defmodule NucleotideCountTest do
  use ExUnit.Case

  describe "count" do
    test "empty dna string has no adenine" do
      assert NucleotideCount.count(~c"", ?A) == 0
    end

    test "one nucleotide" do
      assert NucleotideCount.count(~c"G", ?G) == 1
    end

    test "repetitive cytosine gets counted" do
      assert NucleotideCount.count(~c"CCCCC", ?C) == 5
    end

    test "counts only thymine" do
      assert NucleotideCount.count(~c"GGGGGTAACCCGG", ?T) == 1
    end
  end

  describe "histogram" do
    test "empty dna string has no nucleotides" do
      expected = %{?A => 0, ?T => 0, ?C => 0, ?G => 0}
      assert NucleotideCount.histogram(~c"") == expected
    end

    test "one nucleotide" do
      expected = %{?A => 0, ?T => 0, ?C => 0, ?G => 1}
      assert NucleotideCount.histogram(~c"G") == expected
    end

    test "repetitive sequence has only guanine" do
      expected = %{?A => 0, ?T => 0, ?C => 0, ?G => 8}
      assert NucleotideCount.histogram(~c"GGGGGGGG") == expected
    end

    test "counts all nucleotides" do
      s = ~c"AGCTTTTCATTCTGACTGCAACGGGCAATATGTCTCTGTGTGGATTAAAAAAAGAGTGTCTGATAGCAGC"
      expected = %{?A => 20, ?T => 21, ?C => 12, ?G => 17}
      assert NucleotideCount.histogram(s) == expected
    end
  end
end