Add --skip-existing flag to upload command

tests/test_upload.py

@@ -16,9 +16,14 @@
 import os
 import textwrap
 
+import pretend
 import pytest
 
 from twine.commands import upload
+from twine import package
+
+
+WHEEL_FIXTURE = 'tests/fixtures/twine-1.5.0-py2.py3-none-any.whl'
 
 
 def test_ensure_wheel_files_uploaded_first():
@@ -72,11 +77,35 @@ def test_get_config_old_format(tmpdir):
     try:
         upload.upload(dists="foo", repository="pypi", sign=None, identity=None,
                       username=None, password=None, comment=None,
-                      sign_with=None, config_file=pypirc)
+                      sign_with=None, config_file=pypirc, skip_existing=False)
     except KeyError as err:
         assert err.args[0] == (
             "Missing 'pypi' section from the configuration file.\n"
             "Maybe you have a out-dated '{0}' format?\n"
             "more info: "
             "https://docs.python.org/distutils/packageindex.html#pypirc\n"
         ).format(pypirc)
+
+
+def test_skip_existing_skips_files_already_on_PyPI(monkeypatch):
+    response = pretend.stub(
+        status_code=400,
+        reason='A file named "twine-1.5.0-py2.py3-none-any.whl" already '
+               'exists for twine-1.5.0.')
+
+    pkg = package.PackageFile.from_filename(WHEEL_FIXTURE, None)
+    assert upload.skip_upload(response=response,
+                              skip_existing=True,
+                              package=pkg) is True
+
+
+def test_skip_upload_respects_skip_existing(monkeypatch):
+    response = pretend.stub(
+        status_code=400,
+        reason='A file named "twine-1.5.0-py2.py3-none-any.whl" already '
+               'exists for twine-1.5.0.')
+
+    pkg = package.PackageFile.from_filename(WHEEL_FIXTURE, None)
+    assert upload.skip_upload(response=response,
+                              skip_existing=False,
+                              package=pkg) is False

twine/commands/upload.py

@@ -53,8 +53,16 @@ def find_dists(dists):
     return group_wheel_files_first(uploads)
 
 
+def skip_upload(response, skip_existing, package):
+    filename = package.basefilename
+    msg = 'A file named "{0}" already exists for'.format(filename)
+    return (response.status_code == 400 and
+            response.reason.startswith(msg) and
+            skip_existing)
+
+
 def upload(dists, repository, sign, identity, username, password, comment,
-           sign_with, config_file):
+           sign_with, config_file, skip_existing):
     # Check that a nonsensical option wasn't given
     if not sign and identity:
         raise ValueError("sign must be given along with identity")
@@ -106,9 +114,15 @@ def upload(dists, repository, sign, identity, username, password, comment,
         if resp.is_redirect:
             raise exc.RedirectDetected(
                 ('"{0}" attempted to redirect to "{1}" during upload.'
-                 ' Aborting...').format(config["respository"],
+                 ' Aborting...').format(config["repository"],
                                         resp.headers["location"]))
+
         # Otherwise, raise an HTTPError based on the status code.
+        if skip_upload(resp, skip_existing, package):
+            print("  Skipping {0} because it appears to already exist".format(
+                package.basefilename))
+            continue
+
         resp.raise_for_status()
 
     # Bug 28. Try to silence a ResourceWarning by clearing the connection
@@ -155,6 +169,12 @@ def main(args):
         default="~/.pypirc",
         help="The .pypirc config file to use",
     )
+    parser.add_argument(
+        "--skip-existing",
+        default=False,
+        action="store_true",
+        help="Continue uploading files if one already exists",
+    )
     parser.add_argument(
         "dists",
         nargs="+",