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Cover image for Code Smell 244 - Incomplete Error information
Maxi Contieri
Maxi Contieri

Posted on • Originally published at

Code Smell 244 - Incomplete Error information

You show an error and provide no useful information

TL;DR: Help yourself and others with correction information


  • Debugging and maintenance challenge.

  • Fail Fast Principle violation

  • Debugging complex situations.


  1. Add all the relevant information to solve the solution


When you are reporting an error, either via an information text in the UI, by processing an API request, or by creating a test assertion, you need to provide an exit (a possible solution).

This is very relevant when dealing with complex scenarios, large objects, or arrays with minimal mistakes.

Sample Code


VALID_COLUMNS = ['name', 'gender', 'email']

def process_API_information(data):
    invalid_columns = []
    for column in data.keys():
        if column not in VALID_COLUMNS:

    assert not invalid_columns, "Invalid columns detected."  
    # No details were provided about which columns are invalid

data = {'name': 'John', 'gender': 'Pangender', 
        'age': 47, 'email': ''}
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VALID_COLUMNS = ['name', 'gender', 'email']

def process_API_information(data):
    invalid_columns = [
        column for column in data.keys() if column not in VALID_COLUMNS

    if invalid_columns:
        raise ValueError(
            f"Invalid columns detected: {', '.join(invalid_columns)}"
        )  # Shows WHICH columns are invalid

data = {'name': 'John', 'gender': 'Pangender', 
        'age': 47, 'email': ''}
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[X] Semi-Automatic

This is a semantic smell. You can warn the developers on error texts that do not include variables.


  • Errors


[X] Beginner

AI Assistants

AI assistants usually miss this kind of help and provide hardcoded error messages.


You need to always think about how to help your end users.

It might be yourself.



Code Smells are my opinion.


Photo by Brett Jordan on Unsplash

Information shared by an object might or might not be part of the structure of that object. That is, the object might compute the information, or it might delegate the request for information to another object.

Rebecca Wirfs Brooks

This article is part of the CodeSmell Series.

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