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📜 WAYPOINT LESSON

Checkpoint — Debugging & testing

⭐ beginner⏳ 20 min read📍 Lesson 69 of 85

A validator suite: implement the validators AND their discriminating tests — every contract asserted from both directions.

Checkpoint: the validator suite

Task: implement in Solution:

  1. static bool IsValidUsername(string s) — 3–20 chars, letters/digits/underscore only, non-null. (Use char.IsLetterOrDigit / '_'.)
  2. static int ParsePort(string input) — 1–65535 after parsing; FormatException for non-numeric, ArgumentOutOfRangeException for out-of-range, null → ArgumentException.
  3. static List<int> DedupeSorted(List<int> nums) — distinct values in ascending order; null/empty → empty list.