Ryan Latta

How To Test A Ball of Mud

Are your unit tests hiding critical design flaws? Learn a two-pronged strategy to confidently refactor even the most tangled codebase.

How To Test A Ball of Mud
#1about 2 minutes

Defining the 'ball of mud' software problem

A 'ball of mud' codebase is too complex to understand and its changes have unpredictable results, requiring a different approach like testing to solve.

#2about 7 minutes

Using system tests to verify infrastructure stability

Simple system tests running frequently in CI can confirm infrastructure is operational, which is a critical first step before tackling code correctness.

#3about 4 minutes

Rebuilding testing skills with incremental unit tests

Start by adding two unit tests per work item to gradually build the team's testing skills and integrate testing into the development process.

#4about 3 minutes

Redefining the 'unit' in a complex codebase

The 'unit' in a unit test for a ball of mud is the smallest testable group of code, which reveals the actual system design, not an idealized one.

#5about 3 minutes

Weighing the risks and benefits of mocking

Mocking can ease the pain of dependencies but risks creating a shadow implementation; isolating dependencies by design is a more robust alternative.

#6about 3 minutes

Dealing with legacy tests and test dependencies

Old, failing tests should be deleted, and new tests must be independent to avoid creating a debugging nightmare where test order affects outcomes.

#7about 4 minutes

Strategies for ensuring test independence and speed

Enforce test independence by running tests in a random order and optimize speed by decoupling code from frameworks, not just through parallelization.

#8about 3 minutes

Adding smoke tests for critical application use cases

Once infrastructure and unit tests are in place, add smoke tests for critical use cases to verify high-level application correctness.

#9about 11 minutes

Conclusion and Q&A on advanced testing topics

The talk concludes by summarizing the need for a different approach to legacy code, followed by a Q&A on singletons, snapshot testing, and parameterized tests.

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Designer

Andrew Comp

Andrew Comp
Berlin, Germany

Intermediate
Java
JavaScript

Matching moments

Practical strategies for testing legacy applications
02:02 MIN

Practical strategies for testing legacy applications

Testing .NET applications a Tool box for every developer

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The vicious cycle of untestable legacy code
02:52 MIN

The vicious cycle of untestable legacy code

How Unit Testing Saved My Career

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Shifting focus from fixing the test to fixing the app
01:50 MIN

Shifting focus from fixing the test to fixing the app

Fighting test flakiness with time machines

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Why standard TDD fails in complex legacy code
06:29 MIN

Why standard TDD fails in complex legacy code

How to TDD in legacy code

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Enforcing architectural patterns with automated tests
06:32 MIN

Enforcing architectural patterns with automated tests

One-click-to-production: Test and automate your application

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Identifying the common pains of software testing
09:16 MIN

Identifying the common pains of software testing

Write tests you love, not hate

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Why traditional testing methods fail for microservice architectures
04:45 MIN

Why traditional testing methods fail for microservice architectures

Lessons from Our API Past: Evolving to a Resilient API Future

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Preventing architectural decay and code structure issues
03:37 MIN

Preventing architectural decay and code structure issues

Antipatterns - nemesis of software development

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