Using css built-in functions vs. css & scss functions vs. non-existent functions

2 files changed, 36 insertions, 24 deletions

diff --git a/scss/expression.py b/scss/expression.py
index 7dc1f71..fa2157f 100644
--- a/scss/expression.py
+++ b/scss/expression.py
@@ -144,14 +144,7 @@ class Calculator(object):
             else:
                 ast_cache[expr] = ast
 
-        try:
-            return ast.evaluate(self, divide=divide)
-        except Exception:
-            # TODO hoist me up since the rule is gone
-            #log.exception("Exception raised: %s in `%s' (%s)", e, expr, rule.file_and_line)
-            if config.DEBUG:
-                raise
-            return None
+        return ast.evaluate(self, divide=divide)
 
     def parse_expression(self, expr, target='goal'):
         ast_cache = self.get_ast_cache(target)
@@ -287,36 +280,44 @@ class CallOp(Expression):
                 kwargs[var.lstrip('$').replace('-', '_')] = value
 
         # TODO merge this with the library
+        funct = None
         try:
-            func = calculator.namespace.function(func_name, argspec_len)
+            funct = calculator.namespace.function(func_name, argspec_len)
             # @functions take a ns as first arg.  TODO: Python functions possibly
             # should too
-            if getattr(func, '__name__', None) == '__call':
-                func = partial(func, calculator.namespace)
+            if getattr(funct, '__name__', None) == '__call':
+                funct = partial(funct, calculator.namespace)
         except KeyError:
             try:
                 if kwargs:
                     raise KeyError
                 # Fallback to single parameter:
-                func = calculator.namespace.function(func_name, 1)
+                funct = calculator.namespace.function(func_name, 1)
                 args = [args]
             except KeyError:
                 if not is_builtin_css_function(func_name):
                     log.error("Function not found: %s:%s", func_name, argspec_len, extra={'stack': True})
+                    raise
+        if funct:
+            try:
+                return funct(*args, **kwargs)
+            except Exception:
+                # TODO hoist me up since the rule is gone
+                #log.exception("Exception raised: %s in `%s' (%s)", e, expr, rule.file_and_line)
+                if not is_builtin_css_function(func_name):
+                    raise
 
-                rendered_args = []
-                for var, value in evald_argpairs:
-                    rendered_value = value.render()
-                    if var is None:
-                        rendered_args.append(rendered_value)
-                    else:
-                        rendered_args.append("%s: %s" % (var, rendered_value))
-
-                return String(
-                    u"%s(%s)" % (func_name, u", ".join(rendered_args)),
-                    quotes=None)
+        rendered_args = []
+        for var, value in evald_argpairs:
+            rendered_value = value.render()
+            if var is None:
+                rendered_args.append(rendered_value)
+            else:
+                rendered_args.append("%s: %s" % (var, rendered_value))
 
-        return func(*args, **kwargs)
+        return String(
+            u"%s(%s)" % (func_name, u", ".join(rendered_args)),
+            quotes=None)
 
 
 class Literal(Expression):
diff --git a/scss/tests/test_expression.py b/scss/tests/test_expression.py
index 7acbff8..a10f21b 100644
--- a/scss/tests/test_expression.py
+++ b/scss/tests/test_expression.py
@@ -163,4 +163,15 @@ def test_parse(calc):
     ])
 
 
+def test_functions(calc):
+    ns = Namespace(functions=CORE_LIBRARY)
+    calc = Calculator(ns).calculate
+
+    assert calc('grayscale(red)') == Color((127.5, 127.5, 127.5, 1))
+    assert calc('grayscale(1)') == String('grayscale(1)', quotes=None)  # Misusing css built-in functions (with scss counterpart)
+    assert calc('skew(1)') == String('skew(1)', quotes=None)  # Missing css-only built-in functions
+    with pytest.raises(TypeError):
+        calc('unitless("X")')  # Misusing non-css built-in scss funtions
+
+
 # TODO write more!  i'm lazy.