refactor view tests with parametrized fixture

tests/conftest.py

@@ -11,26 +11,9 @@ def svg_pattern():
     return re.compile(r'(?s)^<\?xml .+</svg>\s*$')
 
 
-@pytest.fixture
-def unknown_platform(name='spam'):
-    with mock.patch('graphviz.backend.PLATFORM', name):
-        yield name
-
-
-@pytest.fixture
-def darwin(name='darwin'):
-    with mock.patch('graphviz.backend.PLATFORM', name):
-        yield name
-
-
-@pytest.fixture
-def unixoid(name='linux'):
-    with mock.patch('graphviz.backend.PLATFORM', name):
-        yield name
-
-
-@pytest.fixture
-def windows(name='windows'):
+@pytest.fixture(params=['', 'darwin', 'freebsd', 'linux', 'windows'])
+def platform(request):
+    name = request.param
     with mock.patch('graphviz.backend.PLATFORM', name):
         yield name
 

tests/test_backend.py

@@ -36,22 +36,18 @@ def test_pipe(svg_pattern):
     assert svg_pattern.match(src)
 
 
-def test_view_unknown(unknown_platform):
-    with pytest.raises(RuntimeError) as e:
+def test_view(platform, Popen, startfile):
+    if not platform:
+        with pytest.raises(RuntimeError) as e:
+            view('spam')
+        e.match(r'platform')
+    else:
         view('spam')
-    e.match(r'platform')
-
-
-def test_view_darwin(darwin, Popen):
-    view('spam')
-    Popen.assert_called_once_with(['open', 'spam'])
-
-
-def test_view_unixoid(unixoid, Popen):
-    view('spam')
-    Popen.assert_called_once_with(['xdg-open', 'spam'])
-
-
-def test_view_windows(windows, startfile):
-    view('spam')
-    startfile.assert_called_once_with('spam')
+        if platform == 'darwin':
+            Popen.assert_called_once_with(['open', 'spam'])
+        elif platform in ('linux', 'freebsd'):
+            Popen.assert_called_once_with(['xdg-open', 'spam'])
+        elif platform == 'windows':
+            startfile.assert_called_once_with('spam')
+        else:
+            raise RuntimeError

tests/test_files.py

@@ -63,25 +63,21 @@ def test_render_noent(file_noent):
     e.match(r'failed to execute')
 
 
-def test_view_unknown(unknown_platform, file):
-    with pytest.raises(RuntimeError) as e:
+def test_view_unknown(platform, Popen, startfile, file):
+    if not platform:
+        with pytest.raises(RuntimeError) as e:
+            file._view('name', 'png')
+        e.match(r'support')
+    else:
         file._view('name', 'png')
-    e.match(r'support')
-
-
-def test_view_darwin(darwin, Popen, file):
-    file._view('name', 'png')
-    Popen.assert_called_once_with(['open', 'name'])
-
-
-def test_view_unixoid(unixoid, Popen, file):
-    file._view('name', 'png')
-    Popen.assert_called_once_with(['xdg-open', 'name'])
-
-
-def test_view_windows(windows, startfile, file):
-    file._view('name', 'png')
-    startfile.assert_called_once_with('name')
+        if platform == 'darwin':
+            Popen.assert_called_once_with(['open', 'name'])
+        elif platform in ('freebsd', 'linux'):
+            Popen.assert_called_once_with(['xdg-open', 'name'])
+        elif platform == 'windows':
+            startfile.assert_called_once_with('name')
+        else:
+            raise RuntimeError
 
 
 def test_source():