Enable Python warnings during tests and fix all in the code

When running the test suite with Python warnings enabled, several
warnings are emitted. They look like:

    tests/test_utils.py::test_format_requirement
      /usr/lib64/python3.9/tempfile.py:817: ResourceWarning: Implicitly cleaning up <TemporaryDirectory '/tmp/tmpezxehep1source'>
        _warnings.warn(warn_message, ResourceWarning)

To solve, make Repository.freshen_build_caches() a context manager. Upon
entering the with statement, the build an source caches are created and
upon exit they are cleaned up. This ensures they only live for the
duration they are required. Tests were adjusted.

    tests/test_repository_pypi.py::test_pypirepo_build_dir_is_str
      .../pip/_vendor/requests/adapters.py:59: ResourceWarning: unclosed file <_io.FileIO name='/tmp/pytest-of-jon/pytest-70/test_open_local_or_remote_file5/foo.txt' mode='rb' closefd=True>
        super(BaseAdapter, self).__init__()

To solve, test_open_local_or_remote_file_remote_file() was adjusted to
close its file after use.

    tests/test_cli_compile.py::test_redacted_urls_in_verbose_output[--find-links]
      .../pip-tools/piptools/scripts/compile.py:306: FutureWarning: --index and --no-index are deprecated and will be removed in future versions. Use --emit-index-url/--no-emit-index-url instead.
        warnings.warn(

To solve, use --no-emit-index-url in
test_redacted_urls_in_verbose_output().

There remains one warning left, but this is out of the control of
pip-tools. An upstream PR has been filed:
pypa/pip#9156

Enabling the warnings in test runs will help catch them earlier and make
debugging/fixing easier.

piptools/repositories/base.py

@@ -12,6 +12,8 @@ class BaseRepository(object):
     def clear_caches(self):
         """Should clear any caches used by the implementation."""
 
+    @abstractmethod
+    @contextmanager
     def freshen_build_caches(self):
         """Should start with fresh build/source caches."""
 

piptools/repositories/local.py

@@ -56,8 +56,10 @@ def DEFAULT_INDEX_URL(self):
     def clear_caches(self):
         self.repository.clear_caches()
 
+    @contextmanager
     def freshen_build_caches(self):
-        self.repository.freshen_build_caches()
+        with self.repository.freshen_build_caches():
+            yield
 
     def find_best_match(self, ireq, prereleases=None):
         key = key_from_ireq(ireq)

piptools/repositories/pypi.py

@@ -87,29 +87,38 @@ def __init__(self, pip_args, cache_dir):
         self._dependencies_cache = {}
 
         # Setup file paths
-        self.freshen_build_caches()
+        self._build_dir = None
+        self._source_dir = None
         self._cache_dir = normalize_path(cache_dir)
         self._download_dir = fs_str(os.path.join(self._cache_dir, "pkgs"))
         if PIP_VERSION[:2] <= (20, 2):
             self._wheel_download_dir = fs_str(os.path.join(self._cache_dir, "wheels"))
 
         self._setup_logging()
 
+    @contextmanager
     def freshen_build_caches(self):
         """
         Start with fresh build/source caches.  Will remove any old build
         caches from disk automatically.
         """
         self._build_dir = TemporaryDirectory(fs_str("build"))
         self._source_dir = TemporaryDirectory(fs_str("source"))
+        try:
+            yield
+        finally:
+            self._build_dir.cleanup()
+            self._build_dir = None
+            self._source_dir.cleanup()
+            self._source_dir = None
 
     @property
     def build_dir(self):
-        return self._build_dir.name
+        return self._build_dir.name if self._build_dir else None
 
