Remove checks for missing root nodes.

docs/source/changes.md

@@ -26,6 +26,8 @@ releases are available on [PyPI](https://pypi.org/project/pytask) and
 - {pull}`477` updates the PyPI action.
 - {pull}`478` replaces black with ruff-format.
 - {pull}`479` gives skips a higher precedence as an outcome than ancestor failed.
+- {pull}`480` removes the check for missing root nodes from the generation of the DAG.
+  It is delegated to the check during the execution.
 
 ## 0.4.1 - 2023-10-11
 

docs/source/reference_guides/hookspecs.md

@@ -23,14 +23,12 @@ hooks are allowed to raise exceptions which are handled and stored in a report.
 
 ```{eval-rst}
 .. autofunction:: pytask_add_hooks
-
 ```
 
 ## Command Line Interface
 
 ```{eval-rst}
 .. autofunction:: pytask_extend_command_line_interface
-
 ```
 
 ## Configuration
@@ -41,20 +39,9 @@ together.
 
 ```{eval-rst}
 .. autofunction:: pytask_configure
-```
-
-```{eval-rst}
 .. autofunction:: pytask_parse_config
-```
-
-```{eval-rst}
 .. autofunction:: pytask_post_parse
-
-```
-
-```{eval-rst}
 .. autofunction:: pytask_unconfigure
-
 ```
 
 ## Collection
@@ -63,47 +50,16 @@ The following hooks traverse directories and collect tasks from files.
 
 ```{eval-rst}
 .. autofunction:: pytask_collect
-```
-
-```{eval-rst}
 .. autofunction:: pytask_ignore_collect
-```
-
-```{eval-rst}
 .. autofunction:: pytask_collect_modify_tasks
-```
-
-```{eval-rst}
 .. autofunction:: pytask_collect_file_protocol
-```
-
-```{eval-rst}
 .. autofunction:: pytask_collect_file
-```
-
-```{eval-rst}
 .. autofunction:: pytask_collect_task_protocol
-```
-
-```{eval-rst}
 .. autofunction:: pytask_collect_task_setup
-```
-
-```{eval-rst}
 .. autofunction:: pytask_collect_task
-```
-
-```{eval-rst}
 .. autofunction:: pytask_collect_task_teardown
-```
-
-```{eval-rst}
 .. autofunction:: pytask_collect_node
-```
-
-```{eval-rst}
 .. autofunction:: pytask_collect_log
-
 ```
 
 ## Resolving Dependencies
@@ -120,21 +76,8 @@ your plugin.
 
 ```{eval-rst}
 .. autofunction:: pytask_dag
-```
-
-```{eval-rst}
 .. autofunction:: pytask_dag_create_dag
-```
-
-```{eval-rst}
-.. autofunction:: pytask_dag_validate_dag
-```
-
-```{eval-rst}
 .. autofunction:: pytask_dag_select_execution_dag
-```
-
-```{eval-rst}
 .. autofunction:: pytask_dag_log
 
 ```
@@ -145,48 +88,15 @@ The following hooks execute the tasks and log information on the result in the t
 
 ```{eval-rst}
 .. autofunction:: pytask_execute
-```
-
-```{eval-rst}
 .. autofunction:: pytask_execute_log_start
-```
-
-```{eval-rst}
 .. autofunction:: pytask_execute_create_scheduler
-```
-
-```{eval-rst}
 .. autofunction:: pytask_execute_build
-```
-
-```{eval-rst}
 .. autofunction:: pytask_execute_task_protocol
-```
-
-```{eval-rst}
 .. autofunction:: pytask_execute_task_log_start
-```
-
-```{eval-rst}
 .. autofunction:: pytask_execute_task_setup
-```
-
-```{eval-rst}
 .. autofunction:: pytask_execute_task
-```
-
-```{eval-rst}
 .. autofunction:: pytask_execute_task_teardown
-```
-
-```{eval-rst}
 .. autofunction:: pytask_execute_task_process_report
-```
-
-```{eval-rst}
 .. autofunction:: pytask_execute_task_log_end
-```
-
-```{eval-rst}
 .. autofunction:: pytask_execute_log_end
 ```

src/_pytask/dag.py

@@ -3,12 +3,10 @@
 
 import itertools
 import sys
-from typing import Sequence
 from typing import TYPE_CHECKING
 
