Take a common ancestor if closest not available to shorten paths.

docs/changes.rst

@@ -7,6 +7,13 @@ all releases are available on `PyPI <https://pypi.org/project/pytask>`_ and
 `Anaconda.org <https://anaconda.org/conda-forge/pytask>`_.
 
 
+0.0.14 - 2021-xx-xx
+-------------------
+
+- :gh:`76` fixes :gh:`75` which reports a bug when a closest ancestor cannot be found to
+  shorten node names in the CLI output. Instead a common ancestor is used.
+
+
 0.0.13 - 2021-03-09
 -------------------
 

src/_pytask/nodes.py

@@ -17,6 +17,9 @@
 from _pytask.exceptions import NodeNotCollectedError
 from _pytask.exceptions import NodeNotFoundError
 from _pytask.mark import get_marks_from_obj
+from _pytask.path import find_closest_ancestor
+from _pytask.path import find_common_ancestor
+from _pytask.path import relative_to
 from _pytask.shared import find_duplicates
 
 
@@ -337,66 +340,6 @@ def _create_task_name(path: Path, base_name: str):
     return path.as_posix() + "::" + base_name
 
 
-def _relative_to(path: Path, source: Path, include_source: bool = True):
-    """Make a path relative to another path.
-
-    In contrast to :meth:`pathlib.Path.relative_to`, this function allows to keep the
-    name of the source path.
-
-    Examples
-    --------
-    >>> from pathlib import Path
-    >>> _relative_to(Path("folder", "file.py"), Path("folder")).as_posix()
-    'folder/file.py'
-    >>> _relative_to(Path("folder", "file.py"), Path("folder"), False).as_posix()
-    'file.py'
-
-    """
-    return Path(source.name if include_source else "", path.relative_to(source))
-
-
-def _find_closest_ancestor(path: Path, potential_ancestors: List[Path]):
-    """Find the closest ancestor of a path.
-
-    In case a path is the path to the task file itself, we return the path.
-
-    .. note::
-
-        The check :meth:`pathlib.Path.is_file` only succeeds when the file exists. This
-        must be true as otherwise an error is raised by :obj:`click` while using the
-        cli.
-
-    Examples
-    --------
-    >>> from pathlib import Path
-    >>> _find_closest_ancestor(Path("folder", "file.py"), [Path("folder")]).as_posix()
-    'folder'
-
-    >>> paths = [Path("folder"), Path("folder", "subfolder")]
-    >>> _find_closest_ancestor(Path("folder", "subfolder", "file.py"), paths).as_posix()
-    'folder/subfolder'
-
-    """
-    closest_ancestor = None
-    for ancestor in potential_ancestors:
-        if ancestor == path:
-            closest_ancestor = path
-            break
-
-        # Paths can also point to files in which case we want to take the parent folder.
-        if ancestor.is_file():
-            ancestor = ancestor.parent
-
-        if ancestor in path.parents:
-            if closest_ancestor is None or (
-                len(path.relative_to(ancestor).parts)
-                < len(path.relative_to(closest_ancestor).parts)
-            ):
-                closest_ancestor = ancestor
-
-    return closest_ancestor
-
-
 def reduce_node_name(node, paths: List[Path]):
     """Reduce the node name.
 
@@ -407,17 +350,21 @@ def reduce_node_name(node, paths: List[Path]):
     path from one path in ``session.config["paths"]`` to the node.
 
     """
-    ancestor = _find_closest_ancestor(node.path, paths)
+    ancestor = find_closest_ancestor(node.path, paths)
     if ancestor is None:
-        raise ValueError("A node must be defined in a child of 'paths'.")
-    elif isinstance(node, MetaTask):
+        try:
+            ancestor = find_common_ancestor(node.path, *paths)
+        except ValueError:
+            ancestor = node.path.parents[-1]
+
+    if isinstance(node, MetaTask):
         if ancestor == node.path:
             name = _create_task_name(Path(node.path.name), node.base_name)
         else:
-            shortened_path = _relative_to(node.path, ancestor)
+            shortened_path = relative_to(node.path, ancestor)
             name = _create_task_name(shortened_path, node.base_name)
     elif isinstance(node, MetaNode):
-        name = _relative_to(node.path, ancestor).as_posix()
+        name = relative_to(node.path, ancestor).as_posix()
     else:
         raise ValueError(f"Unknown node {node} with type '{type(node)}'.")
 

