add unit tests for text_helpers

Addresses #4

tests.py

@@ -0,0 +1,64 @@
+import unittest
+
+import text_helpers
+
+class TestTextHelpersMethods(unittest.TestCase):
+    def test_distance(self):
+        test_cases = [
+            ("test_string", "test string", 1),
+            ("test_string", "teststring", 1),
+            ("test_strings", "teststring", 2),
+            ("test_string", "test_string", 0)
+        ]
+        for t in test_cases:
+            res = text_helpers.minimum_edit_distance(t[0], t[1])
+            self.assertEqual(res, t[-1])
+
+    def test_in_range(self):
+        test_cases = [
+            (15, (0, 10), False),
+            (15, (0, 15), False),
+            (15, (0, 16), True),
+            (-15, (-20, 10), True),
+            (-22, (-20, 10), False)
+        ]
+        for t in test_cases:
+            res = text_helpers.is_val_in_range(t[0], t[1])
+            self.assertEqual(res, t[-1])
+
+    def test_distance_replace(self):
+        test_cases = [
+            ("test_string", "test string", 1, "test_string"),
+            ("test_string", "teststring", 1, "test_string"),
+            ("test_strings", "teststring", 1, "teststring"),
+            ("test_string", "test_string", 1, "test_string"),
+            ("test_string", "node_string", 1, "node_string"),
+            ("test_string", "node_string", 4, "test_string")
+        ]
+        for t in test_cases:
+            res = text_helpers.check_distance(t[1], t[0], t[2])
+            self.assertEqual(res, t[-1])
+
+
+    def test_simple_replace(self):
+
+        REPLACE_RULES = {
+            "1,-1": ["i", "[", "]", "l", "7", "?", "t"],
+            "1,0": ["i", "[", "]", "l", "7", "?", "t"],
+            "q,": ["qg","qq","gg","gq"]
+        }
+        test_cases = [
+            ("testi", "1est1"),
+            ("test?", "1est1"),
+            ("?test", "1tes1"),
+            ("]tesn", "1tesn"),
+            ("qg", "q"),
+            ("qgqg", "q"),
+            ("qgqgqg", "qq")
+        ]
+        for t in test_cases:
+            res = text_helpers.check_replace(t[0], REPLACE_RULES)
+            self.assertEqual(res, t[-1])
+
+if __name__ == '__main__':
+    unittest.main()