fix: Reach 100% test coverage and fix edge cases

In detail:
fix: Fail on parts without header/data separator.
fix: Fail on completely empty parts.
fix: Fail on streams without end boundary.
fix: Do not fail if there is junk after end boundary.

multipart.py

@@ -42,8 +42,13 @@ class MultiDict(DictMixin):
 
     def __init__(self, *args, **kwargs):
         self.dict = {}
-        for k, v in args:
-            self[k] = v
+        for arg in args:
+            if hasattr(arg, 'items'):
+                for k, v in arg.items():
+                    self[k] = v
+            else:
+                for k, v in arg:
+                    self[k] = v
         for k, v in kwargs.items():
             self[k] = v
 
@@ -284,17 +289,13 @@ def _iterparse(self):
         # Consume first boundary. Ignore any preamble, as required by RFC
         # 2046, section 5.1.1.
         for line, nl in lines:
-            if line in (separator, terminator):
+            if line == separator:
                 break
+            if line == terminator:
+                return  # Empty form
         else:
             raise MultipartError("Stream does not contain boundary")
 
-        # Check for empty data
-        if line == terminator:
-            for _ in lines:
-                raise MultipartError("Data after end of stream")
-            return
-
         # For each part in stream...
         mem_used, disk_used = 0, 0  # Track used resources to prevent DoS
         is_tail = False  # True if the last line was incomplete (cutted)
@@ -309,7 +310,7 @@ def _iterparse(self):
 
         for line, nl in lines:
             if line == terminator and not is_tail:
-                part.file.seek(0)
+                part.end_part()
                 yield part
                 break
 
@@ -318,8 +319,8 @@ def _iterparse(self):
                     mem_used += part.size
                 else:
                     disk_used += part.size
-                part.file.seek(0)
 
+                part.end_part()
                 yield part
 
                 part = MultipartPart(**opts)
@@ -337,13 +338,9 @@ def _iterparse(self):
                 except MultipartError:
                     part.close()
                     raise
-        else:
-            # If we run off the end of the loop, the current MultipartPart
-            # will not have been yielded, so it's our responsibility to
-            # close it.
-            part.close()
 
         if line != terminator:
+            part.close()
             raise MultipartError("Unexpected end of multipart stream.")
 
 
@@ -368,6 +365,11 @@ def feed(self, line, nl=""):
 
         return self.write_header(line, nl)
 
+    def end_part(self):
+        if not self.file:
+            raise MultipartError("Unexpected end of part within header section.")
+        self.file.seek(0)
+
     def write_header(self, line, nl):
         line = line.decode(self.charset)
 
@@ -387,8 +389,8 @@ def write_header(self, line, nl):
             self.headerlist.append((name.strip(), value.strip()))
 
     def write_body(self, line, nl):
-        if not line and not nl:
-            return  # This does not even flush the buffer
+        if not line and not nl: # pragma: no cover
+            return  # No new data (should not happen)
 
         self.size += len(line) + len(self._buf)
         self.file.write(self._buf + line)
@@ -431,17 +433,12 @@ def value(self):
 
     @property
     def raw(self):
-        """ Data without decoding """
+        """ Raw binary data """
         pos = self.file.tell()
         self.file.seek(0)
 
-        try:
-            val = self.file.read()
-        except IOError:
-            raise
-        finally:
-            self.file.seek(pos)
-
+        val = self.file.read()
+        self.file.seek(pos)
         return val
 
     def save_as(self, path):

test/test_multdict.py

@@ -0,0 +1,52 @@
+# -*- coding: utf-8 -*-
+import unittest
+import os.path, tempfile
+
+import multipart as mp
+
+class testMultiDict(unittest.TestCase):
+
+    def test_init(self):
+        md = mp.MultiDict([("a", "1")], {"a": "2"}, a="3")
+        self.assertEqual(md.dict, {"a": ["1", "2", "3"]})
+
+    def test_append(self):
+        md = mp.MultiDict()
+        md["a"] = "1"
+        md["a"] = "2"
+        md.append("a", "3")
+        md.update(a="4")
+        self.assertEqual(md.dict, {"a": ["1", "2", "3", "4"]})
+
+    def test_behaves_like_dict(self):
+        md = mp.MultiDict([("a", "1"), ("a", "2")])
+        self.assertTrue("a" in md)
+        self.assertFalse("b" in md)
+        self.assertTrue("a" in md.keys())
+        del md["a"]
+        self.assertTrue("a" not in md)
+
+    def test_access_last(self):
+        md = mp.MultiDict([("a", "1"), ("a", "2")])
+        self.assertEqual(md["a"], "2")
+        self.assertEqual(md.get("a"), "2")
+        self.assertEqual(md.get("b"), None)
+
+    def test_replace(self):
+        md = mp.MultiDict([("a", "1"), ("a", "2")])
+        md.replace("a", "3")
+        self.assertEqual(md.dict, {"a": ["3"]})
+
+    def test_str_repr(self):
+        md = mp.MultiDict([("a", "1"), ("a", "2")])
+        self.assertEqual(str(md), str(md.dict))
+        self.assertEqual(repr(md), repr(md.dict))
+
+    def test_access_index(self):
+        md = mp.MultiDict([("a", "1"), ("a", "2")])
+        self.assertEqual(md.get("a", index=0), "1")
+
+    def test_access_all(self):
+        md = mp.MultiDict([("a", "1"), ("a", "2")])
+        self.assertEqual(md.getall("a"), ["1", "2"])
+        self.assertEqual(list(md.iterallitems()), [("a", "1"),("a", "2")])

