Add tests for ncbi module

tests/test_ncbi.py

+"""
+Tests for the mutalyzer.ncbi module.
+"""
+
+
+from __future__ import unicode_literals
+
+import pytest
+
+from mutalyzer import ncbi
+
+
+pytestmark = [
+    pytest.mark.usefixtures('references'),
+    pytest.mark.parametrize('references', [['MARK1']], indirect=True)
+]
+
+
+def test_transcript_to_protein():
+    """
+    Get protein for transcript.
+    """
+    assert ncbi.transcript_to_protein('NM_018650') == 'NP_061120'
+
+
+def test_transcript_to_protein_negative():
+    """
+    Get no protein for transcript.
+    """
+    assert ncbi.transcript_to_protein('XM_005273133') is None
+
+
+def test_protein_to_transcript():
+    """
+    Get transcript for protein.
+    """
+    assert ncbi.protein_to_transcript('NP_061120') == 'NM_018650'