Better handle running the tests without PIL installed.

9 files changed, 75 insertions, 20 deletions

diff --git a/conftest.py b/conftest.py
index e4371a3..535bb68 100644
--- a/conftest.py
+++ b/conftest.py
@@ -11,6 +11,8 @@ import pytest
 import scss
 from scss.compiler import compile_file
 import scss.config
+from scss.errors import SassEvaluationError
+from scss.errors import SassMissingDependency
 from scss.extension.core import CoreExtension
 from scss.extension.extra import ExtraExtension
 from scss.extension.fonts import FontsExtension
@@ -115,17 +117,27 @@ class SassItem(pytest.Item):
             search_path.append(include)
         search_path.append(scss_file.parent)
 
-        actual = compile_file(
-            scss_file,
-            output_style='expanded',
-            search_path=search_path,
-            extensions=[
-                CoreExtension,
-                ExtraExtension,
-                FontsExtension,
-                CompassExtension,
-            ],
-        )
+        try:
+            actual = compile_file(
+                scss_file,
+                output_style='expanded',
+                search_path=search_path,
+                extensions=[
+                    CoreExtension,
+                    ExtraExtension,
+                    FontsExtension,
+                    CompassExtension,
+                ],
+            )
+        except SassEvaluationError as e:
+            # Treat any missing dependencies (PIL not installed, fontforge not
+            # installed) as skips
+            # TODO this is slightly cumbersome and sorta defeats the purpose of
+            # having separate exceptions
+            if isinstance(e.exc, SassMissingDependency):
+                pytest.skip(e.format_message())
+            else:
+                raise
 
         # Normalize leading and trailing newlines
         actual = actual.strip('\n')
diff --git a/scss/errors.py b/scss/errors.py
index 75d98b6..b06793c 100644
--- a/scss/errors.py
+++ b/scss/errors.py
@@ -168,6 +168,22 @@ class SassImportError(SassBaseError):
         )
 
 
+class SassMissingDependency(SassBaseError):
+    """Error raised when an optional library (e.g., PIL or fontforge) is
+    missing.
+    """
+
+    def __init__(self, library, activity, **kwargs):
+        super(SassMissingDependency, self).__init__(**kwargs)
+
+        self.library = library
+        self.activity = activity
+
+    def format_message(self):
+        return "{0} requires {1}, which is not installed".format(
+            self.activity, self.library)
+
+
 class SassError(SassBaseError):
     """Error class that wraps another exception and attempts to bolt on some
     useful context.
diff --git a/scss/extension/compass/images.py b/scss/extension/compass/images.py
index 465246c..b2f33f1 100644
--- a/scss/extension/compass/images.py
+++ b/scss/extension/compass/images.py
@@ -13,6 +13,7 @@ from six.moves import xrange
 from . import CompassExtension
 from .helpers import add_cache_buster
 from scss import config
+from scss.errors import SassMissingDependency
 from scss.types import Color, List, Number, String, Url
 from scss.util import getmtime, make_data_url, make_filename_hash
 from scss.extension import Cache
@@ -49,7 +50,7 @@ def _image_url(path, only_path=False, cache_buster=True, dst_color=None, src_col
     """
     if inline or dst_color or spacing:
         if not Image:
-            raise Exception("Images manipulation require PIL")
+            raise SassMissingDependency('PIL', 'image manipulation')
 
     filepath = String.unquoted(path).value
     fileext = os.path.splitext(filepath)[1].lstrip('.').lower()
@@ -223,7 +224,7 @@ def image_width(image):
     relative to your project's images directory.
     """
     if not Image:
-        raise Exception("Images manipulation require PIL")
+        raise SassMissingDependency('PIL', 'image manipulation')
 
     image_size_cache = _get_cache('image_size_cache')
 
@@ -261,7 +262,7 @@ def image_height(image):
     """
     image_size_cache = _get_cache('image_size_cache')
     if not Image:
-        raise Exception("Images manipulation require PIL")
+        raise SassMissingDependency('PIL', 'image manipulation')
     filepath = String.unquoted(image).value
     path = None
     try:
diff --git a/scss/extension/compass/sprites.py b/scss/extension/compass/sprites.py
index e8208d6..28ba4fb 100644
--- a/scss/extension/compass/sprites.py
+++ b/scss/extension/compass/sprites.py
@@ -33,6 +33,7 @@ from six.moves import xrange
 from . import CompassExtension
 from .layouts import PackedSpritesLayout, HorizontalSpritesLayout, VerticalSpritesLayout, DiagonalSpritesLayout
 from scss import config
+from scss.errors import SassMissingDependency
 from scss.types import Color, List, Number, String, Boolean
 from scss.util import escape, getmtime, make_data_url, make_filename_hash
 from scss.extension import Cache
@@ -121,7 +122,7 @@ def sprite_map(g, **kwargs):
     $collapse-y  - Collapses a size for `y`.
     """
     if not Image:
-        raise Exception("Images manipulation require PIL")
+        raise SassMissingDependency('PIL', 'image manipulation')
 
     sprite_maps = _get_cache('sprite_maps')
 
diff --git a/scss/extension/extra.py b/scss/extension/extra.py
index 30cbe5f..3edc9f3 100644
--- a/scss/extension/extra.py
+++ b/scss/extension/extra.py
@@ -12,6 +12,7 @@ import six
 from six.moves import xrange
 
 from scss import config
+from scss.errors import SassMissingDependency
 from scss.extension import Extension
 from scss.namespace import Namespace
 from scss.types import Color, Number, String, List
@@ -275,7 +276,7 @@ def _image_brushed(pixdata, size, density=None, intensity=None, color=None, opac
 @ns.declare
 def background_noise(density=None, opacity=None, size=None, monochrome=False, intensity=(), color=None, background=None, inline=False):
     if not Image:
-        raise Exception("Images manipulation require PIL")
+        raise SassMissingDependency('PIL', 'image manipulation')
 
