Mocha测试在失败时执行两次回调

I have a simple Mongoose schema that I'm testing with Mocha; when I run the test with 'success' callback it executes normally, however when the last test executes it fails and appears to run the test again (I get two conclusions, one which populates the error object and the second one which returns null in the error object.) Running the two tests below results in the following output:I have a simple Mongoose schema that I'm testin