Path completion in python code (#4457)

* completions: path: Fix completing a single-arg python code segment

* tests: completions: path: Test completing python code

* news: Add path-completion-in-python-code

news/path-completion-in-python-code.rst

@@ -0,0 +1,23 @@
+**Added:**
+
+* <news item>
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* Completing a single-arg python code segment (e.g. ``@(/etc/hos<TAB>)``).
+
+**Security:**
+
+* <news item>

tests/test_path_completers.py

@@ -71,3 +71,18 @@ def test_path_from_partial_string(prefix):
     else:
         expected = (f"{quote}{string}{quote}", string, f"{prefix}{quote}", quote)
     assert out == expected
+
+
+@pytest.mark.parametrize("num_args", (0, 1, 2, 3))
+def test_path_in_python_code(num_args, completion_context_parse):
+    with tempfile.NamedTemporaryFile(prefix="long_name") as tmp:
+        args = []
+        if num_args:
+            args = ["blah"] * 3 + [tmp.name[:-2]]
+            args = args[-num_args:]
+
+        inner_line = " ".join(map(repr, args))
+        exp = xcp.complete_path(completion_context_parse(inner_line, len(inner_line)))
+        line = "@(" + inner_line
+        out = xcp.complete_path(completion_context_parse(line, len(line)))
+        assert out == exp

xonsh/completers/path.py

@@ -362,7 +362,7 @@ def complete_path(context):
     elif context.python:
         line = context.python.prefix
         # simple prefix _complete_path_raw will handle gracefully:
-        prefix = line.rsplit(" ", 1)[1]
+        prefix = line.rsplit(" ", 1)[-1]
         return _complete_path_raw(prefix, line, len(line) - len(prefix), len(line), {})
     return set(), 0