Exercism: RNA Transcription

readme.txt

# Rna Transcription

Write a program that, given a DNA strand, returns its RNA complement (per RNA transcription).

Both DNA and RNA strands are a sequence of nucleotides.

The four nucleotides found in DNA are adenine (**A**), cytosine (**C**),
guanine (**G**) and thymidine (**T**).

The four nucleotides found in RNA are adenine (**A**), cytosine (**C**),
guanine (**G**) and uracil (**U**).

Given a DNA strand, its transcribed RNA strand is formed by replacing
each nucleotide with its complement:

* `G` -> `C`
* `C` -> `G`
* `T` -> `A`
* `A` -> `U`


## Source

Rosalind [view source](http://rosalind.info/problems/rna)

complement.rb

module Complement
  DNA_TO_RNA_MAP = {
    'A' => 'U',
    'C' => 'G',
    'G' => 'C',
    'T' => 'A'
  }

  RNA_TO_DNA_MAP = DNA_TO_RNA_MAP.invert

  def self.of_dna(dna_strand)
    dna_strand.chars.inject('') { |rna_strand, base| rna_strand << DNA_TO_RNA_MAP[base] }
  end

  def self.of_rna(rna_strand)
    rna_strand.chars.inject('') { |dna_strand, base| dna_strand << RNA_TO_DNA_MAP[base] }
  end
end

complement_test.rb

require 'minitest/autorun'
require_relative 'complement'

class ComplementTest < MiniTest::Unit::TestCase
  def test_rna_complement_of_cytosine_is_guanine
    assert_equal 'G', Complement.of_dna('C')
  end

  def test_rna_complement_of_guanine_is_cytosine
    assert_equal 'C', Complement.of_dna('G')
  end

  def test_rna_complement_of_thymine_is_adenine
    assert_equal 'A', Complement.of_dna('T')
  end

  def test_rna_complement_of_adenine_is_uracil
    assert_equal 'U', Complement.of_dna('A')
  end

  def test_rna_complement
    assert_equal 'UGCACCAGAAUU', Complement.of_dna('ACGTGGTCTTAA')
  end

  def test_dna_complement_of_cytosine_is_guanine
    assert_equal 'G', Complement.of_rna('C')
  end

  def test_dna_complement_of_guanine_is_cytosine
    assert_equal 'C', Complement.of_rna('G')
  end

  def test_dna_complement_of_uracil_is_adenine
    assert_equal 'A', Complement.of_rna('U')
  end

  def test_dna_complement_of_adenine_is_thymine
    assert_equal 'T', Complement.of_rna('A')
  end

  def test_dna_complement
    assert_equal 'ACTTGGGCTGTAC', Complement.of_rna('UGAACCCGACAUG')
  end
end