feat(AIP-122): disallow embedded resource (#1245)

docs/rules/0122/embedded-resource.md

@@ -0,0 +1,107 @@
+---
+rule:
+  aip: 122
+  name: [core, '0122', embedded-resource]
+  summary: Resource references should not be embedded resources.
+permalink: /122/embedded-resource
+redirect_from:
+  - /0122/embedded-resource
+---
+
+# Resource reference type
+
+This rule enforces that references to resource are via
+`google.api.resource_reference`, not by embedding the resource message, as
+mandated in [AIP-122][].
+
+## Details
+
+This rule complains if it sees a resource field of type `message` that is also
+annotated as a `google.api.resource`.
+
+## Examples
+
+**Incorrect** code for this rule:
+
+```proto
+// Incorrect.
+message Book {
+  option (google.api.resource) = {
+    type: "library.googleapis.com/Book"
+    pattern: "books/{book}"
+  };
+  string name = 1;
+
+  // Incorrect. Resource references should not be embedded resource messages.
+  Author author = 2;
+}
+
+message Author {
+    option (google.api.resource) = {
+        type: "library.googleapis.com/Author"
+        pattern: "authors/{author}"
+    };
+
+    string name = 1;
+}
+```
+
+**Correct** code for this rule:
+
+```proto
+// Correct.
+message Book {
+  option (google.api.resource) = {
+    type: "library.googleapis.com/Book"
+    pattern: "books/{book}"
+  };
+  string name = 1;
+
+  string author = 2 [(google.api.resource_reference) = {
+    type: "library.googleapis.com/Author"
+  }];
+}
+
+message Author {
+    option (google.api.resource) = {
+        type: "library.googleapis.com/Author"
+        pattern: "authors/{author}"
+    };
+
+    string name = 1;
+}
+```
+
+## Disabling
+
+If you need to violate this rule, use a leading comment above the method.
+Remember to also include an [aip.dev/not-precedent][] comment explaining why.
+
+```proto
+message Book {
+  option (google.api.resource) = {
+    type: "library.googleapis.com/Book"
+    pattern: "books/{book}"
+  };
+  string name = 1;
+
+  // (-- api-linter: core::0122::embedded-resource=disabled
+  //     aip.dev/not-precedent: We need to do this because reasons. --)
+  Author author = 2;
+}
+
+message Author {
+    option (google.api.resource) = {
+        type: "library.googleapis.com/Author"
+        pattern: "authors/{author}"
+    };
+
+    string name = 1;
+}
+```
+
+If you need to violate this rule for an entire file, place the comment at the
+top of the file.
+
+[aip-122]: https://aip.dev/122
+[aip.dev/not-precedent]: https://aip.dev/not-precedent

rules/aip0122/aip0122.go

@@ -29,5 +29,6 @@ func AddRules(r lint.RuleRegistry) error {
 		nameSuffix,
 		resourceReferenceType,
 		resourceIdOutputOnly,
+		embeddedResource,
 	)
 }

rules/aip0122/embedded_resource.go

@@ -0,0 +1,54 @@
+// 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 aip0122
+
+import (
+	"fmt"
+
+	"github.com/googleapis/api-linter/lint"
+	"github.com/googleapis/api-linter/rules/internal/utils"
+	"github.com/jhump/protoreflect/desc"
+)
+
+var embeddedResource = &lint.MessageRule{
+	Name:   lint.NewRuleName(122, "embedded-resource"),
+	OnlyIf: utils.IsResource,
+	LintMessage: func(m *desc.MessageDescriptor) []lint.Problem {
+		var problems []lint.Problem
+		for _, f := range m.GetFields() {
+			mt := f.GetMessageType()
+			if mt == nil || !utils.IsResource(mt) {
+				continue
+			}
+
+			r := utils.GetResource(mt)
+			if utils.IsResourceRevision(m) && utils.IsRevisionRelationship(r, utils.GetResource(m)) {
+				continue
+			}
+
+			suggestion := fmt.Sprintf(`string %s = %d [(google.api.resource_reference).type = %q];`, f.GetName(), f.GetNumber(), r.GetType())
+			if f.IsRepeated() {
+				suggestion = fmt.Sprintf("repeated %s", suggestion)
+			}
+			problems = append(problems, lint.Problem{
+				Message:    "refer to a resource by name, not by embedding the resource message",
+				Descriptor: f,
+				Suggestion: suggestion,
+			})
+		}
+
+		return problems
+	},
+}