 import networkx as nx
 from _pytask.config import hookimpl
-from _pytask.config import IS_FILE_SYSTEM_CASE_SENSITIVE
 from _pytask.console import ARROW_DOWN_ICON
 from _pytask.console import console
 from _pytask.console import FILE_ICON
@@ -23,8 +21,6 @@
 from _pytask.database_utils import State
 from _pytask.exceptions import ResolvingDependenciesError
 from _pytask.mark import Mark
-from _pytask.mark_utils import get_marks
-from _pytask.mark_utils import has_mark
 from _pytask.node_protocols import PNode
 from _pytask.node_protocols import PTask
 from _pytask.nodes import PythonNode
@@ -48,13 +44,12 @@ def pytask_dag(session: Session) -> bool | None:
             session=session, tasks=session.tasks
         )
         session.hook.pytask_dag_modify_dag(session=session, dag=session.dag)
-        session.hook.pytask_dag_validate_dag(session=session, dag=session.dag)
         session.hook.pytask_dag_select_execution_dag(session=session, dag=session.dag)
 
     except Exception:  # noqa: BLE001
         report = DagReport.from_exception(sys.exc_info())
         session.hook.pytask_dag_log(session=session, report=report)
-        session.dag_reports = report
+        session.dag_report = report
 
         raise ResolvingDependenciesError from None
 
@@ -63,7 +58,7 @@ def pytask_dag(session: Session) -> bool | None:
 
 
 @hookimpl
-def pytask_dag_create_dag(tasks: list[PTask]) -> nx.DiGraph:
+def pytask_dag_create_dag(session: Session, tasks: list[PTask]) -> nx.DiGraph:
     """Create the DAG from tasks, dependencies and products."""
 
     def _add_dependency(dag: nx.DiGraph, task: PTask, node: PNode) -> None:
@@ -101,6 +96,7 @@ def _add_product(dag: nx.DiGraph, task: PTask, node: PNode) -> None:
         )
 
     _check_if_dag_has_cycles(dag)
+    _check_if_tasks_have_the_same_products(dag, session.config["paths"])
 
     return dag
 
@@ -123,13 +119,6 @@ def pytask_dag_select_execution_dag(session: Session, dag: nx.DiGraph) -> None:
                 )
 
 
-@hookimpl
-def pytask_dag_validate_dag(session: Session, dag: nx.DiGraph) -> None:
-    """Validate the DAG."""
-    _check_if_root_nodes_are_available(dag, session.config["paths"])
-    _check_if_tasks_have_the_same_products(dag, session.config["paths"])
-
-
 def _have_task_or_neighbors_changed(
     session: Session, dag: nx.DiGraph, task: PTask
 ) -> bool:
@@ -198,98 +187,6 @@ def _format_cycles(dag: nx.DiGraph, cycles: list[tuple[str, ...]]) -> str:
     return "\n".join(lines[:-1])
 