     density = [Number(v).value for v in List.from_maybe(density)]
     intensity = [Number(v).value for v in List.from_maybe(intensity)]
@@ -325,7 +326,7 @@ def background_noise(density=None, opacity=None, size=None, monochrome=False, in
 @ns.declare
 def background_brushed(density=None, intensity=None, color=None, opacity=None, size=None, monochrome=False, direction=(), spread=(), background=None, inline=False):
     if not Image:
-        raise Exception("Images manipulation require PIL")
+        raise SassMissingDependency('PIL', 'image manipulation')
 
     density = [Number(v).value for v in List.from_maybe(density)]
     intensity = [Number(v).value for v in List.from_maybe(intensity)]
@@ -378,7 +379,7 @@ def background_brushed(density=None, intensity=None, color=None, opacity=None, s
 @ns.declare
 def grid_image(left_gutter, width, right_gutter, height, columns=1, grid_color=None, baseline_color=None, background_color=None, inline=False):
     if not Image:
-        raise Exception("Images manipulation require PIL")
+        raise SassMissingDependency('PIL', 'image manipulation')
     if grid_color is None:
         grid_color = (120, 170, 250, 15)
     else:
@@ -443,7 +444,7 @@ def grid_image(left_gutter, width, right_gutter, height, columns=1, grid_color=N
 @ns.declare
 def image_color(color, width=1, height=1):
     if not Image:
-        raise Exception("Images manipulation require PIL")
+        raise SassMissingDependency('PIL', 'image manipulation')
     w = int(Number(width).value)
     h = int(Number(height).value)
     if w <= 0 or h <= 0:
diff --git a/scss/extension/fonts.py b/scss/extension/fonts.py
index 67a3b2d..b772ceb 100644
--- a/scss/extension/fonts.py
+++ b/scss/extension/fonts.py
@@ -26,6 +26,7 @@ except:
     fontforge = None
 
 from scss import config
+from scss.errors import SassMissingDependency
 from scss.extension import Extension
 from scss.namespace import Namespace
 from scss.types import Boolean, List, String, Url
@@ -129,7 +130,7 @@ def ttf2eot(ttf):
 @ns.declare
 def font_sheet(g, **kwargs):
     if not fontforge:
-        raise Exception("Fonts manipulation require fontforge")
+        raise SassMissingDependency('fontforge', 'font manipulation')
 
     font_sheets = _get_cache('font_sheets')
 
diff --git a/scss/tests/functions/compass/test_images.py b/scss/tests/functions/compass/test_images.py
index a5d0312..025a32e 100644
--- a/scss/tests/functions/compass/test_images.py
+++ b/scss/tests/functions/compass/test_images.py
@@ -20,6 +20,7 @@ import pytest
 from scss import config
 from scss.calculator import Calculator
 from scss.extension.compass import CompassExtension
+from scss.tests.util import needs_PIL
 
 
 # TODO many of these tests could also stand to test for failure cases
@@ -36,6 +37,7 @@ def test_image_url(calc):
 
 
 # inline-image
+@needs_PIL
 def test_inline_image(calc, monkeypatch):
     monkeypatch.setattr(config, 'IMAGES_ROOT', os.path.join(config.PROJECT_ROOT, 'tests/files/images'))
 
@@ -45,6 +47,7 @@ def test_inline_image(calc, monkeypatch):
 
 
 @pytest.mark.skipif(sys.platform == 'win32', reason='cur mimetype is defined on windows')
+@needs_PIL
 def test_inline_cursor(calc, monkeypatch):
     monkeypatch.setattr(config, 'IMAGES_ROOT', os.path.join(config.PROJECT_ROOT, 'tests/files/cursors'))
 
diff --git a/scss/tests/functions/test_extra.py b/scss/tests/functions/test_extra.py
index 8940e94..d9f97cb 100644
--- a/scss/tests/functions/test_extra.py
+++ b/scss/tests/functions/test_extra.py
@@ -8,25 +8,30 @@ from __future__ import absolute_import
 from __future__ import unicode_literals
 
 import scss.extension.extra as libextra
+from scss.tests.util import needs_PIL
 from scss.types import Boolean, Color, Number
 
 
 # TODO: currently these all just call the functions and make sure they pass.
 # would be nice to check the output, though that's a little tedious.
 
+@needs_PIL
 def test_background_noise():
     libextra.background_noise(Number(0.5), Number(0.5), Number(100), Boolean(True), color=Color.from_name('green'))
 
 
+@needs_PIL
 def test_background_brushed():
     libextra.background_brushed(Number(0.5), Number(0.5), Color.from_name('red'), Number(0.5))
 
 
+@needs_PIL
 def test_grid_image():
     # TODO this should accept sass values only  :|
     libextra.grid_image(5, 100, 5, 100)
 
 
+@needs_PIL
 def test_image_color():
     libextra.image_color(Color.from_rgb(1, 1, 0))
     assert True
diff --git a/scss/tests/util.py b/scss/tests/util.py
new file mode 100644
index 0000000..8b36d7d
--- /dev/null
+++ b/scss/tests/util.py
@@ -0,0 +1,15 @@
+"""Test utilities."""
+from __future__ import absolute_import
+
+import pytest
+
+try:
+    import PIL
+except ImportError:
+    try:
+        import Image as PIL
+    except ImportError:
+        PIL = None
+
+
+needs_PIL = pytest.mark.skipif(PIL is None, reason='image tests require PIL')