Add unit tests for cells.py.

tests/unit/test_cells.py

+# -*- coding: utf-8 -*-
+from __future__ import absolute_import, division, unicode_literals
+
+import unittest
+
+from activetable.cells import NumericCell, StringCell
+
+class CellTest(unittest.TestCase):
+
+    def test_numeric_cell(self):
+        cell = NumericCell(answer=42, tolerance=1.0)
+        self.assertTrue(cell.check_response('42'))
+        self.assertTrue(cell.check_response('42.4'))
+        self.assertTrue(cell.check_response('41.6'))
+        self.assertFalse(cell.check_response('41.5'))
+        self.assertFalse(cell.check_response('43'))
+        self.assertFalse(cell.check_response('Hurz!'))
+        cell.set_tolerance(10.0)
+        self.assertTrue(cell.check_response('42'))
+        self.assertTrue(cell.check_response('46'))
+        self.assertFalse(cell.check_response('37'))
+
+    def test_significant_digits(self):
+        cell = NumericCell(
+            answer=6.238, tolerance=10.0, min_significant_digits=3, max_significant_digits=4
+        )
+        self.assertTrue(cell.check_response('6.24'))
+        self.assertTrue(cell.check_response('6.238'))
+        self.assertFalse(cell.check_response('6.2'))
+        self.assertFalse(cell.check_response('6.2382'))
+
+    def test_string_cell(self):
+        cell = StringCell('OpenCraft')
+        self.assertTrue(cell.check_response('OpenCraft'))
+        self.assertFalse(cell.check_response('giraffe'))