Add option --do-not-add to sync-hooks-additional-dependencies

Closes #8

README.md

@@ -47,7 +47,8 @@ repos:
         # "mypy" is the id of a pre-commit hook
         # "types" is the name of your poetry group containing typing dependencies
         # "main" is the automated name associated with the "default" poetry dependencies
-        args: ["--bind", "mypy=types,main"]
+        # `--do-not-add` will update or remove dependencies, but not add any new one.
+        args: ["--bind", "mypy=types,main", "--do-not-add"]
 ```
 
 ## How it works
@@ -76,6 +77,11 @@ look for the version of all the dependencies of these groups in your
 `poetry.lock`. In `.pre-commit-config.yaml`, it will identify the corresponding
 hook, and set the `additional_dependencies` key to the list sorted of all the
 dependencies.
+If you pass the option `--do-not-add`, packages that are already in your pre-commit
+config file will be updated or removed (if they are not listed in any of the considered
+poetry dependencies' groups), but no new packages will be added. You should use
+this to avoid installing unecessary dependencies in the pre-commit environment,
+e.g. if mypy does not need all of them to type check your project.
 
 ## Credit where it's due
 

poetry_to_pre_commit/sync_hooks_additional_dependencies.py

@@ -2,6 +2,7 @@
 
 import argparse
 import pathlib
+import re
 import sys
 from typing import Any, Iterable
 
@@ -46,6 +47,11 @@ def get_sync_hooks_additional_dependencies_parser() -> argparse.ArgumentParser:
         f"`--bind mypy={MAIN_GROUP} --bind mypy:types` or "
         f"`--bind mypy={MAIN_GROUP},types`).",
     )
+    parser.add_argument(
+        "--do-not-add",
+        action="store_true",
+        help="Update or remove dependencies, but don't add any new one.",
+    )
     return parser
 
 
@@ -68,12 +74,39 @@ def get_poetry_deps(*, cwd: pathlib.Path | None = None, group: str) -> Iterable[
         yield f"{dep.complete_name}=={package.version}"
 
 
+def update_or_remove_additional_deps(
+    poetry_deps: set[str], hook_additional_deps: list[str]
+) -> set[str]:
+    # Additional packages that are already in pre-commit configuration could be listed with
+    # any format that is accepted by pip. The following regex might not cover all the cases.
+    current_deps = re.findall(
+        r"^\s*([^=><\[\s]+)", "\n".join(hook_additional_deps), re.MULTILINE
+    )
+
+    return {
+        package
+        for package in poetry_deps
+        # package is yielded by `get_poetry_deps` above, and we are pretty sure that this won't raise `IndexError`
+        if package.split("==")[0].split("[")[0] in current_deps
+    }
+
+
 def sync_hook_additional_deps(
     *,
     config: dict[str, Any],
     deps_by_group: dict[str, list[str]],
     bind: dict[str, set[str]],
+    do_not_add: bool = False,
 ) -> None:
+    """Sync additional dependencies from `deps_by_group` to `config`.
+
+    Args:
+        config: pre-commit config
+        deps_by_group: packages from poetry.lock, by poetry dependency group
+        bind: poetry dependency groups to consider for each pre-commit hook
+        do_not_add: Update or remove existing dependencies from the "additional_dependencies"
+            section of pre-commit config, but do not add new dependencies from poetry.
+    """
     for repo in config.get("repos", []):
         for hook in repo.get("hooks", []):
             hook_id = hook["id"]
@@ -86,14 +119,19 @@ def sync_hook_additional_deps(
             for group in groups:
                 deps.update(deps_by_group.get(group, set()))
 
-            hook["additional_dependencies"] = sorted(deps)
+            hook["additional_dependencies"] = sorted(
+                update_or_remove_additional_deps(deps, hook["additional_dependencies"])
+                if do_not_add
+                else deps
+            )
 
 
 def sync_hooks_additional_dependencies(
     argv: list[str],
     pre_commit_path: pathlib.Path = PRE_COMMIT_CONFIG_FILE,
     poetry_cwd: pathlib.Path | None = None,
-):
+) -> None:
+    """Sync additional dependencies with the packages versions from poetry lock file."""
     parser = get_sync_hooks_additional_dependencies_parser()
     args = parser.parse_args(argv)
 
