Merge branch 'master' into urandom-engine

* master: (58 commits)
  Moar backtick.
  Add to changelog.
  move some dashes around :)
  experiment to disable duplicate cc test runs on osx and speed up travis
  Remove register_cipher_adapter from the interface and the documentation.
  expand tox backend example
  On OS X at build time compile the CC bindings
  remove an extraneous linefeed
  reformat bindings and remove GCM for the moment
  add cipher bindings for CommonCrypto
  doc updates
  hmac support for commoncrypto
  added versionadded
  changelog to note addition of commoncrypto backend with hash support
  fix docs
  doc updates
  update docs for name attribute
  fix copy mistake in docs
  increase indent and note the value of the attribute in the docs
  move HashMethods to top level
  ...

3 files changed, 76 insertions, 5 deletions

diff --git a/tests/conftest.py b/tests/conftest.py
index 1d9f96ed..a9acb54a 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -5,12 +5,15 @@ from cryptography.hazmat.backends.interfaces import (
     HMACBackend, CipherBackend, HashBackend
 )
 
-from .utils import check_for_iface, check_backend_support
+from .utils import check_for_iface, check_backend_support, select_backends
 
 
-@pytest.fixture(params=_ALL_BACKENDS)
-def backend(request):
-    return request.param
+def pytest_generate_tests(metafunc):
+    names = metafunc.config.getoption("--backend")
+    selected_backends = select_backends(names, _ALL_BACKENDS)
+
+    if "backend" in metafunc.fixturenames:
+        metafunc.parametrize("backend", selected_backends)
 
 
 @pytest.mark.trylast
@@ -19,3 +22,10 @@ def pytest_runtest_setup(item):
     check_for_iface("cipher", CipherBackend, item)
     check_for_iface("hash", HashBackend, item)
     check_backend_support(item)
+
+
+def pytest_addoption(parser):
+    parser.addoption(
+        "--backend", action="store", metavar="NAME",
+        help="Only run tests matching the backend NAME."
+    )
diff --git a/tests/test_utils.py b/tests/test_utils.py
index e3e53d63..f852f3ab 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -21,7 +21,7 @@ import pytest
 from .utils import (
     load_nist_vectors, load_vectors_from_file, load_cryptrec_vectors,
     load_openssl_vectors, load_hash_vectors, check_for_iface,
-    check_backend_support
+    check_backend_support, select_backends
 )
 
 
@@ -29,6 +29,48 @@ class FakeInterface(object):
     pass
 
 
+def test_select_one_backend():
+    b1 = pretend.stub(name="b1")
+    b2 = pretend.stub(name="b2")
+    b3 = pretend.stub(name="b3")
+    backends = [b1, b2, b3]
+    name = "b2"
+    selected_backends = select_backends(name, backends)
+    assert len(selected_backends) == 1
+    assert selected_backends[0] == b2
+
+
+def test_select_no_backend():
+    b1 = pretend.stub(name="b1")
+    b2 = pretend.stub(name="b2")
+    b3 = pretend.stub(name="b3")
+    backends = [b1, b2, b3]
+    name = "back!"
+    with pytest.raises(ValueError):
+        select_backends(name, backends)
+
+
+def test_select_backends_none():
+    b1 = pretend.stub(name="b1")
+    b2 = pretend.stub(name="b2")
+    b3 = pretend.stub(name="b3")
+    backends = [b1, b2, b3]
+    name = None
+    selected_backends = select_backends(name, backends)
+    assert len(selected_backends) == 3
+
+
+def test_select_two_backends():
+    b1 = pretend.stub(name="b1")
+    b2 = pretend.stub(name="b2")
+    b3 = pretend.stub(name="b3")
+    backends = [b1, b2, b3]
+    name = "b2 ,b1 "
+    selected_backends = select_backends(name, backends)
+    assert len(selected_backends) == 2
+    assert selected_backends == [b1, b2]
+
+
 def test_check_for_iface():
     item = pretend.stub(keywords=["fake_name"], funcargs={"backend": True})
     with pytest.raises(pytest.skip.Exception) as exc_info:
diff --git a/tests/utils.py b/tests/utils.py
index 693a0c8f..a2432256 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -16,6 +16,25 @@ import os
 import pytest
 
 
+def select_backends(names, backend_list):
+    if names is None:
+        return backend_list
+    split_names = [x.strip() for x in names.split(',')]
+    # this must be duplicated and then removed to preserve the metadata
+    # pytest associates. Appending backends to a new list doesn't seem to work
+    selected_backends = []
+    for backend in backend_list:
+        if backend.name in split_names:
+            selected_backends.append(backend)
+
+    if len(selected_backends) > 0:
+        return selected_backends
+    else:
+        raise ValueError(
+            "No backend selected. Tried to select: {0}".format(split_names)
+        )
+
+
 def check_for_iface(name, iface, item):
     if name in item.keywords and "backend" in item.funcargs:
         if not isinstance(item.funcargs["backend"], iface):