feat(AIP-135): add cascading delete force-field rule

docs/rules/0135/force-field.md

@@ -0,0 +1,73 @@
+---
+rule:
+  aip: 135
+  name: [core, '0135', force-field]
+  summary: Delete RPCs for resources with child collections should have a `force` field in the request.
+permalink: /135/force-field
+redirect_from:
+  - /0135/force-field
+---
+
+# Delete methods: Name field
+
+This rule enforces that the standard `Delete` method for a resource that parents
+other resources in the service have a `bool force` field in the request message,
+as mandated in [AIP-135][].
+
+## Details
+
+This rule looks at any message matching `Delete*Request` for a resource with
+child resources in the same service and complains if the `force` field is
+missing.
+
+## Examples
+
+**Incorrect** code for this rule:
+
+```proto
+// Incorrect.
+message DeletePublisherRequest {
+  // Where Publisher parents the Book resource.
+  string name = 1 [
+    (google.api.resource_reference).type = "library.googleapis.com/Publisher"]; 
+
+  // Missing `bool force` field.
+}
+```
+
+**Correct** code for this rule:
+
+```proto
+// Correct.
+message DeletePublisherRequest {
+  // Where Publisher parents the Book resource.
+  string name = 1 [
+    (google.api.resource_reference).type = "library.googleapis.com/Publisher"]; 
+
+  // If set to true, any books from this publisher will also be deleted.
+  // (Otherwise, the request will only work if the publisher has no books.)
+  bool force = 2;
+}
+```
+
+## Disabling
+
+If you need to violate this rule, use a leading comment above the message (if
+the `name` field is missing) or above the field (if it is the wrong type).
+Remember to also include an [aip.dev/not-precedent][] comment explaining why.
+
+```proto
+// (-- api-linter: core::0135::force-field=disabled
+//     aip.dev/not-precedent: We need to do this because reasons. --)
+message DeletePublisherRequest {
+  // Where Publisher parents the Book resource.
+  string name = 1 [
+    (google.api.resource_reference).type = "library.googleapis.com/Publisher"]; 
+}
+```
+
+If you need to violate this rule for an entire file, place the comment at the
+top of the file.
+
+[aip-135]: https://aip.dev/135#cascading-delete
+[aip.dev/not-precedent]: https://aip.dev/not-precedent

rules/aip0135/aip0135.go

@@ -27,6 +27,7 @@ import (
 func AddRules(r lint.RuleRegistry) error {
 	return r.Register(
 		135,
+		forceField,
 		httpBody,
 		httpMethod,
 		httpNameField,

rules/aip0135/force_field.go

@@ -0,0 +1,51 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package aip0135
+
+import (
+	"github.com/googleapis/api-linter/lint"
+	"github.com/googleapis/api-linter/rules/internal/utils"
+	"github.com/jhump/protoreflect/desc"
+)
+
+// Delete methods for resources that are parents should have a bool force field.
+var forceField = &lint.MessageRule{
+	Name: lint.NewRuleName(135, "force-field"),
+	OnlyIf: func(m *desc.MessageDescriptor) bool {
+		name := m.FindFieldByName("name")
+		ref := utils.GetResourceReference(name)
+		validRef := ref != nil && ref.GetType() != "" && utils.FindResource(ref.GetType(), m.GetFile()) != nil
+
+		return isDeleteRequestMessage(m) && validRef
+	},
+	LintMessage: func(m *desc.MessageDescriptor) []lint.Problem {
+		force := m.FindFieldByName("force")
+		name := m.FindFieldByName("name")
+		ref := utils.GetResourceReference(name)
+		res := utils.FindResource(ref.GetType(), m.GetFile())
+
+		children := utils.FindResourceChildren(res, m.GetFile())
+		if len(children) > 0 && force == nil {
+			return []lint.Problem{
+				{
+					Message:    "Delete requests for resources with children should have a `bool force` field",
+					Descriptor: m,
+				},
+			}
+		}
+
+		return nil
+	},
+}

rules/aip0135/force_field_test.go

@@ -0,0 +1,72 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package aip0135
+
+import (
+	"testing"
+
+	"github.com/googleapis/api-linter/rules/internal/testutils"
+)
+
+func TestForceField(t *testing.T) {
+	tests := []struct {
+		name      string
+		Reference string
+		BoolField string
+		problems  testutils.Problems
+	}{
+		{"ValidWithChildren", `.type = "library.googleapis.com/Publisher"`, "force", nil},
+		{"ValidWithoutChildren", `.type = "library.googleapis.com/Book"`, "other", nil},
+		{"SkipIncorrectChildTypeReference", `.child_type = "library.googleapis.com/Publisher"`, "other", nil},
+		{"InvalidMissingForce", `.type = "library.googleapis.com/Publisher"`, "other", testutils.Problems{{Message: "bool force"}}},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			f := testutils.ParseProto3Tmpl(t, `
+				import "google/api/resource.proto";
+
+				message Book {
+					option (google.api.resource) = {
+						type: "library.googleapis.com/Book"
+						pattern: "publishers/{publisher}/books/{book}"
+					};
+
+					string name = 1;
+				}
+
+				message Publisher {
+					option (google.api.resource) = {
+						type: "library.googleapis.com/Publisher"
+						pattern: "publishers/{publisher}"
+					};
+
+					string name = 1;
+				}
+
+				message DeleteResourceRequest {
+					string name = 1 [(google.api.resource_reference){{.Reference}}];
+
+					bool {{.BoolField}} = 2;
+				}
+			`, test)
+			msg := f.FindMessage("DeleteResourceRequest")
+			problems := forceField.Lint(f)
+			if diff := test.problems.SetDescriptor(msg).Diff(problems); diff != "" {
+				t.Errorf("Problems did not match: %v", diff)
+			}
+		})
+	}
+}

rules/internal/utils/extension.go

@@ -160,6 +160,9 @@ func GetResourceDefinitions(f *desc.FileDescriptor) []*apb.ResourceDescriptor {
 
