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README.md

TDD vs? Interactive and Literate Programming?

Contrast these paradigms and discuss how the complement each other.

Intro

Observation:

  • Both TDD and IP/LP focus on immediate feedback to support the dev process
  • IP/LP is very natural in the sense that I can literally translate my thoughts into code and see what happens
  • TDD wants me to think one step ahead
    • In some domains, this can be really hard
    • Depends on level of abstraction
  • For me it is sometimes difficult to smoothly transition between these paradigms

Questions to discuss:

  • In what regards are TDD and IP/LP similar and different?
  • How can these styles complement each other?
  • In which scenarios would you follow which paradigm?
  • ...

Demo on IP and LP

We agree early on that it is not an either or question but rather about contrasting the approaches.

IP/LP

Use cases

  • Exploration
    • What to I want?
    • What is relevant?
    • What is it that I really want to implement (later)?
  • Support and document learning process

Observations

  • Always inside out
  • Possibly one-off product that we throw away later
  • IP/LP tools like notebooks offer interesting ways to understand source code and domains (using animations, sliders, ...)

TDD

Observations

  • Less interactive
  • Can use a red test to approximate the expected outcome (this bears some similarity to IP)
  • Tests can use documentation language to describe their purpose
  • Can be outside-in
  • Sometimes TDD is not possible, then
    • Regression test
    • Additional assertions on demand
    • Is it possible to derive properties that we can test against?

Documentation Language

We observe that documentation language, i.e. easy-to-understand explanations are a common theme in other tools as well because this is useful. Examples:

Claus' Procedure for "IP/LP to TDD"

Once exploration is over, I want to transition from IP/LP to TDD. This is how I do it:

  1. Derive trusted source code
  • We trust it because we sufficiently inspected and validated results
  1. Derive regression tests using artifacts generated by our code
  • Freeze behavior
  • Pave way for automated tests
  1. Refactor both source code and interactive inspection tools
  2. Continue

Links

Wiki

Tools

Recommended Talks by Bret Victor