 
-_TEMPLATE_ERROR: str = (
-    "Some dependencies do not exist or are not produced by any task. See the following "
-    "tree which shows which dependencies are missing for which tasks.\n\n{}"
-)
-if IS_FILE_SYSTEM_CASE_SENSITIVE:
-    _TEMPLATE_ERROR += (
-        "\n\n(Hint: Your file-system is case-sensitive. Check the paths' "
-        "capitalization carefully.)"
-    )
-
-
-def _check_if_root_nodes_are_available(dag: nx.DiGraph, paths: Sequence[Path]) -> None:
-    __tracebackhide__ = True
-
-    missing_root_nodes = []
-    is_task_skipped: dict[str, bool] = {}
-
-    for node in dag.nodes:
-        is_node = "node" in dag.nodes[node]
-        is_without_parents = len(list(dag.predecessors(node))) == 0
-        if is_node and is_without_parents:
-            are_all_tasks_skipped, is_task_skipped = _check_if_tasks_are_skipped(
-                node, dag, is_task_skipped
-            )
-            if not are_all_tasks_skipped:
-                try:
-                    node_exists = dag.nodes[node]["node"].state()
-                except Exception as e:  # noqa: BLE001
-                    msg = _format_exception_from_failed_node_state(node, dag, paths)
-                    raise ResolvingDependenciesError(msg) from e
-                if not node_exists:
-                    missing_root_nodes.append(node)
-
-    if missing_root_nodes:
-        dictionary = {}
-        for node in missing_root_nodes:
-            short_node_name = format_node_name(dag.nodes[node]["node"], paths).plain
-            not_skipped_successors = [
-                task for task in dag.successors(node) if not is_task_skipped[task]
-            ]
-            short_successors = reduce_names_of_multiple_nodes(
-                not_skipped_successors, dag, paths
-            )
-            dictionary[short_node_name] = short_successors
-
-        text = _format_dictionary_to_tree(dictionary, "Missing dependencies:")
-        raise ResolvingDependenciesError(_TEMPLATE_ERROR.format(text)) from None
-
-
-def _format_exception_from_failed_node_state(
-    node_signature: str, dag: nx.DiGraph, paths: Sequence[Path]
-) -> str:
-    """Format message when ``node.state()`` threw an exception."""
-    tasks = [dag.nodes[i]["task"] for i in dag.successors(node_signature)]
-    names = [task.name for task in tasks]
-    successors = ", ".join([f"{name!r}" for name in names])
-    node_name = format_node_name(dag.nodes[node_signature]["node"], paths).plain
-    return (
-        f"While checking whether dependency {node_name!r} from task(s) "
-        f"{successors} exists, an error was raised."
-    )
-
-
-def _check_if_tasks_are_skipped(
-    node: PNode, dag: nx.DiGraph, is_task_skipped: dict[str, bool]
-) -> tuple[bool, dict[str, bool]]:
-    """Check for a given node whether it is only used by skipped tasks."""
-    are_all_tasks_skipped = []
-    for successor in dag.successors(node):
-        if successor not in is_task_skipped:
-            is_task_skipped[successor] = _check_if_task_is_skipped(successor, dag)
-        are_all_tasks_skipped.append(is_task_skipped[successor])
-
-    return all(are_all_tasks_skipped), is_task_skipped
-
-
-def _check_if_task_is_skipped(task_name: str, dag: nx.DiGraph) -> bool:
-    task = dag.nodes[task_name]["task"]
-    is_skipped = has_mark(task, "skip")
-
-    if is_skipped:
-        return True
-
-    skip_if_markers = get_marks(task, "skipif")
-    return any(_skipif(*marker.args, **marker.kwargs)[0] for marker in skip_if_markers)
-
-
-def _skipif(condition: bool, *, reason: str) -> tuple[bool, str]:
-    """Shameless copy to circumvent circular imports."""
-    return condition, reason
-
-
 def _format_dictionary_to_tree(dict_: dict[str, list[str]], title: str) -> str:
     """Format missing root nodes."""
     tree = Tree(title)

src/_pytask/dag_command.py

@@ -5,7 +5,6 @@
 import sys
 from pathlib import Path
 from typing import Any
-from typing import TYPE_CHECKING
 
 import click
 import networkx as nx
@@ -31,10 +30,6 @@
 from rich.traceback import Traceback
 
 
-if TYPE_CHECKING:
-    from typing import NoReturn
-
-
 class _RankDirection(enum.Enum):
     TB = "TB"
     LR = "LR"
@@ -82,7 +77,7 @@ def pytask_extend_command_line_interface(cli: click.Group) -> None:
     help=_HELP_TEXT_RANK_DIRECTION,
     default=_RankDirection.TB,
 )
-def dag(**raw_config: Any) -> NoReturn:
+def dag(**raw_config: Any) -> int:
     """Create a visualization of the project's directed acyclic graph."""
     try:
         pm = get_plugin_manager()

src/_pytask/execute.py

@@ -8,6 +8,7 @@
 from typing import TYPE_CHECKING
 
 from _pytask.config import hookimpl
+from _pytask.config import IS_FILE_SYSTEM_CASE_SENSITIVE
 from _pytask.console import console
 from _pytask.console import create_summary_panel
 from _pytask.console import create_url_style_for_task
@@ -36,6 +37,7 @@
 from _pytask.tree_util import tree_structure
 from rich.text import Text
 
+
 if TYPE_CHECKING:
     from _pytask.session import Session
 
@@ -125,7 +127,12 @@ def pytask_execute_task_setup(session: Session, task: PTask) -> None:
     for dependency in session.dag.predecessors(task.signature):
         node = session.dag.nodes[dependency]["node"]
         if not node.state():
-            msg = f"{node.name} is missing and required for {task.name}."
+            msg = f"{task.name} requires missing node {node.name}."
+            if IS_FILE_SYSTEM_CASE_SENSITIVE:
+                msg += (
+                    "\n\n(Hint: Your file-system is case-sensitive. Check the paths' "
+                    "capitalization carefully.)"
+                )
             raise NodeNotFoundError(msg)
 
     # Create directory for product if it does not exist. Maybe this should be a `setup`