add tests

tests/test_structure.py

@@ -0,0 +1,20 @@
+"""Test of structure module.
+
+"""
+import unittest
+import fvr.structure
+
+class TestStructureBeam(unittest.TestCase):
+  def setUp(self):
+    self.obj = fvr.structure.beam(1, 2, 3, 4, 5)
+  def test_volume(self):
+    self.assertEqual(self.obj.V, 12, 'incorrect volume after creation')
+  def test_volume_a(self):
+    self.obj.A = 6
+    self.assertEqual(self.obj.V, 24, 'incorrect volume after changing A')
+  def test_volume_l(self):
+    self.obj.L = 7
+    self.assertEqual(self.obj.V, 21, 'incorrect volume after changing L')
+
+if __name__ == '__main__':
+  unittest.main()