Fix [ 3606028 ] ``assert`` is skipped with ``python -O``.

Also, raise ValueError with list of valid units if
length_or_percentage_or_unitless() fails.

git-svn-id: http://svn.code.sf.net/p/docutils/code/trunk/docutils@7621 929543f6-e4f2-0310-98a6-ba3bd3dd1d04

3 files changed, 26 insertions, 3 deletions

diff --git a/HISTORY.txt b/HISTORY.txt
index 544a23268..eb9bb8f60 100644
--- a/HISTORY.txt
+++ b/HISTORY.txt
@@ -25,6 +25,10 @@ Changes Since 0.10
 
   - Fix [ 3601607 ] node.__repr__() must return `str` instance.
 
+* docutils/parsers/rst/directives/__init__.py
+
+  - Fix [ 3606028 ] ``assert`` is skipped with ``python -O``.
+
 * docutils/parsers/rst/directives/images.py
 
   - Apply [ 3599485 ] node source/line information for sphinx translation.
diff --git a/docutils/parsers/rst/directives/__init__.py b/docutils/parsers/rst/directives/__init__.py
index fdc70d70f..ee919dd6f 100644
--- a/docutils/parsers/rst/directives/__init__.py
+++ b/docutils/parsers/rst/directives/__init__.py
@@ -232,9 +232,8 @@ def get_measure(argument, units):
     """
     match = re.match(r'^([0-9.]+) *(%s)$' % '|'.join(units), argument)
     try:
-        assert match is not None
         float(match.group(1))
-    except (AssertionError, ValueError):
+    except (AttributeError, ValueError):
         raise ValueError(
             'not a positive measure of one of the following units:\n%s'
             % ' '.join(['"%s"' % i for i in units]))
@@ -262,7 +261,11 @@ def length_or_percentage_or_unitless(argument, default=''):
     try:
         return get_measure(argument, length_units + ['%'])
     except ValueError:
-        return get_measure(argument, ['']) + default
+        try:
+            return get_measure(argument, ['']) + default
+        except ValueError:
+            # raise ValueError with list of valid units:
+            return get_measure(argument, length_units + ['%'])
 
 def class_option(argument):
     """
diff --git a/test/test_parsers/test_rst/test_directives/test_images.py b/test/test_parsers/test_rst/test_directives/test_images.py
index 67d898eb4..ea3adfa8f 100755
--- a/test/test_parsers/test_rst/test_directives/test_images.py
+++ b/test/test_parsers/test_rst/test_directives/test_images.py
@@ -164,6 +164,22 @@ totest['images'] = [
 """],
 ["""\
 .. image:: picture.png
+   :width: 20mc
+""",
+"""\
+<document source="test data">
+    <system_message level="3" line="1" source="test data" type="ERROR">
+        <paragraph>
+            Error in "image" directive:
+            invalid option value: (option: "width"; value: \'20mc\')
+            not a positive measure of one of the following units:
+            "em" "ex" "px" "in" "cm" "mm" "pt" "pc" "%".
+        <literal_block xml:space="preserve">
+            .. image:: picture.png
+               :width: 20mc
+"""],
+["""\
+.. image:: picture.png
    :height: 100
    :width: 200
    :scale: 50