Add specs to day1 as a test for allowing TDD

day1/day1.cr

@@ -48,6 +48,8 @@ class Day1
     end
 end
 
-day1 = Day1.new(File.read("input.txt"))
-puts "1A: #{day1.part_a}"
-puts "1B: #{day1.part_b}"
+unless PROGRAM_NAME.includes?("crystal-run-spec")
+    day1 = Day1.new(File.read("input.txt"))
+    puts "1A: #{day1.part_a}"
+    puts "1B: #{day1.part_b}"
+end

day1/spec/day1_spec.cr

@@ -0,0 +1,33 @@
+require "../day1"
+require "spec"
+
+describe Day1 do
+    describe "#part_a" do
+        it "works correctly for sample input" do
+            input = <<-SAMPLE
+            +1
+            -2
+            +3
+            +1
+            SAMPLE
+            day1 = Day1.new(input)
+
+            day1.part_a.should eq 3 
+        end
+    end
+
+    describe "#part_b" do
+        it "works correctly for sample input" do
+            sample_inputs_with_expected_outputs = {
+                "+1, -1" => 0,
+                "+3, +3, +4, -2, -4" => 10,
+                "-6, +3, +8, +5, -6" => 5,
+                "+7, +7, -2, -7, -4" => 14
+            }
+            sample_inputs_with_expected_outputs.each do |input_str, expected_output|
+                day1 = Day1.new(input_str.gsub(", ", "\n"))
+                day1.part_b.should eq expected_output
+            end
+        end
+    end
+end