test coverage for CurveEdTw() __str__

Author: tomato42

src/ecdsa/ellipticcurve.py

@@ -225,11 +225,17 @@ def cofactor(self):
         return self.__h
 
     def __str__(self):
-        return "CurveEdTw(p={0}, a={1}, d={2}, h={3})".format(
+        if self.__h is not None:
+            return "CurveEdTw(p={0}, a={1}, d={2}, h={3})".format(
+                self.__p,
+                self.__a,
+                self.__d,
+                self.__h,
+            )
+        return "CurveEdTw(p={0}, a={1}, d={2})".format(
             self.__p,
             self.__a,
             self.__d,
-            self.__h,
         )
 
 

src/ecdsa/test_ellipticcurve.py

@@ -14,7 +14,7 @@
 except ImportError:  # pragma: no cover
     HC_PRESENT = False
 from .numbertheory import inverse_mod
-from .ellipticcurve import CurveFp, INFINITY, Point
+from .ellipticcurve import CurveFp, INFINITY, Point, CurveEdTw
 
 
 HYP_SETTINGS = {}
@@ -105,6 +105,19 @@ def test___str___with_cofactor(self):
         self.assertEqual(str(c), "CurveFp(p=23, a=1, b=1, h=4)")
 
 
+class TestCurveEdTw(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.c_23 = CurveEdTw(23, 1, 1)
+
+    def test___str__(self):
+        self.assertEqual(str(self.c_23), "CurveEdTw(p=23, a=1, d=1)")
+
+    def test___str___with_cofactor(self):
+        c = CurveEdTw(23, 1, 1, 4)
+        self.assertEqual(str(c), "CurveEdTw(p=23, a=1, d=1, h=4)")
+
+
 class TestPoint(unittest.TestCase):
     @classmethod
     def setUpClass(cls):