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38 lines
1.4 KiB
Markdown
38 lines
1.4 KiB
Markdown
# Kata 13: The Filesystem-Agnostic Config Loader
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**Target Idioms:** `io/fs` abstraction, `fs.WalkDir`, Testability via `fstest.MapFS`, `embed` readiness
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**Difficulty:** 🟡 Intermediate
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## 🧠 The "Why"
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In Go, passing `"/etc/app/config"` all over the place hard-couples your logic to the OS.
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Idiomatic Go uses `fs.FS` so you can:
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- load from disk,
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- load from embedded files,
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- load from a ZIP filesystem,
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- unit test without touching the real filesystem.
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## 🎯 The Scenario
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Your CLI loads configuration fragments from a directory tree, merges them, and prints a final config report.
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## 🛠 The Challenge
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Implement:
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- `func LoadConfigs(fsys fs.FS, root string) (map[string][]byte, error)`
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### 1. Functional Requirements
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- [ ] Walk `root` recursively and read all `*.conf` files.
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- [ ] Return a map of `path -> content`.
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- [ ] Reject invalid paths cleanly.
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### 2. The "Idiomatic" Constraints (Pass/Fail Criteria)
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- [ ] **Must** accept `fs.FS` (not `os` paths) in the core API.
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- [ ] **Must** use `fs.WalkDir` and `fs.ReadFile`.
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- [ ] **Must NOT** use `os.Open` / `filepath.Walk` inside the core loader.
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- [ ] Unit tests must use `testing/fstest.MapFS`.
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## 🧪 Self-Correction (Test Yourself)
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- **If you can’t test without real files:** you failed.
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- **If your loader only works on disk:** you failed the abstraction goal.
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## 📚 Resources
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- https://pkg.go.dev/io/fs
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- https://go.dev/src/embed/embed.go
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