@@ -105,8 +143,14 @@ def sync_hooks_additional_dependencies(
             deps_by_group[group] = set(get_poetry_deps(cwd=poetry_cwd, group=group))
 
     with common.pre_commit_config_roundtrip(pre_commit_path) as config:
-        sync_hook_additional_deps(config=config, bind=bind, deps_by_group=deps_by_group)
+        sync_hook_additional_deps(
+            config=config,
+            bind=bind,
+            deps_by_group=deps_by_group,
+            do_not_add=args.do_not_add,
+        )
 
 
-def sync_hooks_additional_dependencies_cli():
+def sync_hooks_additional_dependencies_cli() -> None:
+    """Entrypoint when running from the shell."""
     sync_hooks_additional_dependencies(argv=sys.argv[1:])

tests/test_sync_hooks_additional_dependencies.py

@@ -121,3 +121,90 @@ def test_sync_hooks_additional_dependencies(tmp_path, poetry_cwd):
         "psycopg[pool]==3.1.18",
         "types-requests==2.31.0.20240311",
     ]
+
+
+class TestParamDoNotAdd:
+    """Test the option `--do-not-add`."""
+
+    @pytest.mark.parametrize(
+        ("poetry_deps", "additional_deps", "expected_additional_deps"),
+        [
+            (["a==1", "b"], ["a"], ["a==1"]),
+            (["a==1", "b"], ["a[x]==2"], ["a==1"]),
+            (["a[x]==1", "b"], ["a"], ["a[x]==1"]),
+            (["a[x]==1", "b"], ["a[x]"], ["a[x]==1"]),
+            (["a==1", "b"], ["a == 2"], ["a==1"]),
+            (["a==1", "b"], ["a<=2"], ["a==1"]),
+            (["a==1", "b"], ["a>=1"], ["a==1"]),
+        ],
+    )
+    def test_sync_hook_additional_deps(
+        self, poetry_deps, additional_deps, expected_additional_deps
+    ) -> None:
+        """Check that `sync_hook_additional_deps` handles the different ways to write a package entry."""
+        config = {
+            "repos": [
+                {"hooks": [{"id": "mypy", "additional_dependencies": additional_deps}]}
+            ]
+        }
+        deps_by_group = {"main": poetry_deps}
+        bind = {"mypy": {"main"}}
+
+        sync_hooks_additional_dependencies.sync_hook_additional_deps(
+            config=config, deps_by_group=deps_by_group, bind=bind, do_not_add=True
+        )
+        assert config == {
+            "repos": [
+                {
+                    "hooks": [
+                        {
+                            "id": "mypy",
+                            "additional_dependencies": expected_additional_deps,
+                        }
+                    ]
+                }
+            ]
+        }
+
+    @pytest.mark.parametrize(
+        ("additional_deps", "expected_additional_deps"),
+        [
+            ([], []),
+            (["attrs", "psycopg"], ["attrs==23.2.0", "psycopg[pool]==3.1.18"]),
+            (["attrs", "psycopg[pool]"], ["attrs==23.2.0", "psycopg[pool]==3.1.18"]),
+            (["attrs", "psycopg[dummy]"], ["attrs==23.2.0", "psycopg[pool]==3.1.18"]),
+            (["attrs", "fastapi==1.0.0"], ["attrs==23.2.0"]),
+        ],
+    )
+    def test_sync_hooks_additional_dependencies(
+        self, tmp_path, poetry_cwd, additional_deps, expected_additional_deps
+    ) -> None:
+        pre_commit_path = tmp_path / ".pre-commit-config.yaml"
+        ruamel.yaml.YAML().dump(
+            {
+                "repos": [
+                    {
+                        "repo": "https://github.com/foo/pyright-python",
+                        "rev": "v1.1.300",
+                        "hooks": [
+                            {
+                                "id": "pyright",
+                                "additional_dependencies": additional_deps,
+                            }
+                        ],
+                    }
+                ]
+            },
+            pre_commit_path,
+        )
+
+        sync_hooks_additional_dependencies.sync_hooks_additional_dependencies(
+            argv=["foo", "--bind", "pyright=types,main", "--do-not-add"],
+            pre_commit_path=pre_commit_path,
+            poetry_cwd=poetry_cwd,
+        )
+        result = ruamel.yaml.YAML().load(pre_commit_path.read_text())
+        assert (
+            result["repos"][0]["hooks"][0]["additional_dependencies"]
+            == expected_additional_deps
+        )