RNA transcription solution

Author: eprunier

rna-transcription/README.md

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+# Rna Transcription
+
+Given a DNA strand, return 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 thymine (**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`
+
+## Setup
+
+Go through the setup instructions for JavaScript to
+install the necessary dependencies:
+
+http://exercism.io/languages/javascript
+
+## Making the Test Suite Pass
+
+Execute the tests with:
+
+    jasmine-node .
+
+In many test suites all but the first test have been skipped.
+
+Once you get a test passing, you can unskip the next one by
+changing `xit` to `it`.
+
+## Source
+
+Rosalind [http://rosalind.info/problems/rna](http://rosalind.info/problems/rna)
+
+## Submitting Incomplete Problems
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.
+

rna-transcription/rna-transcription.js

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+const DnaTranscriber = function () {};
+
+const convTable = {
+	"G": "C",
+	"C": "G",
+	"T": "A",
+	"A": "U"
+};
+
+DnaTranscriber.prototype.toRna = function (dna) {
+	return Array
+		.from(dna)
+		.map(nucleotide => {
+			const rnaNucleotide = convTable[nucleotide];
+			if (rnaNucleotide) {
+				return rnaNucleotide;
+			} else {
+				throw new Error('Invalid input');
+			}
+		}).join('');
+};
+
+module.exports = DnaTranscriber;

rna-transcription/rna-transcription.spec.js

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+var DnaTranscriber = require('./rna-transcription');
+var dnaTranscriber = new DnaTranscriber();
+
+describe('toRna()', function() {
+
+  it('transcribes cytosine to guanine', function() {
+    expect(dnaTranscriber.toRna('C')).toEqual('G');
+  });
+
+  it('transcribes guanine to cytosine', function() {
+    expect(dnaTranscriber.toRna('G')).toEqual('C');
+  });
+
+  it('transcribes adenine to uracil', function() {
+    expect(dnaTranscriber.toRna('A')).toEqual('U');
+  });
+
+  it('transcribes thymine to adenine', function() {
+    expect(dnaTranscriber.toRna('T')).toEqual('A');
+  });
+
+  it('transcribes all dna nucleotides to their rna complements', function() {
+    expect(dnaTranscriber.toRna('ACGTGGTCTTAA'))
+        .toEqual('UGCACCAGAAUU');
+  });
+
+  it('correctly handles completely invalid input', function () {
+     expect(function () { dnaTranscriber.toRna('XXX') }).toThrow(
+          new Error('Invalid input')
+      );
+  });
+
+  it('correctly handles partially invalid input', function () {
+      expect(function () { dnaTranscriber.toRna('ACGTXXXCTTAA') }).toThrow(
+          new Error('Invalid input')
+      );
+  });
+});