test: Add test input fixture for Day1 solution

test/advent_code2024_test.exs

@@ -2,11 +2,30 @@ defmodule AdventCode2024Test do
   use ExUnit.Case
   doctest AdventCode2024
 
+  @test_input "test/fixtures/day1/input.txt"
+
+  setup do
+    # Ensure the fixtures directory exists
+    File.mkdir_p!("test/fixtures/day1")
+    
+    # Create test input file
+    test_content = """
+    1 2
+    3 4
+    5 6
+    """
+    File.write!(@test_input, test_content)
+
+    on_exit(fn ->
+      File.rm!(@test_input)
+    end)
+  end
+
   test "delegates day1 solutions to Day1 module" do
-    assert {:ok, result} = AdventCode2024.solve_day1()
+    assert {:ok, result} = AdventCode2024.solve_day1(@test_input)
     assert is_integer(result)
     
-    assert {:ok, result} = AdventCode2024.solve_day1_part2() 
+    assert {:ok, result} = AdventCode2024.solve_day1_part2(@test_input)
     assert is_integer(result)
   end
 end