lock: do not emit relative paths when writing to stdout

Author: sbidoul

src/pip/_internal/commands/lock.py

@@ -152,7 +152,11 @@ def run(self, options: Values, args: List[str]) -> int:
         requirement_set = resolver.resolve(reqs, check_supported_wheels=True)
 
         if options.output_file == "-":
-            base_dir = Path.cwd()
+            # The pylock spec says "If a relative path is used it MUST be
+            # relative to the location of this file". When writing to stdout, we
+            # don't have a location for the file, so we can't use a relative
+            # path.
+            base_dir = None
         else:
             output_file_path = Path(options.output_file)
             if not is_valid_pylock_path(output_file_path):

src/pip/_internal/utils/pylock.py

@@ -1,5 +1,5 @@
 from pathlib import Path
-from typing import Iterable
+from typing import Iterable, Optional
 
 from pip._vendor import tomli_w
 from pip._vendor.packaging.version import Version
@@ -20,9 +20,10 @@
 
 
 def _pylock_package_from_install_requirement(
-    ireq: InstallRequirement, base_dir: Path
+    ireq: InstallRequirement, base_dir: Optional[Path]
 ) -> Package:
-    base_dir = base_dir.resolve()
+    if base_dir is not None:
+        base_dir = base_dir.resolve()
     dist = ireq.get_dist()
     download_info = ireq.download_info
     assert download_info
@@ -45,10 +46,14 @@ def _pylock_package_from_install_requirement(
         elif isinstance(download_info.info, DirInfo):
             package_directory = PackageDirectory(
                 path=(
-                    Path(url_to_path(download_info.url))
-                    .resolve()
-                    .relative_to(base_dir)
-                    .as_posix()
+                    (
+                        Path(url_to_path(download_info.url))
+                        .resolve()
+                        .relative_to(base_dir)
+                        .as_posix()
+                    )
+                    if base_dir is not None
+                    else url_to_path(download_info.url)
                 ),
                 editable=(
                     download_info.info.editable if download_info.info.editable else None
@@ -102,7 +107,7 @@ def _pylock_package_from_install_requirement(
 
 
 def pylock_from_install_requirements(
-    install_requirements: Iterable[InstallRequirement], base_dir: Path
+    install_requirements: Iterable[InstallRequirement], base_dir: Optional[Path]
 ) -> Pylock:
     return Pylock(
         lock_version=Version("1.0"),