dulwich: use untracked_files="no" in is_dirty

This will speed up calling `is_dirty` with untracked_files=False

related to #69

Author: dtrifiro

scmrepo/git/backend/dulwich/__init__.py

@@ -344,8 +344,12 @@ def is_tracked(self, path: str) -> bool:
         return False
 
     def is_dirty(self, untracked_files: bool = False) -> bool:
-        staged, unstaged, untracked = self.status()
-        return bool(staged or unstaged or (untracked_files and untracked))
+        if untracked_files:
+            staged, unstaged, untracked = self.status()
+            return bool(staged or unstaged or untracked)
+
+        staged, unstaged, _ = self.status(untracked_files="no")
+        return bool(staged or unstaged)
 
     def active_branch(self) -> str:
         raise NotImplementedError

tests/test_git.py

@@ -1041,3 +1041,50 @@ def test_status(
     assert staged["modify"] == ["foo"]
     assert unstaged == ["bar"]
     assert untracked == expected_untracked
+
+
+@pytest.mark.skip_git_backend("pygit2")
+@pytest.mark.parametrize("untracked_files", [False, True])
+def test_is_dirty(
+    tmp_dir: TmpDir,
+    scm: Git,
+    git: Git,
+    tmp_dir_factory: TempDirFactory,
+    mocker,
+    untracked_files: str,
+):
+    tmp_dir.gen(
+        {
+            "foo": "foo",
+        }
+    )
+    scm.add_commit(["foo"], message="init")
+
+    assert not git.is_dirty()
+
+    with (tmp_dir / "foo").open("a") as fobj:
+        fobj.write("modified")
+
+    assert git.is_dirty(untracked_files)
+    scm.add_commit(["foo"], message="commit")
+
+    with (tmp_dir / "untracked").open("w") as fobj:
+        fobj.write("untracked")
+
+    backend = list(git.backends)[0]
+    assert backend in ("dulwich", "gitpython")
+    if backend == "dulwich":
+        spy = mocker.spy(git.dulwich, "status")
+    elif backend == "gitpython":
+        spy = mocker.spy(git.gitpython.repo, "is_dirty")
+
+    assert git.is_dirty(untracked_files) == untracked_files
+    assert spy.called
+    args, kwargs = spy.call_args
+    if backend == "dulwich":
+        if untracked_files:
+            assert not kwargs
+        else:
+            assert kwargs["untracked_files"] == "no"
+    elif backend == "gitpython":
+        assert kwargs["untracked_files"] == untracked_files