Convert test_rand to use pytest-style tests (#563)

Fix up the assert helpers, subclass form `object` rather than test case,
and use parametrization where appropriate.

One helper method on the original `TestCase` was the ability to create
temporary directories that were cleaned up at the end of the test --
now we use a pytest fixture instead: http://doc.pytest.org/en/latest/tmpdir.html

Addresses #340.

1 files changed, 14 insertions, 0 deletions

diff --git a/tests/conftest.py b/tests/conftest.py
index 5a9954f..366624e 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,6 +1,10 @@
 # Copyright (c) The pyOpenSSL developers
 # See LICENSE for details.
 
+from tempfile import mktemp
+
+import pytest
+
 
 def pytest_report_header(config):
     import OpenSSL.SSL
@@ -10,3 +14,13 @@ def pytest_report_header(config):
         openssl=OpenSSL.SSL.SSLeay_version(OpenSSL.SSL.SSLEAY_VERSION),
         cryptography=cryptography.__version__
     )
+
+
+@pytest.fixture
+def tmpfile(tmpdir):
+    """
+    Return UTF-8-encoded bytes of a path to a tmp file.
+
+    The file will be cleaned up after the test run.
+    """
+    return mktemp(dir=tmpdir.dirname).encode("utf-8")