Replaced overly-specific error messages with more general ones for improved...

Replaced overly-specific error messages with more general ones for improved cross-implementation compatibility. Fixes #50.

CHANGES.txt

@@ -11,6 +11,8 @@ CHANGES
   `pkg_resources.invalid_marker`. Any clients depending on the specific
   string representation of exceptions returned by that function may need to
   be updated to account for this change.
+* Issue #50: SyntaxErrors generated by `pkg_resources.invalid_marker` are
+  normalized for cross-implementation consistency.
 
 -----
 0.9.8

pkg_resources.py

@@ -1271,9 +1271,15 @@ def normalize_exception(exc):
     """
     Given a SyntaxError from a marker evaluation, normalize the error message:
      - Remove indications of filename and line number.
+     - Replace platform-specific error messages with standard error messages.
     """
+    subs = {
+        'unexpected EOF while parsing': 'invalid syntax',
+        'parenthesis is never closed': 'invalid syntax',
+    }
     exc.filename = None
     exc.lineno = None
+    exc.msg = subs.get(exc.msg, exc.msg)
     return exc
 
 

tests/api_tests.txt

@@ -342,7 +342,7 @@ Environment Markers
     Comparison or logical expression expected
 
     >>> print(im("sys_platform=="))
-    unexpected EOF while parsing
+    invalid syntax
 
     >>> print(im("sys_platform=='win32'"))
     False
@@ -354,7 +354,7 @@ Environment Markers
     Comparison or logical expression expected
 
     >>> print(im("(extra"))
-    unexpected EOF while parsing
+    invalid syntax
 
     >>> print(im("os.open('foo')=='y'"))
     Language feature not supported in environment markers