add a test

tests/constants.py

@@ -5,3 +5,6 @@
 TEST_DATA_PATH = os.path.join(os.path.dirname(__file__), "test_data")
 MINIMAL_WHEELS_PATH = os.path.join(TEST_DATA_PATH, "minimal_wheels")
 PACKAGES_PATH = os.path.join(TEST_DATA_PATH, "packages")
+PACKAGES_RELATIVE_PATH = os.path.relpath(
+    PACKAGES_PATH, os.path.commonpath([os.getcwd(), PACKAGES_PATH])
+)

tests/test_pip_compat.py

@@ -0,0 +1,31 @@
+from __future__ import annotations
+
+import os
+import tempfile
+
+import pytest
+
+from piptools._compat.pip_compat import parse_requirements
+from piptools.repositories import PyPIRepository
+
+from .constants import PACKAGES_RELATIVE_PATH
+
+
+@pytest.fixture
+def repository():
+    with tempfile.TemporaryDirectory() as cache_dir:
+        yield PyPIRepository([], cache_dir=cache_dir)
+
+
+def test_parse_requirements_preserve_editable_relative(repository):
+    test_package_path = os.path.join(PACKAGES_RELATIVE_PATH, "small_fake_a")
+
+    with tempfile.NamedTemporaryFile("w") as infile:
+        infile.write(f"-e {test_package_path}")
+        infile.flush()
+        [install_requirement] = parse_requirements(
+            infile.name, session=repository.session
+        )
+
+    assert install_requirement.link.url == test_package_path
+    assert install_requirement.link.file_path == test_package_path