Review feedback and test fix.

# Delete this line to force CI to run Clippy and the Rust tests.
[ci skip-rust-tests]
# Delete this line to force CI to run the JVM tests.
[ci skip-jvm-tests]

src/python/pants/backend/python/lint/isort/rules.py

@@ -43,7 +43,7 @@ class IsortFieldSet(FieldSetWithOrigin):
     sources: PythonSources
 
 
-class IsortRequest(FmtRequest):
+class IsortRequest(FmtRequest, LintRequest):
     field_set_type = IsortFieldSet
 
 

src/python/pants/backend/python/lint/python_fmt_integration_test.py

@@ -3,9 +3,9 @@
 
 from typing import List, Optional
 
-from pants.backend.python.lint.black.rules import BlackFieldSets
+from pants.backend.python.lint.black.rules import BlackRequest
 from pants.backend.python.lint.black.rules import rules as black_rules
-from pants.backend.python.lint.isort.rules import IsortFieldSets
+from pants.backend.python.lint.isort.rules import IsortRequest
 from pants.backend.python.lint.isort.rules import rules as isort_rules
 from pants.backend.python.lint.python_fmt import PythonFmtTargets, format_python_target
 from pants.backend.python.target_types import PythonLibrary
@@ -29,8 +29,8 @@ def rules(cls):
             *black_rules(),
             *isort_rules(),
             RootRule(PythonFmtTargets),
-            RootRule(BlackFieldSets),
-            RootRule(IsortFieldSets),
+            RootRule(BlackRequest),
+            RootRule(IsortRequest),
         )
 
     def run_black_and_isort(
@@ -93,7 +93,7 @@ def test_skipped_formatter(self) -> None:
 
     def test_no_changes(self) -> None:
         source = FileContent(
-            "test/skipped.py", content=b"from animals import dog, cat\n\nprint('hello')\n",
+            "test/target.py", content=b'from animals import cat, dog\n\nprint("hello")\n',
         )
         results = self.run_black_and_isort([source], name="different_file")
         assert results.output == self.get_digest([source])

src/python/pants/core/goals/fmt.py

@@ -5,7 +5,7 @@
 from dataclasses import dataclass
 from typing import ClassVar, Iterable, List, Tuple, Type
 
-from pants.core.goals.style import StyleRequest
+from pants.core.goals.style_request import StyleRequest
 from pants.core.util_rules.filter_empty_sources import TargetsWithSources, TargetsWithSourcesRequest
 from pants.engine.console import Console
 from pants.engine.fs import EMPTY_DIGEST, Digest, DirectoryToMaterialize, MergeDigests, Workspace
@@ -58,7 +58,10 @@ def did_change(self) -> bool:
 
 @union
 class FmtRequest(StyleRequest):
-    """A union for StyleRequests that should be formattable."""
+    """A union for StyleRequests that should be formattable.
+
+    Subclass and install a member of this type to provide a formatter.
+    """
 
 
 @union

src/python/pants/core/goals/lint.py

@@ -4,7 +4,7 @@
 from dataclasses import dataclass
 from typing import Iterable
 
-from pants.core.goals.style import StyleRequest
+from pants.core.goals.style_request import StyleRequest
 from pants.core.util_rules.filter_empty_sources import (
     FieldSetsWithSources,
     FieldSetsWithSourcesRequest,
@@ -47,7 +47,10 @@ def prep_output(s: bytes) -> str:
 
 @union
 class LintRequest(StyleRequest):
-    """A union for StyleRequests that should be lintable."""
+    """A union for StyleRequests that should be lintable.
+
+    Subclass and install a member of this type to provide a linter.
+    """
 
 
 class LintOptions(GoalSubsystem):
@@ -101,16 +104,13 @@ async def lint(
         )
         for lint_request_type in union_membership[LintRequest]
     )
-    lint_requests_with_sources: Iterable[FieldSetsWithSources] = await MultiGet(
+    field_sets_with_sources: Iterable[FieldSetsWithSources] = await MultiGet(
         Get[FieldSetsWithSources](FieldSetsWithSourcesRequest(lint_request.field_sets))
         for lint_request in lint_requests
     )
-    # NB: We must convert back the generic FieldSetsWithSources objects back into their
-    # corresponding LintRequest, e.g. back to IsortFieldSets, in order for the union rule to
-    # work.
     valid_lint_requests: Iterable[StyleRequest] = tuple(
         lint_request_cls(lint_request)
-        for lint_request_cls, lint_request in zip(lint_request_types, lint_requests_with_sources)
+        for lint_request_cls, lint_request in zip(lint_request_types, field_sets_with_sources)
         if lint_request
     )
 

