Add test for correct derived algorithm

Author: fulder

httpsig/tests/test_verify.py

@@ -255,4 +255,18 @@ def test_algorithm_mismatch(self):
 
         hv = HeaderVerifier(
             headers=signed, secret=self.verify_secret, sign_header=self.sign_header, algorithm="rsa-sha256", sign_algorithm=self.sign_algorithm)
-        self.assertFalse(hv.verify())
+        self.assertFalse(hv.verify())
+
+    def test_correct_derviced_algorithm(self):
+        unsigned = {
+            'Date': self.header_date
+        }
+
+        hs = HeaderSigner(
+            key_id="Test", secret=self.sign_secret, algorithm=self.algorithm,
+            sign_header=self.sign_header, sign_algorithm=self.sign_algorithm)
+        signed = hs.sign(unsigned)
+
+        hv = HeaderVerifier(
+            headers=signed, secret=self.verify_secret, sign_header=self.sign_header, algorithm="hs2019", sign_algorithm=self.sign_algorithm)
+        self.assertTrue(hv.verify())