 // GetResourceReference returns the google.api.resource_reference annotation.
 func GetResourceReference(f *desc.FieldDescriptor) *apb.ResourceReference {
+	if f == nil {
+		return nil
+	}
 	opts := f.GetFieldOptions()
 	if x := proto.GetExtension(opts, apb.E_ResourceReference); x != nil {
 		return x.(*apb.ResourceReference)
@@ -200,3 +203,33 @@ func SplitResourceTypeName(typ string) (service string, typeName string, ok bool
 
 	return
 }
+
+// FindResourceChildren attempts to search for other resources defined in the
+// package that are parented by the given resource.
+func FindResourceChildren(parent *apb.ResourceDescriptor, file *desc.FileDescriptor) []*apb.ResourceDescriptor {
+	pats := parent.GetPattern()
+	if len(pats) == 0 {
+		return nil
+	}
+	// Use the first pattern in the resource because:
+	// 1. Patterns cannot be rearranged, so this is the true first pattern
+	// 2. The true first pattern is the one most likely to be used as a parent.
+	first := pats[0]
+
+	var children []*apb.ResourceDescriptor
+	files := append(file.GetDependencies(), file)
+	for _, f := range files {
+		for _, m := range f.GetMessageTypes() {
+			if r := GetResource(m); r != nil && r.GetType() != parent.GetType() {
+				for _, p := range r.GetPattern() {
+					if strings.HasPrefix(p, first) {
+						children = append(children, r)
+						break
+					}
+				}
+			}
+		}
+	}
+
+	return children
+}

rules/internal/utils/extension_test.go

@@ -20,6 +20,8 @@ import (
 	"bitbucket.org/creachadair/stringset"
 	"github.com/google/go-cmp/cmp"
 	"github.com/googleapis/api-linter/rules/internal/testutils"
+	apb "google.golang.org/genproto/googleapis/api/annotations"
+	"google.golang.org/protobuf/proto"
 )
 
 func TestGetFieldBehavior(t *testing.T) {
@@ -471,3 +473,91 @@ func TestGetOutputOrLROResponseMessage(t *testing.T) {
 		})
 	}
 }
+
+func TestFindResourceChildren(t *testing.T) {
+	publisher := &apb.ResourceDescriptor{
+		Type: "library.googleapis.com/Publisher",
+		Pattern: []string{
+			"publishers/{publisher}",
+		},
+	}
+	shelf := &apb.ResourceDescriptor{
+		Type: "library.googleapis.com/Shelf",
+		Pattern: []string{
+			"shelves/{shelf}",
+		},
+	}
+	book := &apb.ResourceDescriptor{
+		Type: "library.googleapis.com/Book",
+		Pattern: []string{
+			"publishers/{publisher}/books/{book}",
+		},
+	}
+	edition := &apb.ResourceDescriptor{
+		Type: "library.googleapis.com/Edition",
+		Pattern: []string{
+			"publishers/{publisher}/books/{book}/editions/{edition}",
+		},
+	}
+	files := testutils.ParseProtoStrings(t, map[string]string{
+		"book.proto": `
+			syntax = "proto3";
+			package test;
+
+			import "google/api/resource.proto";
+
+			message Book {
+				option (google.api.resource) = {
+					type: "library.googleapis.com/Book"
+					pattern: "publishers/{publisher}/books/{book}"
+				};
+
+				string name = 1;
+			}
+
+			message Edition {
+				option (google.api.resource) = {
+					type: "library.googleapis.com/Edition"
+					pattern: "publishers/{publisher}/books/{book}/editions/{edition}"
+				};
+
+				string name = 1;
+			}
+		`,
+		"shelf.proto": `
+			syntax = "proto3";
+			package test;
+
+			import "book.proto";
+			import "google/api/resource.proto";
+
+			message Shelf {
+				option (google.api.resource) = {
+					type: "library.googleapis.com/Shelf"
+					pattern: "shelves/{shelf}"
+				};
+
+				string name = 1;
+
+				repeated Book books = 2;
+			}
+		`,
+	})
+
+	for _, tst := range []struct {
+		name   string
+		parent *apb.ResourceDescriptor
+		want   []*apb.ResourceDescriptor
+	}{
+		{"has_child_same_file", book, []*apb.ResourceDescriptor{edition}},
+		{"has_child_other_file", publisher, []*apb.ResourceDescriptor{book, edition}},
+		{"no_children", shelf, nil},
+	} {
+		t.Run(tst.name, func(t *testing.T) {
+			got := FindResourceChildren(tst.parent, files["shelf.proto"])
+			if diff := cmp.Diff(tst.want, got, cmp.Comparer(proto.Equal)); diff != "" {
+				t.Errorf("got(-),want(+):\n%s", diff)
+			}
+		})
+	}
+}