rules/aip0122/embedded_resource_test.go

@@ -0,0 +1,159 @@
+// Copyright 2022 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 aip0122
+
+import (
+	"testing"
+
+	"github.com/googleapis/api-linter/rules/internal/testutils"
+)
+
+func TestEmbeddedResource(t *testing.T) {
+	for _, test := range []struct {
+		name           string
+		FieldA, FieldB string
+		problems       testutils.Problems
+	}{
+		{"Valid", "", "", nil},
+		{
+			"ValidReferences",
+			`string library = 2 [(google.api.resource_reference).type = "library.googleapis.com/Library"];`,
+			`string librarian = 3 [(google.api.resource_reference).type = "library.googleapis.com/Librarian"];`,
+			nil,
+		},
+		{
+			"InvalidEmbeddedResources",
+			"Library library = 2;",
+			"Librarian librarian = 3;",
+			testutils.Problems{
+				{
+					Message:    "not by embedding",
+					Suggestion: `string library = 2 [(google.api.resource_reference).type = "library.googleapis.com/Library"];`,
+				},
+				{
+					Message:    "not by embedding",
+					Suggestion: `string librarian = 3 [(google.api.resource_reference).type = "library.googleapis.com/Librarian"];`,
+				},
+			},
+		},
+		{
+			"InvalidRepeatedEmbeddedResource",
+			"repeated Library library = 2;",
+			"",
+			testutils.Problems{{
+				Message:    "not by embedding",
+				Suggestion: `repeated string library = 2 [(google.api.resource_reference).type = "library.googleapis.com/Library"];`,
+			}},
+		},
+	} {
+		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;
+
+				{{.FieldA}}
+
+				{{.FieldB}}
+			}
+
+			message Library {
+				option (google.api.resource) = {
+					type: "library.googleapis.com/Library"
+					pattern: "libraries/{library}"
+				};
+				string name = 1;
+			}
+
+			message Librarian {
+				option (google.api.resource) = {
+					type: "library.googleapis.com/Librarian"
+					pattern: "libraries/{library}/librarians/{librarian}"
+				};
+				string name = 1;
+			}
+		`, test)
+			m := f.FindMessage("Book")
+
+			want := test.problems
+			if len(want) > 0 {
+				want[0].Descriptor = m.FindFieldByName("library")
+			}
+			if len(want) > 1 {
+				want[1].Descriptor = m.FindFieldByName("librarian")
+			}
+			if diff := want.Diff(embeddedResource.Lint(f)); diff != "" {
+				t.Errorf(diff)
+			}
+		})
+	}
+}
+
+func TestEmbeddedResource_Revisions(t *testing.T) {
+	for _, test := range []struct {
+		name         string
+		SnapshotType string
+		problems     testutils.Problems
+	}{
+		{"Valid", "Book", nil},
+		{
+			"InvalidEmbeddedResource",
+			"Library",
+			testutils.Problems{{
+				Message:    "not by embedding",
+				Suggestion: `string snapshot = 2 [(google.api.resource_reference).type = "library.googleapis.com/Library"];`,
+			}},
+		},
+	} {
+		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 BookRevision {
+				option (google.api.resource) = {
+					type: "library.googleapis.com/BookRevision"
+					pattern: "publishers/{publisher}/books/{book}/revisions/{revision}"
+				};
+				string name = 1;
+
+				{{.SnapshotType}} snapshot = 2;
+			}
+
+			message Library {
+				option (google.api.resource) = {
+					type: "library.googleapis.com/Library"
+					pattern: "libraries/{library}"
+				};
+				string name = 1;
+			}
+		`, test)
+			field := f.FindMessage("BookRevision").FindFieldByName("snapshot")
+			if diff := test.problems.SetDescriptor(field).Diff(embeddedResource.Lint(f)); diff != "" {
+				t.Errorf(diff)
+			}
+		})
+	}
+}

rules/internal/utils/resource.go

@@ -15,6 +15,9 @@
 package utils
 
 import (
+	"strings"
+
+	"github.com/jhump/protoreflect/desc"
 	apb "google.golang.org/genproto/googleapis/api/annotations"
 )
 
@@ -62,3 +65,28 @@ func GetResourceNameField(r *apb.ResourceDescriptor) string {
 	}
 	return "name"
 }
+
+// IsResourceRevision determines if the given message represents a resource
+// revision as described in AIP-162.
+func IsResourceRevision(m *desc.MessageDescriptor) bool {
+	return IsResource(m) && strings.HasSuffix(m.GetName(), "Revision")
+}
+
+// IsRevisionRelationship determines if the "revision" resource is actually
+// a revision of the "parent" resource.
+func IsRevisionRelationship(parent, revision *apb.ResourceDescriptor) bool {
+	_, pType, ok := SplitResourceTypeName(parent.GetType())
+	if !ok {
+		return false
+	}
+	_, rType, ok := SplitResourceTypeName(revision.GetType())
+	if !ok {
+		return false
+	}
+
+	if !strings.HasSuffix(rType, "Revision") {
+		return false
+	}
+	rType = strings.TrimSuffix(rType, "Revision")
+	return pType == rType
+}