Day 49: Writing Code Without Tests

 

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🐍 Python Mistakes Everyone Makes ❌

Day 49: Writing Code Without Tests

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❌ The Mistake

Writing features and logic without any tests and assuming the code “just works”.

def add(a, b): 

    return a + b

Looks fine… until it’s used incorrectly.

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❌ What Goes Wrong?

• Bugs go unnoticed

• Changes break existing functionality

• Fear of refactoring

• Manual testing becomes repetitive

• Production issues appear unexpectedly

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✅ The Correct Way

Write simple tests to verify behavior.

def test_add():
    assert add(2, 3) == 5 

    assert add(-1, 1) == 0

Even basic tests catch problems early.

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❌ Why This Fails? (Main Points)

• No safety net for changes

• Bugs discovered too late

• Hard to refactor confidently

• Code behavior is undocumented

• Debugging takes longer

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🧠 Simple Rule to Remember

🧠 If it’s important, test it
🧠 Tests are documentation
🧠 Untested code is broken code waiting to happen

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🚀 Final Takeaway

Tests don’t slow you down —
they save time, prevent regressions, and build confidence.

Even one test is better than none.