test/test_multipart.py

@@ -1,15 +1,11 @@
 # -*- coding: utf-8 -*-
 import unittest
 import base64
-import sys, os.path, tempfile
+import os.path, tempfile
 
 from io import BytesIO
 
-try:
-    import multipart as mp
-except ModuleNotFoundError:
-    raise SystemExit("multipart not resolveable. Try 'python setup.py develop'.")
-
+import multipart as mp
 from multipart import to_bytes
 
 #TODO: bufsize=10, line=1234567890--boundary\n
@@ -260,6 +256,7 @@ def setUp(self):
                     'wsgi.input': self.data}
 
     def write(self, *lines):
+        self.data.truncate(0)
         for line in lines:
             self.data.write(to_bytes(line))
 
@@ -304,6 +301,14 @@ def test_missing_boundary(self):
         self.env['CONTENT_TYPE'] = 'multipart/form-data'
         self.assertMPError()
 
+    def test_part_ends_after_header(self):
+        self.write('--foo\r\n', 'Header: value\r\n', '--foo--')
+        self.assertMPError()
+
+    def test_part_ends_in_header(self):
+        self.write('--foo\r\n', 'Header: value', '--foo--')
+        self.assertMPError()
+
     def test_no_terminator(self):
         self.write('--foo\r\n',
                    'Content-Disposition: form-data; name="file1"; filename="random.png"\r\n',
@@ -325,7 +330,7 @@ def test_no_newline_after_middle_content(self):
         self.assertEqual(len(files), 1)
         self.assertTrue(to_bytes('name="file2"') in files['file1'].file.read())
 
-    def test_preamble_before_start_boundary(self):
+    def test_ignore_junk_before_start_boundary(self):
         forms, files = self.parse('Preamble\r\n', '--foo\r\n'
                    'Content-Disposition: form-data; name="file1"; filename="random.png"\r\n',
                    'Content-Type: image/png\r\n', '\r\n', 'abc\r\n', '--foo--')
@@ -334,12 +339,33 @@ def test_preamble_before_start_boundary(self):
         self.assertEqual(files['file1'].name, 'file1')
         self.assertEqual(files['file1'].content_type, 'image/png')
 
+    def test_allow_junk_after_end_boundary(self):
+        self.parse('--foo--\r\njunk')
+        self.parse('--foo\r\n'
+                   'Content-Disposition: form-data; name="file1"; filename="random.png"\r\n',
+                   'Content-Type: image/png\r\n', '\r\n', 'abc\r\n', '--foo--\r\n', 'junk') 
+
     def test_no_start_boundary(self):
         self.write('--bar\r\n','--nonsense\r\n'
                    'Content-Disposition: form-data; name="file1"; filename="random.png"\r\n',
                    'Content-Type: image/png\r\n', '\r\n', 'abc\r\n', '--nonsense--')
         self.assertMPError()
 
+    def test_no_end_boundary(self):
+        self.write('--foo\r\n',
+                   'Content-Disposition: form-data; name="file1"; filename="random.png"\r\n',
+                   'Content-Type: image/png\r\n', '\r\n', 'abc\r\n')
+        self.assertMPError()
+
+    def test_just_end_boundary(self):
+        files, forms = self.parse('--foo--') # is fine
+        self.assertTrue(not files)
+        self.assertTrue(not forms)
+
+    def test_empty_part(self):
+        self.write('--foo\r\n', '--foo--')
+        self.assertMPError()
+
     def test_disk_limit(self):
         self.write('--foo\r\n',
                    'Content-Disposition: form-data; name="file1"; filename="random.png"\r\n',