Add merge_paths function and tests for it

rfc3986/misc.py

@@ -197,3 +197,14 @@ hier_part = '(//%s%s|%s|%s|%s)' % (
 ABSOLUTE_URI_MATCHER = re.compile('^%s:%s(\?%s)$' % (
     component_pattern_dict['scheme'], hier_part, QUERY_MATCHER.pattern
     ))
+
+
+# Path merger as defined in http://tools.ietf.org/html/rfc3986#section-5.2.3
+def merge_paths(base_uri, relative_path):
+    """Merge a base URI's path with a relative URI's path."""
+    if base_uri.path is None and base_uri.authority is not None:
+        return '/' + relative_path
+    else:
+        path = base_uri.path or ''
+        index = path.rfind('/')
+        return path[:index] + '/' + relative_path

tests/test_misc.py

@@ -0,0 +1,47 @@
+# -*- coding: utf-8 -*-
+from rfc3986.uri import URIReference
+from rfc3986.misc import merge_paths
+
+
+def test_merge_paths_with_base_path_without_base_authority():
+    """Demonstrate merging with a base URI without an authority."""
+    base = URIReference(scheme=None,
+                        authority=None,
+                        path='/foo/bar/bogus',
+                        query=None,
+                        fragment=None)
+    expected = '/foo/bar/relative'
+    assert merge_paths(base, 'relative') == expected
+
+
+def test_merge_paths_with_base_authority_and_path():
+    """Demonstrate merging with a base URI with an authority and path."""
+    base = URIReference(scheme=None,
+                        authority='authority',
+                        path='/foo/bar/bogus',
+                        query=None,
+                        fragment=None)
+    expected = '/foo/bar/relative'
+    assert merge_paths(base, 'relative') == expected
+
+
+def test_merge_paths_without_base_authority_or_path():
+    """Demonstrate merging with a base URI without an authority or path."""
+    base = URIReference(scheme=None,
+                        authority=None,
+                        path=None,
+                        query=None,
+                        fragment=None)
+    expected = '/relative'
+    assert merge_paths(base, 'relative') == expected
+
+
+def test_merge_paths_with_base_authority_without_path():
+    """Demonstrate merging with a base URI without an authority or path."""
+    base = URIReference(scheme=None,
+                        authority='authority',
+                        path=None,
+                        query=None,
+                        fragment=None)
+    expected = '/relative'
+    assert merge_paths(base, 'relative') == expected