Strategic Test Driven Development

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Strategic Test-driven Development

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Francesco Strazzullo (AKA Strazz) @TheStrazz86 (Follow me on Twitter!) Ego Slide

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https://www.apress.com/it/book/9781484249666 Use “TheStrazz” discount code

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What is Test-driven Development?

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Write a failing test Write code to pass that test Refactor keeping the test green

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Test Driven Development

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How can Development be driven by Tests?

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Write a failing test Write code to pass that test Refactor keeping the test green

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A Big Decision is hidden in plain sight

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What is the next test to write?

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“Software development is a learning process, working code is a side eﬀect. If that’s true… how can we maximize learning?” Alberto Brandolini

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Write the test that lets you learn the most about the problem

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Write the test that lets you reach your goal as fast as possible

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Write a test that lets you approach the goal Write code to pass that test Refactor keeping the test green

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Another Big Decision is hidden in plain sight

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Write just the code that you need to pass the new test

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Write a test that lets you approach the goal Write just the code needed to pass that test Refactor keeping the test green

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Your Design emerges from tests

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TDD is a goal oriented decision-making tool based on tests

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Test Driven Development

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What is a Test?

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“Tests are just one form of feedback” Kent Beck

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Feedback Driven Development

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Define a feedback that lets you approach the goal Build something “small” Validate your code with “fast” feedbacks

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TDD is a goal oriented decision-making tool based on feedbacks

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Goal Small Outcome Feedback

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What kind of decisions can you make with TDD?

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Strategic long term decisions Tactical put strategy into action Operational made daily

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How to use TDD “mindset” for Tactical or Strategic Decisions?

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Choosing the next feature

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Impact Mapping

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Graph by Susanna Ferrario

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Choose the impact that you believe will help the most to reach the goal Build a small deliverable Use Metrics to validate your assumptions

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Software Architecture

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What is the goal of Software Architecture?

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Non-functional Requirements

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“A non-functional requirement (NFR) is a requirement that specifies criteria that can be used to judge the operation of a system, rather than specific behaviors.” Wikipedia

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accessibility accountability accuracy adaptability reliability administrability affordability agility auditability responsiveness autonomy availability compatibility composability seamlessness configurability correctness credibility customizability simplicity debugability self-sustainability robustness dependability sustainability deployability determinability discoverability distributability usability durability effectiveness efficiency extensibility repeatability fault tolerance fidelity flexibility inspectability reusability reproducibility integrity interoperability learnability securability maintainability manageability mobility modifiability stability modularity operability evolvability performances tailorability portability precision predictability resilience transparency producibility safety recoverability relevance testability

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What are the feedback for Software Architecture?

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Fitness Functions

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What is a “small outcome” for Software Architecture?

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Walking Skeleton

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“A Walking Skeleton is a tiny implementation of the system that performs a small end-to-end function. It need not use the final architecture, but it should link together the main architectural components. The architecture and the functionality can then evolve in parallel.” Alistair Cockburn

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Define a set of NFRs to check with fitness functions Build a “walking skeleton” Evolve architecture with fitness functions

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We should build this software?

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What kind of feedback do we need?

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User Research

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Define your idea Small Outcome Use User Feedbacks to validate your idea

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Strategic Operational Tactical

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Goal Small Outcome Feedback

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In a nutshell...

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Learn the rules of the tool Find the principles that are hidden in the tool Explore interrelationships between tools