src/_pytask/path.py

@@ -0,0 +1,96 @@
+"""This module contains code to handle paths."""
+from pathlib import Path
+from pathlib import PurePath
+from typing import List
+from typing import Union
+
+
+def relative_to(
+    path: Union[str, Path], source: Union[str, Path], include_source: bool = True
+) -> Union[str, Path]:
+    """Make a path relative to another path.
+
+    In contrast to :meth:`pathlib.Path.relative_to`, this function allows to keep the
+    name of the source path.
+
+    Examples
+    --------
+    The default behavior of :mod:`pathlib` is to exclude the source path from the
+    relative path.
+
+    >>> relative_to("folder/file.py", "folder", False).as_posix()
+    'file.py'
+
+    To provide relative locations to users, it is sometimes more helpful to provide the
+    source as an orientation.
+
+    >>> relative_to("folder/file.py", "folder").as_posix()
+    'folder/file.py'
+
+    """
+    source_name = Path(source).name if include_source else ""
+    return Path(source_name, Path(path).relative_to(source))
+
+
+def find_closest_ancestor(
+    path: Union[str, Path], potential_ancestors: List[Union[str, Path]]
+) -> Path:
+    """Find the closest ancestor of a path.
+
+    In case a path is the path to the task file itself, we return the path.
+
+    .. note::
+
+        The check :meth:`pathlib.Path.is_file` only succeeds when the file exists. This
+        must be true as otherwise an error is raised by :obj:`click` while using the
+        cli.
+
+    Examples
+    --------
+    >>> from pathlib import Path
+    >>> find_closest_ancestor(Path("folder", "file.py"), [Path("folder")]).as_posix()
+    'folder'
+
+    >>> paths = [Path("folder"), Path("folder", "subfolder")]
+    >>> find_closest_ancestor(Path("folder", "subfolder", "file.py"), paths).as_posix()
+    'folder/subfolder'
+
+    """
+    closest_ancestor = None
+    for ancestor in potential_ancestors:
+        if ancestor == path:
+            closest_ancestor = path
+            break
+
+        # Paths can also point to files in which case we want to take the parent folder.
+        if ancestor.is_file():
+            ancestor = ancestor.parent
+
+        if ancestor in path.parents:
+            if closest_ancestor is None or (
+                len(path.relative_to(ancestor).parts)
+                < len(path.relative_to(closest_ancestor).parts)
+            ):
+                closest_ancestor = ancestor
+
+    return closest_ancestor
+
+
+def find_common_ancestor(*paths: Union[str, Path]) -> Path:
+    """Find a common ancestor of many paths."""
+    paths = [path if isinstance(path, PurePath) else Path(path) for path in paths]
+
+    for path in paths:
+        if not path.is_absolute():
+            raise ValueError(
+                f"Cannot find common ancestor for relative paths. {path} is relative."
+            )
+
+    common_parents = set.intersection(*[set(path.parents) for path in paths])
+
+    if len(common_parents) == 0:
+        raise ValueError("Paths have no common ancestor.")
+    else:
+        longest_parent = sorted(common_parents, key=lambda x: len(x.parts))[-1]
+
+    return longest_parent

tests/test_capture.py

@@ -218,7 +218,7 @@ def task_unicode():
 
 
 @pytest.mark.end_to_end
-@pytest.mark.xfail(reason="pytask cannot capture during collection.")
+@pytest.mark.xfail(strict=True, reason="pytask cannot capture during collection.")
 def test_collect_capturing(tmp_path, runner):
     source = """
     import sys

tests/test_nodes.py

@@ -10,8 +10,6 @@
 from _pytask.nodes import _convert_objects_to_node_dictionary
 from _pytask.nodes import _create_task_name
 from _pytask.nodes import _extract_nodes_from_function_markers
-from _pytask.nodes import _find_closest_ancestor
-from _pytask.nodes import _relative_to
 from _pytask.nodes import depends_on
 from _pytask.nodes import FilePathNode
 from _pytask.nodes import MetaNode
@@ -203,37 +201,6 @@ def test_create_task_name(path, name, expected):
     assert result == expected
 
