Fix pytest 5.0.0 compatibility

pytest.raises() returns exception info not the exception itself. They
changed implementation of exception info, so now .value property must be
used to get the exception instance and have proper output from str()
method.

pytest-dev/pytest#5412

Signed-off-by: Martin Bašti <mbasti@redhat.com>

tests/test_util.py

@@ -29,15 +29,15 @@ def test_parse_address(test_input, expected):
 
 
 def test_parse_address_invalid():
-    with pytest.raises(RuntimeError) as err:
+    with pytest.raises(RuntimeError) as exc_info:
         util.parse_address('127.0.0.1:test')
-    assert "'test' is not a valid port number." in str(err)
+    assert "'test' is not a valid port number." in str(exc_info.value)
 
 
 def test_parse_fd_invalid():
-    with pytest.raises(RuntimeError) as err:
+    with pytest.raises(RuntimeError) as exc_info:
         util.parse_address('fd://asd')
-    assert "'asd' is not a valid file descriptor." in str(err)
+    assert "'asd' is not a valid file descriptor." in str(exc_info.value)
 
 
 def test_http_date():
@@ -63,24 +63,24 @@ def test_warn(capsys):
 def test_import_app():
     assert util.import_app('support:app')
 
-    with pytest.raises(ImportError) as err:
+    with pytest.raises(ImportError) as exc_info:
         util.import_app('a:app')
-    assert 'No module' in str(err)
+    assert 'No module' in str(exc_info.value)
 
-    with pytest.raises(AppImportError) as err:
+    with pytest.raises(AppImportError) as exc_info:
         util.import_app('support:wrong_app')
     msg = "Failed to find application object 'wrong_app' in 'support'"
-    assert msg in str(err)
+    assert msg in str(exc_info.value)
 
 
 def test_to_bytestring():
     assert util.to_bytestring('test_str', 'ascii') == b'test_str'
     assert util.to_bytestring('test_str®') == b'test_str\xc2\xae'
     assert util.to_bytestring(b'byte_test_str') == b'byte_test_str'
-    with pytest.raises(TypeError) as err:
+    with pytest.raises(TypeError) as exc_info:
         util.to_bytestring(100)
     msg = '100 is not a string'
-    assert msg in str(err)
+    assert msg in str(exc_info.value)
 
 
 @pytest.mark.parametrize('test_input, expected', [