You assert that something happened, but why? TL;DR: Be explicit when creating tests to ensure clarity and maintainability Problems Readability
Coupling to external databases, global state or singletons, static methods, or external services
Maintenance Difficulty
Debugging Complexity
Hidden Dependencies Solutions Be Explicit
Inline the setup
Use dependency Injection
Use mocking with caution Context Your test depends on external data or configurations not immediately visible within the test itself. This obscures the test’s setup, making it difficult for someone reading it to understand what is being tested and why it might fail. Every test case should have three stages: Setup: Initialize and configure everything needed for the test.
Exercise: Execute the code being tested.
Assert: Verify the expected outcome. All of them must be explicit. Sample Code Wrong @Test
void shouldReturnAnswerWhenAnswerExists() {
    User answer = KnowledgeRepository.findAnswerToQuestion(42);
    assertNotNull(answer);
} Right @Test
void shouldReturnAnswerWhenAnswerExists() {
    KnowledgeRepository knowledgeRepository = 
        new InMemoryKnowledgeRepository();
    Answer expectedAnswer = new Answer(42, "The Ultimate");
    knowledgeRepository.save(expectedAnswer);
    
    Answer actualAnswer = answerRepository.findAnswerToQuestion(42);
    assertNotNull(actualAnswer);
    assertEquals(expectedAnswer, actualAnswer);
} Detection [x] Manual You can detect this smell by looking for tests that do not clearly show their setup steps or rely heavily on external configurations. Tags Test Smells Level [x]Intermediate AI Generation AI-generated code often avoids this smell due to the tendency to create small, isolated examples. AI Detection Most AI Detectors fail to identify this as a problem unless you point it out explicitly. Conclusion This code smell is especially prevalent in legacy codebases or when consistent testing practices are lacking. You need to be explicit about the environment since tests must always be in "full environmental control." Relations Code Smell 17 - Global Functions Code Smell 32 - Singletons Code Smell 18 - Static Functions Code Smell 30 - Mocking Business More Info Craft Better Software Coupling - The one and only software design problem Disclaimer Code Smells are my opinion. Credits Photo by Brands&People on Unsplash Science is what we understand well enough to explain to a computer, Art is all the rest Donald Knuth https://hackernoon.com/400-thought-provoking-software-engineering-quotes?embedable=true This article is part of the CodeSmell Series. https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-i-xqz3evd?embedable=true You assert that something happened, but why? You assert that something happened, but why? TL;DR: Be explicit when creating tests to ensure clarity and maintainability TL;DR: Be explicit when creating tests to ensure clarity and maintainability Problems Readability Coupling to external databases, global state or singletons, static methods, or external services Maintenance Difficulty Debugging Complexity Hidden Dependencies Readability Coupling to external databases, global state or singletons , static methods , or external services Coupling singletons static methods Maintenance Difficulty Debugging Complexity Hidden Dependencies Solutions Be Explicit Inline the setup Use dependency Injection Use mocking with caution Be Explicit Inline the setup Use dependency Injection Use mocking with caution mocking Context Your test depends on external data or configurations not immediately visible within the test itself. This obscures the test’s setup, making it difficult for someone reading it to understand what is being tested and why it might fail. Every test case should have three stages: Setup: Initialize and configure everything needed for the test. Exercise: Execute the code being tested. Assert: Verify the expected outcome. Setup: Initialize and configure everything needed for the test. Exercise: Execute the code being tested. Assert: Verify the expected outcome. All of them must be explicit. Sample Code Wrong @Test
void shouldReturnAnswerWhenAnswerExists() {
    User answer = KnowledgeRepository.findAnswerToQuestion(42);
    assertNotNull(answer);
} @Test
void shouldReturnAnswerWhenAnswerExists() {
    User answer = KnowledgeRepository.findAnswerToQuestion(42);
    assertNotNull(answer);
} Right @Test
void shouldReturnAnswerWhenAnswerExists() {
    KnowledgeRepository knowledgeRepository = 
        new InMemoryKnowledgeRepository();
    Answer expectedAnswer = new Answer(42, "The Ultimate");
    knowledgeRepository.save(expectedAnswer);
    
    Answer actualAnswer = answerRepository.findAnswerToQuestion(42);
    assertNotNull(actualAnswer);
    assertEquals(expectedAnswer, actualAnswer);
} @Test
void shouldReturnAnswerWhenAnswerExists() {
    KnowledgeRepository knowledgeRepository = 
        new InMemoryKnowledgeRepository();
    Answer expectedAnswer = new Answer(42, "The Ultimate");
    knowledgeRepository.save(expectedAnswer);
    
    Answer actualAnswer = answerRepository.findAnswerToQuestion(42);
    assertNotNull(actualAnswer);
    assertEquals(expectedAnswer, actualAnswer);
} Detection [x] Manual [x] Manual [x] You can detect this smell by looking for tests that do not clearly show their setup steps or rely heavily on external configurations. Tags Test Smells Test Smells Level [x]Intermediate [x] Intermediate [x] AI Generation AI-generated code often avoids this smell due to the tendency to create small, isolated examples. AI Detection Most AI Detectors fail to identify this as a problem unless you point it out explicitly. Conclusion This code smell is especially prevalent in legacy codebases or when consistent testing practices are lacking. You need to be explicit about the environment since tests must always be in "full environmental control." Relations Code Smell 17 - Global Functions Code Smell 17 - Global Functions Code Smell 32 - Singletons Code Smell 32 - Singletons Code Smell 18 - Static Functions Code Smell 18 - Static Functions Code Smell 30 - Mocking Business Code Smell 30 - Mocking Business More Info Craft Better Software Craft Better Software Coupling - The one and only software design problem Coupling - The one and only software design problem Disclaimer Code Smells are my opinion . opinion Credits Photo by Brands&People on Unsplash Brands&People Unsplash Science is what we understand well enough to explain to a computer, Art is all the rest Science is what we understand well enough to explain to a computer, Art is all the rest Donald Knuth Donald Knuth https://hackernoon.com/400-thought-provoking-software-engineering-quotes?embedable=true https://hackernoon.com/400-thought-provoking-software-engineering-quotes?embedable=true This article is part of the CodeSmell Series. https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-i-xqz3evd?embedable=true https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-i-xqz3evd?embedable=true

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