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The refactoring is now published as Slice on sammancoaching.org: https://sammancoaching.org/refactorings/slice.html - git mv ideas/split-loop-with-lambda -> ideas/slice-with-lambda - rename learning-hour file and update frontmatter name - update paths in tools/rehearse scripts and report title - update prose: 'Split Loop with Lambda' -> 'Slice with Lambda' in learning hour, exercise READMEs, storyboard, solution comments - link the published Slice refactoring from the pattern draft
38 lines
1.6 KiB
Markdown
38 lines
1.6 KiB
Markdown
# IceCreamForecasting — Slice with Lambda (exercise)
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Pre-factored variant of [IceCreamForecasting-Refactoring-Kata](https://github.com/emilybache/IceCreamForecasting-Refactoring-Kata):
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the Q1/Q4 dead branch is stripped and the hardcoded dates are a constant now.
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Everything else — including the noise in the scoring loop — is untouched.
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## Task
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`longRangeForecast()` is hard to test: it calls `scorer`, and `Scorer`
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stands for an external weather service you must not call from a unit test.
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The rest of the method's inputs are only `DATES` and `ANCHOR_DATE`.
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Get it under test:
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1. First get any test running that calls `longRangeForecast()` —
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it will fail or be flaky, because of the dependency on `Scorer`.
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2. Then use the **Slice with Lambda** mechanics (6 steps, on the handout)
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so that the weather collection becomes an extracted method that takes the
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weather-reading as a **lambda parameter**.
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3. Stop when you have an extracted method that takes the lambda as a parameter,
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and a test that passes **without** touching `Scorer`.
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## Constraint
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Don't change `Scorer` and don't change the *behaviour* of
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`longRangeForecast()`. Compile early, compile often.
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## Debrief questions
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- At which step did plain **Split Loop** stop working, and why?
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(Hint: what type did your introduced variable end up being?)
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- There are **two** calls to `scorer` in the weather loop.
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What did you do with each one?
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- Could you delete either call without changing the forecast?
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Try it. Why did that work?
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- Where would you take this next — more extraction, or moving the method
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to another class where `Scorer` is unknown?
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