test backend.view with mock

.travis.yml

@@ -11,6 +11,6 @@ before_install:
   - sudo apt-get install -y graphviz
 install:
   - pip install -e .
-  - pip install "pytest>=3" pytest-cov coveralls
+  - pip install mock "pytest>=3" pytest-cov coveralls
 script: pytest
 after_success: if [[ $TRAVIS_PYTHON_VERSION == 3.6* ]]; then coveralls; fi

CHANGES

@@ -5,7 +5,7 @@ Changelog
 Version 0.7.1 (in development)
 ------------------------------
 
-
+Fix graphivz.view exception on unsupported platform.
 
 
 Version 0.7

graphviz/backend.py

@@ -155,7 +155,7 @@ def view(filepath):
     """
     try:
         view_func = getattr(view, PLATFORM)
-    except KeyError:
+    except AttributeError:
         raise RuntimeError('platform %r not supported' % PLATFORM)
     view_func(filepath)
 

requirements.txt

@@ -1,5 +1,6 @@
 # exact dependency versions used in development
 # dependencies for testing and building
+mock
 pytest>=3
 pytest-cov
 coverage

tests/test_backend.py

@@ -2,15 +2,10 @@
 
 import subprocess
 
+import mock
 import pytest
 
-from graphviz.backend import render, pipe
-
-
-def test_render_filepath_missing():
-    with pytest.raises(subprocess.CalledProcessError) as e:
-        render('dot', 'pdf', 'doesnotexist')
-    assert e.value.returncode == 2
+from graphviz.backend import render, pipe, view
 
 
 def test_render_engine_unknown():
@@ -25,7 +20,13 @@ def test_render_format_unknown():
     e.match(r'format')
 
 
-def test_pipe_invalid_dot():
+def test_render_missingfile():
+    with pytest.raises(subprocess.CalledProcessError) as e:
+        render('dot', 'pdf', 'doesnotexist')
+    assert e.value.returncode == 2
+
+
+def test_pipe_invalid_data():
     with pytest.raises(subprocess.CalledProcessError) as e:
         pipe('dot', 'svg', b'spam', quiet=True)
     assert e.value.returncode == 1
@@ -34,3 +35,31 @@ def test_pipe_invalid_dot():
 def test_pipe(svg_pattern):
     src = pipe('dot', 'svg', b'graph { spam }').decode('ascii')
     assert svg_pattern.match(src)
+
+
+@mock.patch('graphviz.backend.PLATFORM', 'spam')
+def test_view_unsupported():
+    with pytest.raises(RuntimeError) as e:
+        view('spam')
+    e.match(r'platform')
+
+
+@mock.patch('graphviz.backend.PLATFORM', 'darwin')
+@mock.patch('subprocess.Popen')
+def test_view_darwin(Popen):
+    view('spam')
+    Popen.assert_called_once_with(['open', 'spam'])
+
+
+@mock.patch('graphviz.backend.PLATFORM', 'linux')
+@mock.patch('subprocess.Popen')
+def test_view_linux(Popen):
+    view('spam')
+    Popen.assert_called_once_with(['xdg-open', 'spam'])
+
+
+@mock.patch('graphviz.backend.PLATFORM', 'windows')
+@mock.patch('os.startfile')
+def test_view_windows(startfile):
+    view('spam')
+    startfile.assert_called_once_with('spam')