test: Add tests for MedicalTranscription.Utilities

lib/medical_transcription/utilities.ex

@@ -14,6 +14,7 @@ defmodule MedicalTranscription.Utilities do
     end)
   end
 
+  @doc "Takes the output of `tally/1` and returns a string representation."
   def tally_to_string(tallied_enumerable) do
     tallied_enumerable
     |> Enum.map_join(", ", fn {key, value} -> "#{key} (#{value})" end)

test/medical_transcription/utilities_test.exs

@@ -0,0 +1,28 @@
+defmodule MedicalTranscription.UtilitiesTest do
+  use ExUnit.Case, async: true
+  alias MedicalTranscription.Utilities
+
+  describe "tally/1" do
+    test "it counts elements in an enumerable of atoms" do
+      input = [:one, :two, :three, :two, :two, :one]
+
+      assert Utilities.tally(input) == %{
+               one: 2,
+               two: 3,
+               three: 1
+             }
+    end
+  end
+
+  describe "tally_to_string/1" do
+    test "it formats a string version of the output of `tally/1`" do
+      input = %{
+        one: 2,
+        two: 3,
+        three: 1
+      }
+
+      assert Utilities.tally_to_string(input) == "one (2), two (3), three (1)"
+    end
+  end
+end