Adds support for multiple requirements for a single package name (#12232

)

Closes #12186 by grouping requirements that reference the same pip dependency name.

[ci skip-build-wheels]

src/python/pants/backend/python/macros/python_requirements.py

@@ -1,6 +1,7 @@
 # Copyright 2014 Pants project contributors (see CONTRIBUTORS.md).
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 import os
+from itertools import groupby
 from pathlib import Path
 from typing import Iterable, Mapping, Optional
 
@@ -69,16 +70,20 @@ def __call__(
         requirements = parse_requirements_file(
             req_file.read_text(), rel_path=str(req_file.relative_to(get_buildroot()))
         )
-        for parsed_req in requirements:
+
+        grouped_requirements = groupby(requirements, lambda parsed_req: parsed_req.project_name)
+
+        for project_name, parsed_reqs_ in grouped_requirements:
+            parsed_reqs = list(parsed_reqs_)
             req_module_mapping = (
-                {parsed_req.project_name: module_mapping[parsed_req.project_name]}
-                if module_mapping and parsed_req.project_name in module_mapping
+                {project_name: module_mapping[project_name]}
+                if module_mapping and project_name in module_mapping
                 else None
             )
             self._parse_context.create_object(
                 "python_requirement_library",
-                name=parsed_req.project_name,
-                requirements=[parsed_req],
+                name=project_name,
+                requirements=parsed_reqs,
                 module_mapping=req_module_mapping,
                 dependencies=[requirements_dep],
             )

src/python/pants/backend/python/macros/python_requirements_test.py

@@ -40,12 +40,13 @@ def assert_python_requirements(
         Targets,
         [Specs(AddressSpecs([DescendantAddresses("")]), FilesystemSpecs([]))],
     )
+
     assert {expected_file_dep, *expected_targets} == set(targets)
 
 
 def test_requirements_txt(rule_runner: RuleRunner) -> None:
     """This tests that we correctly create a new python_requirement_library for each entry in a
-    requirements.txt file.
+    requirements.txt file, where each dependency is unique.
 
     Some edge cases:
     * We ignore comments and options (values that start with `--`).
@@ -104,6 +105,55 @@ def test_requirements_txt(rule_runner: RuleRunner) -> None:
     )
 
 
+def test_multiple_versions(rule_runner: RuleRunner) -> None:
+    """This tests that we correctly create a new python_requirement_library for each unique
+    dependency name in a requirements.txt file, grouping duplicated dependency names to handle
+    multiple requirement strings per PEP 508."""
+
+    assert_python_requirements(
+        rule_runner,
+        "python_requirements(module_mapping={'ansicolors': ['colors']})",
+        dedent(
+            """\
+            Django>=3.2
+            Django==3.2.7
+            confusedmonkey==86
+            repletewateringcan>=7
+            """
+        ),
+        expected_file_dep=PythonRequirementsFile(
+            {"sources": ["requirements.txt"]},
+            Address("", target_name="requirements.txt"),
+        ),
+        expected_targets=[
+            PythonRequirementLibrary(
+                {
+                    "dependencies": [":requirements.txt"],
+                    "requirements": [
+                        Requirement.parse("Django>=3.2"),
+                        Requirement.parse("Django==3.2.7"),
+                    ],
+                },
+                Address("", target_name="Django"),
+            ),
+            PythonRequirementLibrary(
+                {
+                    "dependencies": [":requirements.txt"],
+                    "requirements": [Requirement.parse("confusedmonkey==86")],
+                },
+                Address("", target_name="confusedmonkey"),
+            ),
+            PythonRequirementLibrary(
+                {
+                    "dependencies": [":requirements.txt"],
+                    "requirements": [Requirement.parse("repletewateringcan>=7")],
+                },
+                Address("", target_name="repletewateringcan"),
+            ),
+        ],
+    )
+
+
 def test_invalid_req(rule_runner: RuleRunner) -> None:
     """Test that we give a nice error message."""
     fake_file_tgt = PythonRequirementsFile({"sources": ["doesnt matter"]}, Address("doesnt_matter"))