Node.js learning summary: Methods of debugging code_node.js

Foreword

Have you ever felt like there was a ghost in the world when you were debugging a certain piece of code?

Have you ever felt that when debugging an API, there was a problem with calling a third-party interface or incorrect documentation?

Have you ever been debugging a bug and always felt that the source of the problem was the wrong way of using it?

Have you ever felt that when installing a service, the documentation or environment did not match the requirements?

Believe in the process and methods, and don’t be misled by the results.............

Overview

Debugging code is often similar to investigating a case, but the importance of the results is different. The police investigate cases for the sake of the stability of the people, while we debug for the stability of the system. In this case, we should not accuse any piece of code or program unjustly, lest they receive unreasonable punishment.

Some of the following process methods come from personal summary. From a personal perspective, some of the previous methods are accumulated through long-term experience. Of course, they are more theoretical in reference, but as a personal method, they may be more Suitable for DS like me.

Test method

Code procedural debugging method

The first thing to pay attention to when debugging code is the process. You must clarify the ideas that lead to the final result, that is, the process of committing the crime. You can get the result of the crime from the step-by-step follow-up in the process of committing the crime. During the analysis of the crime process, every suspicious point must be marked (that is, the log information mentioned in the code). After such an analysis process, black box testing is performed, inputs are added, and the results are verified. Finally, verify your judgment based on the marks at each step to find the reason.

The above solution is a procedural adjustment method. The advantages of this method are self-evident. You can directly analyze the entire process through a test. However, this method is very time-consuming. It is okay to clarify your own code logic, but it is necessary to clarify other people's logic codes. It is difficult to reach the sky.

Unit test debugging method

The basic purpose of unit testing is to ensure the normal operation of a certain function, class or functional module, including testing and verification of abnormal situations. As a programmer, the favorite verification method is "piling" (piling means providing false default data). This method is very convenient to adjust, but one disadvantage is that it cannot be used again, because after we verify that it is normal, , many developers will comment or delete it, so if we complete the development in the development environment, but we want to verify it in the test environment, we must re-write a piece of piling logic. So, looking at it this way, when it comes to the live network, then It will be more troublesome. Since there is so much inconvenience, you can try the following.

Add a unit test class. This class needs to control its permissions. It can only be executed through background login or command line. The function of this class is to detect the key logic of the system and make corresponding test output results. . We must believe that all interface classes can be tested through unit test classes. Many times programmers question, should we do this? In fact, we really need to do it. After all, many tests are now done as black box tests.

This debugging method is suitable for the development process and can ensure that our current network code runs normally after it is released. I hope everyone will incorporate this process into the development stage when planning development time.

Quick positioning method

Are the first two complicated processes too idealistic? My code is only 100 lines, and the system is not complicated. If this is the case, then quickly perform positioning analysis. We often encounter

1. The input is normal and the output is abnormal;

2. The input is normal, the logic is abnormal, and the output is abnormal;

3. The input is abnormal, the logic is normal, and the output is normal;

4. Input is abnormal, logic is abnormal, and output is none.

In my personal development process, I often encounter some of the above types of problems. For example, during the development of Node.js, I encounter string.length prompts that string does not have a length method. At that time, I was confused and asked myself, why do other strings have a length method, why not this one? Many students should know that the problem is that this string is not a string at all. It just means that you have idealized it into a string, which means that there is something wrong with what you input. So the best way to locate this problem is to print the input and print the output.

Maybe other programs are not so simple, but the most basic thing is to judge the input and output of functions that encounter exceptions in the main function, so that they can be quickly located.

Remember: Don’t take quotes out of context and think so.

The above methods and processes are only summarized based on PHP or Node.js. There may be similarities or differences for C & C. If you don’t like it, don’t spray it, just watch and cherish it.