add test file for data module

tests/test_data.py

@@ -0,0 +1,31 @@
+"""Test of data module.
+
+:Date: 2019-06-12
+
+.. module:: test_data
+  :platform: *nix, Windows
+  :synopsis: Test of data module.
+
+.. moduleauthor:: Daniel Weschke <daniel.weschke@directbox.de>
+"""
+import unittest
+
+import os
+import sys
+sys.path.insert(0, os.path.abspath('../src'))
+from data import data_read
+
+
+class TestFit(unittest.TestCase):
+
+  def test_read(self):
+    """test read function"""
+    file_name = "test_fit.dat"
+    x, y = data_read(file_name, 3, 2)
+
+    self.assertEqual(len(x), 1027)
+    self.assertEqual(len(y), 1027)
+
+
+if __name__ == '__main__':
+  unittest.main()