From 987fc30dd71883d0bcb068bbfa00c9235f3e36cb Mon Sep 17 00:00:00 2001
From: "Ruidy (aider)" <ruidy.nemausat@gmail.com>
Date: Mon, 2 Dec 2024 07:33:40 +0100
Subject: [PATCH] test: Add comprehensive test suite for Day 2 solution

---
 .../solutions/day02/day2_test.exs             | 57 +++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 test/advent_code2024/solutions/day02/day2_test.exs

diff --git a/test/advent_code2024/solutions/day02/day2_test.exs b/test/advent_code2024/solutions/day02/day2_test.exs
new file mode 100644
index 0000000..174f70a
--- /dev/null
+++ b/test/advent_code2024/solutions/day02/day2_test.exs
@@ -0,0 +1,57 @@
+defmodule AdventCode2024.Solutions.Day2Test do
+  use ExUnit.Case
+  alias AdventCode2024.Solutions.Day2
+
+  describe "solve/1" do
+    test "correctly identifies safe reports from example data" do
+      input = """
+      7 6 4 2 1
+      1 2 7 8 9
+      9 7 6 2 1
+      1 3 2 4 5
+      8 6 4 4 1
+      1 3 6 7 9
+      """
+
+      assert Day2.solve(input) == {:ok, 2}
+    end
+
+    test "identifies a single safe decreasing report" do
+      input = "7 6 4 2 1\n"
+      assert Day2.solve(input) == {:ok, 1}
+    end
+
+    test "identifies a single safe increasing report" do
+      input = "1 3 6 7 9\n"
+      assert Day2.solve(input) == {:ok, 1}
+    end
+
+    test "identifies an unsafe report with too large increase" do
+      input = "1 2 7 8 9\n"
+      assert Day2.solve(input) == {:ok, 0}
+    end
+
+    test "identifies an unsafe report with too large decrease" do
+      input = "9 7 6 2 1\n"
+      assert Day2.solve(input) == {:ok, 0}
+    end
+
+    test "identifies an unsafe report with direction change" do
+      input = "1 3 2 4 5\n"
+      assert Day2.solve(input) == {:ok, 0}
+    end
+
+    test "identifies an unsafe report with no change between numbers" do
+      input = "8 6 4 4 1\n"
+      assert Day2.solve(input) == {:ok, 0}
+    end
+
+    test "handles empty input" do
+      assert Day2.solve("") == {:error, :no_valid_reports}
+    end
+
+    test "handles invalid input format" do
+      assert Day2.solve("not numbers") == {:error, :invalid_format}
+    end
+  end
+end