Add integration test

src/python/pants/build_graph/build_configuration.py

@@ -14,7 +14,7 @@
 from pants.build_graph.build_file_aliases import BuildFileAliases
 from pants.core.util_rules.environments import EnvironmentsSubsystem
 from pants.engine.goal import GoalSubsystem
-from pants.engine.rules import Rule, RuleIndex, TaskRule
+from pants.engine.rules import DeleteRule, Rule, RuleIndex, TaskRule
 from pants.engine.target import Target
 from pants.engine.unions import UnionRule
 from pants.option.alias import CliOptions
@@ -216,7 +216,9 @@ def register_subsystems(
             for subsystem in subsystems:
                 self._subsystem_to_providers[subsystem].append(plugin_or_backend)
 
-        def register_rules(self, plugin_or_backend: str, rules: Iterable[Rule | UnionRule]):
+        def register_rules(
+            self, plugin_or_backend: str, rules: Iterable[Rule | UnionRule | DeleteRule]
+        ):
             """Registers the given rules."""
             if not isinstance(rules, Iterable):
                 raise TypeError(f"The rules must be an iterable, given {rules!r}")

src/python/pants/engine/delete_rule_integration_test.py

@@ -0,0 +1,55 @@
+# Copyright 2024 Pants project contributors (see CONTRIBUTORS.md).
+# Licensed under the Apache License, Version 2.0 (see LICENSE).
+from dataclasses import dataclass
+
+from pants.engine.rules import DeleteRule, collect_rules, rule
+from pants.testutil.rule_runner import QueryRule, RuleRunner
+
+
+@dataclass(frozen=True)
+class IntRequest:
+    pass
+
+
+@rule
+async def original_rule(request: IntRequest) -> int:
+    return 0
+
+
+@rule
+def new_rule(request: IntRequest) -> int:
+    return 42
+
+
+def test_delete() -> None:
+    rule_runner = RuleRunner(
+        target_types=[],
+        rules=[
+            *collect_rules(
+                {
+                    "original_rule": original_rule,
+                }
+            ),
+            QueryRule(int, [IntRequest]),
+        ],
+    )
+
+    result = rule_runner.request(int, [IntRequest()])
+    assert result == 0
+
+    rule_runner = RuleRunner(
+        target_types=[],
+        rules=[
+            *collect_rules(
+                {
+                    "original_rule": original_rule,
+                    "new_rule": new_rule,
+                }
+            ),
+            DeleteRule.create(original_rule),
+            QueryRule(int, [IntRequest]),
+        ],
+    )
+
+    result = rule_runner.request(int, [IntRequest()])
+    assert result == 42

src/python/pants/engine/rules.py

@@ -538,7 +538,7 @@ class RuleIndex:
     union_rules: FrozenOrderedSet[UnionRule]
 
     @classmethod
-    def create(cls, rule_entries: Iterable[Rule | UnionRule]) -> RuleIndex:
+    def create(cls, rule_entries: Iterable[Rule | UnionRule | DeleteRule]) -> RuleIndex:
         """Creates a RuleIndex with tasks indexed by their output type."""
         rules: OrderedSet[TaskRule] = OrderedSet()
         delete_rules: OrderedSet[DeleteRule] = OrderedSet()