     @property
     def source_dir(self):
-        return self._source_dir.name
+        return self._source_dir.name if self._source_dir else None
 
     def clear_caches(self):
         rmtree(self._download_dir, ignore_errors=True)

piptools/resolver.py

@@ -170,7 +170,13 @@ def resolve(self, max_rounds=10):
 
             log.debug("")
             log.debug(magenta("{:^60}".format("ROUND {}".format(current_round))))
-            has_changed, best_matches = self._resolve_one_round()
+            # If a package version (foo==2.0) was built in a previous round,
+            # and in this round a different version of foo needs to be built
+            # (i.e. foo==1.0), the directory will exist already, which will
+            # cause a pip build failure.  The trick is to start with a new
+            # build cache dir for every round, so this can never happen.
+            with self.repository.freshen_build_caches():
+                has_changed, best_matches = self._resolve_one_round()
             log.debug("-" * 60)
             log.debug(
                 "Result of round {}: {}".format(
@@ -180,13 +186,6 @@ def resolve(self, max_rounds=10):
             if not has_changed:
                 break
 
-            # If a package version (foo==2.0) was built in a previous round,
-            # and in this round a different version of foo needs to be built
-            # (i.e. foo==1.0), the directory will exist already, which will
-            # cause a pip build failure.  The trick is to start with a new
-            # build cache dir for every round, so this can never happen.
-            self.repository.freshen_build_caches()
-
         del os.environ["PIP_EXISTS_ACTION"]
 
         # Only include hard requirements and not pip constraints

setup.cfg

@@ -56,6 +56,7 @@ universal = 1
 norecursedirs = .* build dist venv test_data piptools/_compat/*
 testpaths = tests piptools
 filterwarnings =
+    always
     ignore::PendingDeprecationWarning:pip\._vendor.+
     ignore::DeprecationWarning:pip\._vendor.+
 markers =

tests/conftest.py

@@ -41,6 +41,10 @@ def __init__(self):
         with open("tests/test_data/fake-editables.json", "r") as f:
             self.editables = json.load(f)
 
+    @contextmanager
+    def freshen_build_caches(self):
+        yield
+
     def get_hashes(self, ireq):
         # Some fake hashes
         return {

tests/test_cli_compile.py

@@ -196,7 +196,7 @@ def test_redacted_urls_in_verbose_output(runner, option):
         cli,
         [
             "--no-header",
-            "--no-index",
+            "--no-emit-index-url",
             "--no-emit-find-links",
             "--verbose",
             option,

tests/test_repository_pypi.py

@@ -109,23 +109,30 @@ def test_open_local_or_remote_file__remote_file(
     response_file_path.write_bytes(content)
 
     mock_response = mock.Mock()
-    mock_response.raw = response_file_path.open("rb")
-    mock_response.headers = {"content-length": content_length}
+    with response_file_path.open("rb") as fp:
+        mock_response.raw = fp
+        mock_response.headers = {"content-length": content_length}
 
-    with mock.patch.object(session, "get", return_value=mock_response):
-        with open_local_or_remote_file(link, session) as file_stream:
-            assert file_stream.stream.read() == content
-            assert file_stream.size == expected_content_length
+        with mock.patch.object(session, "get", return_value=mock_response):
+            with open_local_or_remote_file(link, session) as file_stream:
+                assert file_stream.stream.read() == content
+                assert file_stream.size == expected_content_length
 
-    mock_response.close.assert_called_once()
+        mock_response.close.assert_called_once()
 
 
 def test_pypirepo_build_dir_is_str(pypi_repository):
-    assert isinstance(pypi_repository.build_dir, str)
+    assert pypi_repository.build_dir is None
+    with pypi_repository.freshen_build_caches():
+        assert isinstance(pypi_repository.build_dir, str)
+    assert pypi_repository.build_dir is None
 
 
 def test_pypirepo_source_dir_is_str(pypi_repository):
-    assert isinstance(pypi_repository.source_dir, str)
+    assert pypi_repository.source_dir is None
+    with pypi_repository.freshen_build_caches():
+        assert isinstance(pypi_repository.source_dir, str)
+    assert pypi_repository.source_dir is None
 
 
 def test_relative_path_cache_dir_is_normalized(from_line):