Added tests for spellcheck

ease/tests/test_spellcheck.py

+from unittest import TestCase
+from nose.tools import assert_equal
+from mock import patch
+from ease.util_functions import spell_correct
+
+
+class SpellCheckUnitTest(TestCase):
+    """
+    Test that spell-check works correctly.
+    """
+
+    def test_all_correct(self):
+        self._assert_spell(
+            "The quick brown dog jumped over the lazy fox.",
+            "The quick brown dog jumped over the lazy fox.",
+            0, "The quick brown dog jumped over the lazy fox."
+        )
+
+    def test_some_misspelled(self):
+        self._assert_spell(
+            "The quuick brown dog jimped over the lazy fox.",
+            "The quick brown dog jumped over the lazy fox.",
+            2, "The <bs>quuick</bs> brown dog <bs>jimped</bs> over the lazy fox.",
+        )
+
+    def test_empty_str(self):
+        self._assert_spell("", "", 0, "")
+
+    def test_unicode(self):
+        self._assert_spell(
+            "The quick brown dog jimped over the \u00FCber fox.",
+            "The quick brown dog jumped over the \u00FCber fox.",
+            2, "The quick brown dog <bs>jimped</bs> over the \u00FCber fox.",
+        )
+
+    @patch("util_functions.os.popen")
+    def test_aspell_not_found(self, popen_mock):
+
+        # Expected behavior when aspell is not installed is to return the original
+        # string with no corrections.
+        popen_mock.side_effect = OSError
+        self._assert_spell("Test striiing", "Test striiing", 0, "Test striiing")
+
+    def _assert_spell(self, input_str, expected_str, expected_num_changed, expected_markup):
+        result = spell_correct(input_str)
+        assert_equal(result, (expected_str, expected_num_changed, expected_markup))