2 files changed, 21 insertions, 4 deletions
diff --git a/tests/hazmat/backends/test_multibackend.py b/tests/hazmat/backends/test_multibackend.py
index 4d17cdb0..2a533750 100644
--- a/tests/hazmat/backends/test_multibackend.py
+++ b/tests/hazmat/backends/test_multibackend.py
@@ -152,10 +152,7 @@ class DummyEllipticCurveBackend(object):
     ):
         return (
             isinstance(signature_algorithm, ec.ECDSA) and
-            any(
-                isinstance(curve, curve_type)
-                for curve_type in self._curves
-            )
+            self.elliptic_curve_supported(curve)
         )
 
     def generate_elliptic_curve_private_key(self, curve):
@@ -170,6 +167,12 @@ class DummyEllipticCurveBackend(object):
         if not self.elliptic_curve_supported(numbers.curve):
             raise UnsupportedAlgorithm(_Reasons.UNSUPPORTED_ELLIPTIC_CURVE)
 
+    def elliptic_curve_exchange_algorithm_supported(self, algorithm, curve):
+        return (
+            isinstance(algorithm, ec.ECDH) and
+            self.elliptic_curve_supported(curve)
+        )
+
 
 @utils.register_interface(PEMSerializationBackend)
 class DummyPEMSerializationBackend(object):
@@ -462,6 +465,14 @@ class TestMultiBackend(object):
                 )
             )
 
+        assert backend.elliptic_curve_exchange_algorithm_supported(
+            ec.ECDH(), ec.SECT283K1()
+        )
+        backend2 = MultiBackend([DummyEllipticCurveBackend([])])
+        assert not backend2.elliptic_curve_exchange_algorithm_supported(
+            ec.ECDH(), ec.SECT163K1()
+        )
+
     def test_pem_serialization_backend(self):
         backend = MultiBackend([DummyPEMSerializationBackend()])
 
diff --git a/tests/hazmat/backends/test_openssl.py b/tests/hazmat/backends/test_openssl.py
index 8fd0d711..85331595 100644
--- a/tests/hazmat/backends/test_openssl.py
+++ b/tests/hazmat/backends/test_openssl.py
@@ -551,6 +551,12 @@ class TestOpenSSLEllipticCurve(object):
         with raises_unsupported_algorithm(_Reasons.UNSUPPORTED_ELLIPTIC_CURVE):
             _sn_to_elliptic_curve(backend, b"fake")
 
+    def test_elliptic_curve_exchange_algorithm_supported(self, monkeypatch):
+        monkeypatch.setattr(backend, "_lib", DummyLibrary())
+        assert not backend.elliptic_curve_exchange_algorithm_supported(
+            ec.ECDH(), ec.SECP256R1()
+        )
+
 
 @pytest.mark.requires_backend_interface(interface=RSABackend)
 class TestRSAPEMSerialization(object):