 
-@pytest.mark.unit
-@pytest.mark.parametrize(
-    "path, source, include_source, expected",
-    [
-        (Path("src/hello.py"), Path("src"), True, Path("src/hello.py")),
-        (Path("src/hello.py"), Path("src"), False, Path("hello.py")),
-    ],
-)
-def test_relative_to(path, source, include_source, expected):
-    result = _relative_to(path, source, include_source)
-    assert result == expected
-
-
-@pytest.mark.unit
-@pytest.mark.parametrize(
-    "path, potential_ancestors, expected",
-    [
-        (Path("src/task.py"), [Path("src"), Path("bld")], Path("src")),
-        (Path("tasks/task.py"), [Path("src"), Path("bld")], None),
-        (Path("src/ts/task.py"), [Path("src"), Path("src/ts")], Path("src/ts")),
-        (Path("src/in.txt"), [Path("src/task_d.py")], Path("src")),
-        (Path("src/task.py"), [Path("src/task.py")], Path("src/task.py")),
-    ],
-)
-def test_find_closest_ancestor(monkeypatch, path, potential_ancestors, expected):
-    # Ensures that files are detected by an existing suffix not if they also exist.
-    monkeypatch.setattr("_pytask.nodes.pathlib.Path.is_file", lambda x: bool(x.suffix))
-    result = _find_closest_ancestor(path, potential_ancestors)
-    assert result == expected
-
-
 @attr.s
 class DummyTask(MetaTask):
     path = attr.ib()
@@ -259,19 +226,21 @@ class FalseNode:
 @pytest.mark.parametrize(
     "node, paths, expectation, expected",
     [
-        (
+        pytest.param(
             FilePathNode.from_path(_ROOT.joinpath("src/module.py")),
             [_ROOT.joinpath("alternative_src")],
-            pytest.raises(ValueError, match="A node must be"),
-            None,
+            does_not_raise(),
+            "pytask/src/module.py",
+            id="Common path found for FilePathNode not in 'paths' and 'paths'",
         ),
-        (
+        pytest.param(
             FalseNode(_ROOT.joinpath("src/module.py")),
             [_ROOT.joinpath("src")],
             pytest.raises(ValueError, match="Unknown node"),
             None,
+            id="throw error on unknown node type.",
         ),
-        (
+        pytest.param(
             DummyTask(
                 _ROOT.joinpath("top/src/module.py"),
                 _ROOT.joinpath("top/src/module.py").as_posix() + "::task_func",
@@ -280,14 +249,16 @@ class FalseNode:
             [_ROOT.joinpath("top/src")],
             does_not_raise(),
             "src/module.py::task_func",
+            id="make task name relative to 'paths'.",
         ),
-        (
+        pytest.param(
             FilePathNode.from_path(_ROOT.joinpath("top/src/module.py")),
             [_ROOT.joinpath("top/src")],
             does_not_raise(),
             "src/module.py",
+            id="make filepathnode relative to 'paths'.",
         ),
-        (
+        pytest.param(
             PythonFunctionTask(
                 "task_d",
                 _ROOT.joinpath("top/src/module.py").as_posix() + "::task_d",
@@ -297,6 +268,7 @@ class FalseNode:
             [_ROOT.joinpath("top/src/module.py")],
             does_not_raise(),
             "module.py::task_d",
+            id="shorten task name when task module is passed to 'paths'.",
         ),
     ],
 )

tests/test_parametrize.py

@@ -44,7 +44,7 @@ def func(i):
 
 
 @pytest.mark.integration
-@pytest.mark.xfail(reason="Cartesian task product is disabled.")
+@pytest.mark.xfail(strict=True, reason="Cartesian task product is disabled.")
 def test_pytask_generate_tasks_1(session):
     @pytask.mark.parametrize("j", range(2))
     @pytask.mark.parametrize("i", range(2))
@@ -62,7 +62,7 @@ def func(i, j):
 
 
 @pytest.mark.integration
-@pytest.mark.xfail(reason="Cartesian task product is disabled.")
+@pytest.mark.xfail(strict=True, reason="Cartesian task product is disabled.")
 def test_pytask_generate_tasks_2(session):
     @pytask.mark.parametrize("j, k", itertools.product(range(2), range(2)))
     @pytask.mark.parametrize("i", range(2))
@@ -264,7 +264,7 @@ def task_func(i):
 
 
 @pytest.mark.end_to_end
-@pytest.mark.xfail(reason="Cartesian task product is disabled.")
+@pytest.mark.xfail(strict=True, reason="Cartesian task product is disabled.")
 def test_two_parametrize_w_ids(tmp_path):
     tmp_path.joinpath("task_dummy.py").write_text(
         textwrap.dedent(