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- Samman learning hour: 5/5/10/25/5 outline; pairs stop at extracted method taking the lambda as a parameter - exercise/java: pre-factored variant of the kata (Q1/Q4 dead branch stripped, dates as constant), approval test red/flaky by design - exercise/solution: collectExpectedWeather(LongFunction<Boolean>) + no-arg overload; deterministic approval test (all-sunny lambda) - rehearse-with-agent.md: rehearsal setup with qwen + java-refactoring-mcp
38 lines
1.6 KiB
Markdown
38 lines
1.6 KiB
Markdown
# IceCreamForecasting — Split Loop 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 **Split Loop 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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