feat(13617): record reason for deselection and allow it to be displayed

src/_pytest/main.py

@@ -446,6 +446,9 @@ def pytest_collection_modifyitems(items: list[nodes.Item], config: Config) -> No
     deselected = []
     for colitem in items:
         if colitem.nodeid.startswith(deselect_prefixes):
+            colitem._deselected_reason = (
+                f"Deselected by --deselect option: {colitem.nodeid}"
+            )
             deselected.append(colitem)
         else:
             remaining.append(colitem)

src/_pytest/mark/__init__.py

@@ -217,6 +217,9 @@ def deselect_by_keyword(items: list[Item], config: Config) -> None:
     deselected = []
     for colitem in items:
         if not expr.evaluate(KeywordMatcher.from_item(colitem)):
+            colitem._deselected_reason = (
+                f"Keyword expression '{keywordexpr}' did not match."
+            )
             deselected.append(colitem)
         else:
             remaining.append(colitem)
@@ -266,9 +269,9 @@ def deselect_by_mark(items: list[Item], config: Config) -> None:
         if expr.evaluate(MarkMatcher.from_markers(item.iter_markers())):
             remaining.append(item)
         else:
+            item._deselected_reason = f"Mark expression '{matchexpr}' did not match."
             deselected.append(item)
     if deselected:
-        config.hook.pytest_deselected(items=deselected)
         items[:] = remaining
 
 

src/_pytest/nodes.py

@@ -144,6 +144,7 @@ class Node(abc.ABC, metaclass=NodeMeta):
     # Note that __dict__ is still available.
     __slots__ = (
         "__dict__",
+        "_deselected_reason",
         "_nodeid",
         "_store",
         "config",
@@ -214,6 +215,9 @@ def __init__(
         # Deprecated alias. Was never public. Can be removed in a few releases.
         self._store = self.stash
 
+        #: A reason for deselection.
+        self._deselected_reason = ""
+
     @classmethod
     def from_parent(cls, parent: Node, **kw) -> Self:
         """Public constructor for Nodes.

src/_pytest/terminal.py

@@ -1452,7 +1452,12 @@ def _build_collect_only_summary_stats_line(
         if errors:
             main_color = _color_for_type["error"]
             parts += [("%d %s" % pluralize(errors, "error"), {main_color: True})]  # noqa: UP031
-
+        if self.verbosity >= 2:
+            for item in self.stats["deselected"]:
+                self.write_line(
+                    f"Deselected: {item.nodeid}: {item._deselected_reason}",
+                    cyan=True,
+                )
         return parts, main_color