new tests to improve coverage

example_module.scad

@@ -0,0 +1,4 @@
+module example() {offset(r=10){
+    circle(r=10);
+};}
+example();

tests/test_base.py

@@ -200,6 +200,20 @@ def test_offset(self):
         with self.assertRaises(TypeError):
             o.offset([10, 10, 10])
 
+    def test_hull(self):
+        c = Cube(10)
+        s = Sphere(3)
+        s = s.translate([8, 0, 0])
+        h = (c + s).hull()
+        self.assertTrue('hull' in h.dumps())
+
+    def test_minkowski(self):
+        c = Cube(10)
+        s = Sphere(3)
+        s = s.translate([8, 0, 0]) 
+        h = (c + s).minkowski()
+        self.assertTrue('minkowski' in h.dumps())
+
     def test_linear_extrude(self):
         o = Circle(10)
         o1 = o.linear_extrude(height=1.6)
@@ -212,6 +226,11 @@ def test_rotate_extrude(self):
         self.assertTrue(isinstance(o1, Rotate_Extrude))
         self.assertEqual(o1.children, [o])
 
+    def test_scad_write(self):
+        sc = Scad(os.path.join(os.path.dirname(os.path.abspath(__file__)),'..','example','example.scad')) 
+        self.assertTrue('example' in sc.dumps())
+        sc.write('example_module.scad')
+
     def test_scad(self):
         o = Sphere(3)
         sc = Scad(os.path.join(os.path.dirname(os.path.abspath(__file__)),'..','example','example.scad'))