Add create_accept_header, docs and tests.

3 files changed, 45 insertions, 0 deletions

diff --git a/docs/api/webob.txt b/docs/api/webob.txt
index 2f3111d..b3905ba 100644
--- a/docs/api/webob.txt
+++ b/docs/api/webob.txt
@@ -9,6 +9,8 @@ Accept-*
 .. automodule:: webob.acceptparse
 
 
+.. autofunction:: create_accept_header
+
 .. autoclass:: Accept
    :members: parse
 
diff --git a/src/webob/acceptparse.py b/src/webob/acceptparse.py
index d2b6007..02c0cb6 100644
--- a/src/webob/acceptparse.py
+++ b/src/webob/acceptparse.py
@@ -1485,6 +1485,28 @@ class AcceptInvalidHeader(_AcceptInvalidOrNoHeader):
             return AcceptNoHeader()
 
 
+def create_accept_header(header_value):
+    """
+    Create an object representing the ``Accept`` header in a request.
+
+    :param header_value: (``str``) header value
+    :return: If `header_value` is ``None``, an :class:`AcceptNoHeader`
+             instance.
+
+             | If `header_value` is a valid ``Accept`` header, an
+               :class:`AcceptValidHeader` instance.
+
+             | If `header_value` is an invalid ``Accept`` header, an
+               :class:`AcceptInvalidHeader` instance.
+    """
+    if header_value is None:
+        return AcceptNoHeader()
+    try:
+        return AcceptValidHeader(header_value=header_value)
+    except ValueError:
+        return AcceptInvalidHeader(header_value=header_value)
+
+
 class NilAccept(object):
     """
     Represents a generic ``Accept-*`` style header when it is not present in
diff --git a/tests/test_acceptparse.py b/tests/test_acceptparse.py
index 49f3f37..a8c435e 100644
--- a/tests/test_acceptparse.py
+++ b/tests/test_acceptparse.py
@@ -27,6 +27,7 @@ from webob.acceptparse import (
     accept_property,
     create_accept_charset_header,
     create_accept_encoding_header,
+    create_accept_header,
     create_accept_language_header,
     MIMEAccept,
     NilAccept,
@@ -2230,6 +2231,26 @@ class TestAcceptInvalidHeader(object):
         assert returned == 1.0
 
 
+class TestCreateAcceptHeader(object):
+    def test_header_value_is_None(self):
+        header_value = None
+        returned = create_accept_header(header_value=header_value)
+        assert isinstance(returned, AcceptNoHeader)
+        assert returned.header_value == header_value
+
+    def test_header_value_is_valid(self):
+        header_value = 'text/html, text/plain;q=0.9'
+        returned = create_accept_header(header_value=header_value)
+        assert isinstance(returned, AcceptValidHeader)
+        assert returned.header_value == header_value
+
+    @pytest.mark.parametrize('header_value', [', ', 'noslash'])
+    def test_header_value_is_invalid(self, header_value):
+        returned = create_accept_header(header_value=header_value)
+        assert isinstance(returned, AcceptInvalidHeader)
+        assert returned.header_value == header_value
+
+
 class TestAcceptCharset(object):
     @pytest.mark.parametrize('value', [
         '',