tests: Smoke test __str__() and __repr__()

It is extremely annoying to have an exception obscured by an exception
in repr or str.  The concrete output of str and repr, however, is bound
to change and therefore, it needs not be tested.

tests/test_md.py

@@ -67,6 +67,10 @@ def digest_size(self):
     def block_size(self):
         raise NotImplementedError
 
+    @pytest.mark.parametrize("repr_", (repr, str), ids=lambda f: f.__name__)
+    def test_repr(self, repr_, algorithm):
+        assert isinstance(repr_(algorithm), str)
+
     def test_digest_size_accessor(self, algorithm, digest_size):
         assert algorithm.digest_size == digest_size
 

tests/test_mpi.py

@@ -14,6 +14,11 @@ def test_from_int(value):
     assert mpi == mpi
 
 
+@pytest.mark.parametrize("repr_", (repr, str), ids=lambda f: f.__name__)
+def test_repr(repr_):
+    assert isinstance(repr_(MPI(69)), str)
+
+
 def test_is_integral():
     assert isinstance(MPI(42), numbers.Integral)
 

tests/test_tls.py

@@ -46,6 +46,10 @@ def psk_store(self):
     def proxy(self, psk_store):
         return PSKStoreProxy(psk_store)
 
+    @pytest.mark.parametrize("repr_", (repr, str), ids=lambda f: f.__name__)
+    def test_repr(self, repr_, psk_store):
+        assert isinstance(repr_(psk_store), str)
+
     def test_unwrap(self, proxy, psk_store):
         assert proxy.unwrap() == psk_store
 
@@ -123,6 +127,10 @@ def length(self):
     def header(self, record_type, version, length):
         return TLSRecordHeader(record_type, version, length)
 
+    @pytest.mark.parametrize("repr_", (repr, str), ids=lambda f: f.__name__)
+    def test_repr(self, repr_, record_type):
+        assert isinstance(repr_(record_type), str)
+
     def test_accessors(self, header, record_type, version, length):
         assert len(header) == 5
         assert header.record_type is record_type
@@ -200,6 +208,10 @@ class TestTrustStore(Chain):
     def store(self):
         return TrustStore.system()
 
+    @pytest.mark.parametrize("repr_", (repr, str), ids=lambda f: f.__name__)
+    def test_repr(self, repr_, store):
+        assert isinstance(repr_(store), str)
+
     def test_eq(self, store):
         other = TrustStore(store)
         assert store is not other
@@ -252,6 +264,10 @@ def conf(self):
     def version(self):
         raise NotImplementedError
 
+    @pytest.mark.parametrize("repr_", (repr, str), ids=lambda f: f.__name__)
+    def test_repr(self, repr_, conf):
+        assert isinstance(repr_(conf), str)
+
     @pytest.mark.parametrize("validate", [True, False])
     def test_set_validate_certificates(self, conf, validate):
         conf_ = conf.update(validate_certificates=validate)
@@ -383,6 +399,14 @@ def test_get_channel_binding(self, context):
     # def test_negotiated_tls_version(self, context):
     #     assert context._negotiated_tls_version() is TLSVersion.SSLv3
 
+    @pytest.fixture
+    def tls_wrapped_buffer(self, context):
+        return TLSWrappedBuffer(context)
+
+    @pytest.mark.parametrize("repr_", (repr, str), ids=lambda f: f.__name__)
+    def test_repr_tls_wrapped_buffer(self, repr_, tls_wrapped_buffer):
+        assert isinstance(repr_(tls_wrapped_buffer), str)
+
 
 class TestClientContext(TestBaseContext):
     @pytest.fixture(params=[None, "hostname", "localhost"])

tests/test_x509.py

@@ -49,7 +49,9 @@ def subject_key():
 
 
 class _X509Base:
-    # Derive and provide `x509`.
+    @pytest.fixture
+    def x509(self):
+        raise NotImplementedError
 
     @pytest.fixture
     def der(self, x509):
@@ -61,6 +63,10 @@ def pem(self, x509):
 
 
 class _CommonTests(_X509Base):
+    @pytest.mark.parametrize("repr_", (repr, str), ids=lambda f: f.__name__)
+    def test_repr(self, repr_, x509):
+        assert isinstance(repr_(x509), str)
+
     def test_from_buffer(self, x509, der):
         assert type(x509).from_buffer(der) == x509