Fix for sync error when the ireqs being merged have no names (#1802)

* Fix for sync error when the ireqs being merged have no names

When no name was provided, the ireqs would have no underlying req
attribute. Calling ireq.specifier would raise an AttributeError.

* Integration test for merging requirements without names

piptools/sync.py

@@ -104,7 +104,11 @@ def merge(
                 if existing_ireq:
                     # NOTE: We check equality here since we can assume that the
                     # requirements are all pinned
-                    if ireq.specifier != existing_ireq.specifier:
+                    if (
+                        ireq.req
+                        and existing_ireq.req
+                        and ireq.specifier != existing_ireq.specifier
+                    ):
                         raise IncompatibleRequirements(ireq, existing_ireq)
 
             # TODO: Always pick the largest specifier in case of a conflict

tests/test_cli_sync.py

@@ -3,6 +3,7 @@
 import os
 import subprocess
 import sys
+from pathlib import Path
 from unittest import mock
 
 import pytest
@@ -128,6 +129,31 @@ def test_merge_error(req_lines, should_raise, runner):
         assert out.exit_code == 1
 
 
+@pytest.mark.parametrize(
+    "req_line",
+    (
+        "file:.",
+        "-e file:.",
+    ),
+)
+@mock.patch("piptools.sync.run")
+def test_merge_no_name_urls(run, req_line, runner):
+    """
+    Test sync succeeds when merging requirements that lack names.
+    """
+    reqs_paths = [
+        Path(name).absolute() for name in ("requirements.txt", "dev_requirements.txt")
+    ]
+
+    for reqs_path in reqs_paths:
+        with reqs_path.open("w") as req_out:
+            req_out.write(f"{req_line} \n")
+
+    out = runner.invoke(cli, [str(path) for path in reqs_paths])
+    assert out.exit_code == 0
+    assert run.call_count == 2
+
+
 @pytest.mark.parametrize(
     ("cli_flags", "expected_install_flags"),
     (

tests/test_sync.py

@@ -115,6 +115,26 @@ def test_merge_urls(from_line):
     )
 
 
+@pytest.mark.parametrize(
+    "install_req",
+    (
+        "from_line",
+        "from_editable",
+    ),
+)
+def test_merge_no_name_urls(install_req, request):
+    install_req = request.getfixturevalue(install_req)
+    url = "file:///example.zip"
+    requirements = [
+        install_req(url),
+        install_req(url),
+    ]
+
+    assert Counter(requirements[1:]) == Counter(
+        merge(requirements, ignore_conflicts=False)
+    )
+
+
 def test_diff_should_do_nothing():
     installed = []  # empty env
     reqs = []  # no requirements