constructor(key, options, schemaOptions = {}) {
     super(key, options, 'Union');
     if (!options || !Array.isArray(options.of) || options.of.length === 0) {
       throw new Error('Union schema type requires an array of types');

test/schematype.test.js

@@ -266,7 +266,7 @@ describe('schematype', function() {
     });
 
     const typesToTest = Object.values(mongoose.SchemaTypes).
-      filter(t => t.name !== 'SchemaSubdocument' && t.name !== 'SchemaDocumentArray');
+      filter(t => t.name !== 'SchemaSubdocument' && t.name !== 'SchemaDocumentArray' && t.name !== 'Union');
 
     typesToTest.forEach((type) => {
       it(type.name + ', when given a default option, set its', () => {