src/python/pants/core/goals/lint_test.py

@@ -127,13 +127,13 @@ def make_target_with_origin(address: Optional[Address] = None) -> TargetWithOrig
     @staticmethod
     def run_lint_rule(
         *,
-        field_set_collection_types: List[Type[LintRequest]],
+        lint_request_types: List[Type[LintRequest]],
         targets: List[TargetWithOrigin],
         per_target_caching: bool,
         include_sources: bool = True,
     ) -> Tuple[int, str]:
         console = MockConsole(use_colors=False)
-        union_membership = UnionMembership({LintRequest: field_set_collection_types})
+        union_membership = UnionMembership({LintRequest: lint_request_types})
         result: Lint = run_rule(
             lint,
             rule_args=[
@@ -164,7 +164,7 @@ def run_lint_rule(
     def test_empty_target_noops(self) -> None:
         def assert_noops(per_target_caching: bool) -> None:
             exit_code, stderr = self.run_lint_rule(
-                field_set_collection_types=[FailingFieldSets],
+                lint_request_types=[FailingFieldSets],
                 targets=[self.make_target_with_origin()],
                 per_target_caching=per_target_caching,
                 include_sources=False,
@@ -178,7 +178,7 @@ def assert_noops(per_target_caching: bool) -> None:
     def test_invalid_target_noops(self) -> None:
         def assert_noops(per_target_caching: bool) -> None:
             exit_code, stderr = self.run_lint_rule(
-                field_set_collection_types=[InvalidFieldSets],
+                lint_request_types=[InvalidFieldSets],
                 targets=[self.make_target_with_origin()],
                 per_target_caching=per_target_caching,
             )
@@ -194,7 +194,7 @@ def test_single_target_with_one_linter(self) -> None:
 
         def assert_expected(per_target_caching: bool) -> None:
             exit_code, stderr = self.run_lint_rule(
-                field_set_collection_types=[FailingFieldSets],
+                lint_request_types=[FailingFieldSets],
                 targets=[target_with_origin],
                 per_target_caching=per_target_caching,
             )
@@ -215,7 +215,7 @@ def test_single_target_with_multiple_linters(self) -> None:
 
         def assert_expected(per_target_caching: bool) -> None:
             exit_code, stderr = self.run_lint_rule(
-                field_set_collection_types=[SuccessfulFieldSets, FailingFieldSets],
+                lint_request_types=[SuccessfulFieldSets, FailingFieldSets],
                 targets=[target_with_origin],
                 per_target_caching=per_target_caching,
             )
@@ -239,7 +239,7 @@ def test_multiple_targets_with_one_linter(self) -> None:
 
         def get_stderr(*, per_target_caching: bool) -> str:
             exit_code, stderr = self.run_lint_rule(
-                field_set_collection_types=[ConditionallySucceedsFieldSets],
+                lint_request_types=[ConditionallySucceedsFieldSets],
                 targets=[
                     self.make_target_with_origin(good_address),
                     self.make_target_with_origin(bad_address),
@@ -272,7 +272,7 @@ def test_multiple_targets_with_multiple_linters(self) -> None:
 
         def get_stderr(*, per_target_caching: bool) -> str:
             exit_code, stderr = self.run_lint_rule(
-                field_set_collection_types=[ConditionallySucceedsFieldSets, SuccessfulFieldSets,],
+                lint_request_types=[ConditionallySucceedsFieldSets, SuccessfulFieldSets,],
                 targets=[
                     self.make_target_with_origin(good_address),
                     self.make_target_with_origin(bad_address),

src/python/pants/core/goals/style.py → src/python/pants/core/goals/style_request.py

@@ -18,7 +18,8 @@
 class StyleRequest(Generic[_FS], metaclass=ABCMeta):
     """A request to style a collection of `FieldSet`s.
 
-    Should be subclassed for a particular style engine.
+    Should be subclassed for a particular style engine in order to support autoformatting or
+    linting.
     """
 
     field_set_type: ClassVar[Type[_FS]]