Start on tests for Compass helpers.

Fixed some bugs while I was at it.

- Boolean conversion was totally wrong; Sass uses Ruby rules.
- blank() was wrong.
- compact() was needlessly complicated.

3 files changed, 73 insertions, 43 deletions

diff --git a/scss/functions/compass/helpers.py b/scss/functions/compass/helpers.py
index 172bd57..7dc08a4 100644
--- a/scss/functions/compass/helpers.py
+++ b/scss/functions/compass/helpers.py
@@ -17,7 +17,7 @@ import time
 from scss import config
 from scss.cssdefs import _undefined_re
 from scss.functions.library import FunctionLibrary
-from scss.types import BooleanValue, ListValue, NumberValue, StringValue
+from scss.types import BooleanValue, ListValue, NumberValue, QuotedStringValue, StringValue
 from scss.util import escape, to_str
 
 log = logging.getLogger(__name__)
@@ -47,55 +47,33 @@ def add_cache_buster(url, mtime):
 def blank(*objs):
     """Returns true when the object is false, an empty string, or an empty list"""
     for o in objs:
-        if bool(o):
+        if isinstance(o, BooleanValue):
+            is_blank = not o
+        elif isinstance(o, QuotedStringValue):
+            is_blank = not len(o.value.strip())
+        elif isinstance(o, ListValue):
+            is_blank = all(blank(el) for el in o)
+        else:
+            is_blank = False
+
+        if not is_blank:
             return BooleanValue(False)
+
     return BooleanValue(True)
 
 
 @register('compact')
 def compact(*args):
     """Returns a new list after removing any non-true values"""
-    ret = {}
-    if len(args) == 1:
+    sep = ','
+    if len(args) == 1 and isinstance(args[0], ListValue):
+        sep = args[0].value.get('_', '')
         args = args[0]
-        if isinstance(args, ListValue):
-            args = args.value
-        if isinstance(args, dict):
-            for i, item in args.items():
-                if isinstance(item, (basestring, StringValue)):
-                    if item != 'false' and not _undefined_re.match(unicode(item)):
-                        ret[i] = item
-                elif isinstance(item, (bool, BooleanValue)):
-                    if bool(item):
-                        ret[i] = item
-                else:
-                    ret[i] = item
-        elif isinstance(args, (basestring, StringValue)):
-            if args != 'false' and not _undefined_re.match(unicode(args)):
-                ret[0] = args
-        elif isinstance(args, (bool, BooleanValue)):
-            if bool(args):
-                ret[0] = args
-        else:
-            ret[0] = args
-    else:
-        ret['_'] = ','
-        for i, item in enumerate(args):
-            if isinstance(item, (basestring, StringValue)):
-                if item != 'false' and not _undefined_re.match(unicode(item)):
-                    ret[i] = item
-            elif isinstance(item, (bool, BooleanValue)):
-                if bool(item):
-                    ret[i] = item
-            else:
-                ret[i] = item
-    if isinstance(args, ListValue):
-        args = args.value
-    if isinstance(args, dict):
-        separator = args.get('_', None)
-        if separator is not None:
-            ret['_'] = separator
-    return ListValue(ret)
+
+    return ListValue(
+        [arg for arg in args if arg],
+        separator=sep,
+    )
 
 
 @register('reject')
diff --git a/scss/tests/functions/compass/test_helpers.py b/scss/tests/functions/compass/test_helpers.py
new file mode 100644
index 0000000..07a7b5c
--- /dev/null
+++ b/scss/tests/functions/compass/test_helpers.py
@@ -0,0 +1,45 @@
+"""Tests for the Compass helper functions.
+
+Not all of Compass is implemented, and the arrangement of Compass functions
+doesn't exactly match the arrangement in the original documentation.
+Regardless, this is a good starting place:
+
+http://compass-style.org/reference/compass/helpers/
+
+Some functions appear to be undocumented, but nonetheless are part of Compass's
+Ruby code.
+"""
+
+from scss.expression import Calculator
+from scss.functions.compass.helpers import COMPASS_HELPERS_LIBRARY
+from scss.rule import Namespace
+from scss.types import ColorValue, NumberValue
+
+import pytest
+xfail = pytest.mark.xfail
+
+# TODO many of these tests could also stand to test for failure cases
+
+@pytest.fixture
+def calc():
+    ns = Namespace(functions=COMPASS_HELPERS_LIBRARY)
+    return Calculator(ns).evaluate_expression
+
+# ------------------------------------------------------------------------------
+# Listish functions
+# See: http://ruby-doc.org/gems/docs/c/compass-0.12.2/Compass/SassExtensions/Functions/Lists.html
+
+def test_blank(calc):
+    assert calc('blank(false)')
+    assert calc('blank("")')
+    assert calc('blank(" ")')
+    # TODO this is a syntax error; see #166
+    #assert calc('blank(())')
+
+    assert not calc('blank(null)')  # yes, really
+    assert not calc('blank(1)')
+    assert not calc('blank((1, 2))')
+    assert not calc('blank(0)')
+
+def test_compact(calc):
+    assert calc('compact(1 2 3 false 4 5 null 6 7)') == calc('1 2 3 4 5 6 7')
diff --git a/scss/types.py b/scss/types.py
index c579efe..77e6b5c 100644
--- a/scss/types.py
+++ b/scss/types.py
@@ -40,7 +40,8 @@ class Value(object):
         return self._do_cmps(self, other, operator.__ge__)
 
     def __nonzero__(self):
-        return bool(self.value)
+        # Sass values are all true, except for booleans and nulls
+        return True
 
     def __add__(self, other):
         return self._do_op(self, other, operator.__add__)
@@ -83,6 +84,9 @@ class NullValue(Value):
     def __str__(self):
         return 'null'
 
+    def __nonzero__(self):
+        return False
+
 
 class BooleanValue(Value):
     def __init__(self, value):
@@ -94,6 +98,9 @@ class BooleanValue(Value):
     def __str__(self):
         return 'true' if self.value else 'false'
 
+    def __nonzero__(self):
+        return self.value
+
     @classmethod
     def _do_cmps(cls, first, second, op):
         return op(bool(first), bool(second))