Updating the Validation logic to truncate the string of val if it exc…

…eeds 1000 characters. Also redacting email address value if it's determined that we're pattern matching against an email regex. (#330)

* Truncating the value strings used in ValidationError Exception

* Redacting Error message if it's pattern matching against an email

* fixing linter message string length issues

* fixing mypy

* fixing doc string

stone/backends/python_rsrc/stone_validators.py

@@ -91,6 +91,17 @@ def generic_type_name(v):
         return type_name_with_module(type(v))
 
 
+def get_value_string(v, max_length=1000):
+    # type: (typing.Any, int) -> str
+    """Return a truncated version of the input string.  If the input string is longer than
+       1000 characters, this will return the first 1000 characters and append with '[The
+       string has been truncated due to its length]' to indicate that it has been truncated."""
+    v_str = str(v)
+    if len(v_str) > max_length:
+        return v_str[:max_length] + ' [The string has been truncated due to its length]'
+    return v_str
+
+
 class Validator(metaclass=ABCMeta):
     """All primitive and composite data types should be a subclass of this."""
     __slots__ = ("_redact",)
@@ -322,7 +333,7 @@ def validate(self, val):
         """
         if not isinstance(val, str):
             raise ValidationError("'%s' expected to be a string, got %s"
-                                  % (val, generic_type_name(val)))
+                                  % (get_value_string(val), generic_type_name(val)))
         if not six.PY3 and isinstance(val, str):
             try:
                 val = val.decode('utf-8')
@@ -331,14 +342,18 @@ def validate(self, val):
 
         if self.max_length is not None and len(val) > self.max_length:
             raise ValidationError("'%s' must be at most %d characters, got %d"
-                                  % (val, self.max_length, len(val)))
+                                  % (get_value_string(val), self.max_length, len(val)))
         if self.min_length is not None and len(val) < self.min_length:
             raise ValidationError("'%s' must be at least %d characters, got %d"
-                                  % (val, self.min_length, len(val)))
+                                  % (get_value_string(val), self.min_length, len(val)))
 
         if self.pattern and not self.pattern_re.match(val):
+            # Detect if pattern is matching an email address and return redacted error message.
+            if self.pattern == "^['#&A-Za-z0-9._%+-]+@[A-Za-z0-9-][A-Za-z0-9.-]*\\.[A-Za-z]{2,15}$":
+                val = "*****"
+
             raise ValidationError("'%s' did not match pattern '%s'"
-                                  % (val, self.pattern))
+                                  % (get_value_string(val), self.pattern))
         return val
 
 
@@ -366,10 +381,10 @@ def validate(self, val):
                                   % generic_type_name(val))
         elif self.max_length is not None and len(val) > self.max_length:
             raise ValidationError("'%s' must have at most %d bytes, got %d"
-                                  % (val, self.max_length, len(val)))
+                                  % (get_value_string(val), self.max_length, len(val)))
         elif self.min_length is not None and len(val) < self.min_length:
             raise ValidationError("'%s' has fewer than %d bytes, got %d"
-                                  % (val, self.min_length, len(val)))
+                                  % (get_value_string(val), self.min_length, len(val)))
         return val
 
 
@@ -425,13 +440,13 @@ def __init__(self, item_validator, min_items=None, max_items=None):
 
     def validate(self, val):
         if not isinstance(val, (tuple, list)):
-            raise ValidationError('%r is not a valid list' % val)
+            raise ValidationError('%r is not a valid list' % get_value_string(val))
         elif self.max_items is not None and len(val) > self.max_items:
             raise ValidationError('%r has more than %s items'
-                                  % (val, self.max_items))
+                                  % (get_value_string(val), self.max_items))
         elif self.min_items is not None and len(val) < self.min_items:
             raise ValidationError('%r has fewer than %s items'
-                                  % (val, self.min_items))
+                                  % (get_value_string(val), self.min_items))
         return [self.item_validator.validate(item) for item in val]
 
 
@@ -449,7 +464,7 @@ def __init__(self, key_validator, value_validator):
 
     def validate(self, val):
         if not isinstance(val, dict):
-            raise ValidationError('%r is not a valid dict' % val)
+            raise ValidationError('%r is not a valid dict' % get_value_string(val))
         return {
             self.key_validator.validate(key):
                 self.value_validator.validate(value) for key, value in val.items()