feat(aip-136): response message name

docs/rules/0136/response-message-name.md

@@ -0,0 +1,113 @@
+---
+rule:
+  aip: 136
+  name: [core, '0136', response-message-name]
+  summary: Custom methods must have standardized response message names.
+permalink: /136/response-message-name
+redirect_from:
+  - /0136/response-message-name
+---
+
+# Custom methods: Response message
+
+This rule enforces that all custom methods should take a response message
+matching the RPC name, with a `Response` suffix, or the resource being operated
+on [AIP-136][].
+
+## Details
+
+This rule looks at any method that is not a standard method, and complains if
+the name of the corresponding input message does not match the name of the RPC
+with the suffix `Response` appended, or the resource itself. It will use the
+`(google.api.resource_reference)` on the first field of the request message to
+determine the resource name that should be used.
+
+## Examples
+
+### Response Suffix
+
+**Incorrect** code for this rule:
+
+```proto
+// Incorrect.
+// Should be `ArchiveBookResponse`.
+rpc ArchiveBook(ArchiveBookRequest) returns (ArchiveBookResp) {
+  option (google.api.http) = {
+    post: "/v1/{name=publishers/*/books/*}:archive"
+    body: "*"
+  };
+}
+```
+
+**Correct** code for this rule:
+
+```proto
+// Correct.
+rpc ArchiveBook(ArchiveBookRequest) returns (ArchiveBookResponse) {
+  option (google.api.http) = {
+    post: "/v1/{name=publishers/*/books/*}:archive"
+    body: "*"
+  };
+
+```
+
+### Resource
+
+**Incorrect** code for this rule:
+
+```proto
+// Incorrect.
+// Should be `Book`.
+rpc ArchiveBook(ArchiveBookRequest) returns (Author) {
+  option (google.api.http) = {
+    post: "/v1/{name=publishers/*/books/*}:archive"
+    body: "*"
+  };
+}
+
+message ArchiveBookRequest {
+    // The book to archive.
+    // Format: publishers/{publisher}/books/{book}
+    string name = 1 [(google.api.resource_reference).type = "library.googleapis.com/Book"];
+}
+```
+
+**Correct** code for this rule:
+
+```proto
+// Correct.
+rpc ArchiveBook(ArchiveBookRequest) returns (Book) {
+  option (google.api.http) = {
+    post: "/v1/{name=publishers/*/books/*}:archive"
+    body: "*"
+  };
+}
+
+message ArchiveBookRequest {
+    // The book to archive.
+    // Format: publishers/{publisher}/books/{book}
+    string name = 1 [(google.api.resource_reference).type = "library.googleapis.com/Book"];
+}
+```
+
+## 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
+// (-- api-linter: core::0136::response-message-name=disabled
+//     aip.dev/not-precedent: We need to do this because reasons. --)
+rpc ArchiveBook(ArchiveBookRequest) returns (ArchiveBookResp) {
+  option (google.api.http) = {
+    post: "/v1/{name=publishers/*/books/*}:archive"
+    body: "*"
+  };
+}
+```
+
+If you need to violate this rule for an entire file, place the comment at the
+top of the file.
+
+[aip-136]: https://aip.dev/136
+[aip.dev/not-precedent]: https://aip.dev/not-precedent

rules/aip0136/aip0136.go

@@ -31,6 +31,7 @@ func AddRules(r lint.RuleRegistry) error {
 		httpBody,
 		httpMethod,
 		noPrepositions,
+		responseMessageName,
 		standardMethodsOnly,
 		uriSuffix,
 		verbNoun,

rules/aip0136/response_message_name.go

@@ -0,0 +1,64 @@
+// Copyright 2019 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 aip0136
+
+import (
+	"fmt"
+
+	"bitbucket.org/creachadair/stringset"
+	"github.com/googleapis/api-linter/lint"
+	"github.com/googleapis/api-linter/locations"
+	"github.com/googleapis/api-linter/rules/internal/utils"
+	"github.com/jhump/protoreflect/desc"
+)
+
+// Custom methods should return a response message matching the RPC name,
+// with a Response suffix.
+var responseMessageName = &lint.MethodRule{
+	Name:   lint.NewRuleName(135, "response-message-name"),
+	OnlyIf: isCustomMethod,
+	LintMethod: func(m *desc.MethodDescriptor) []lint.Problem {
+		matchingResponseName := m.GetName() + "Response"
+		suggestion := matchingResponseName
+
+		got := m.GetOutputType().GetName()
+		want := stringset.New(matchingResponseName)
+
+		// Get the resource name from the first request message field, if it
+		// is a resource reference
+		if len(m.GetInputType().GetFields()) > 0 {
+			rr := utils.GetResourceReference(m.GetInputType().GetFields()[0])
+			if _, resourceMsgNameSingular, ok := utils.SplitResourceTypeName(rr.GetType()); ok {
+				want.Add(resourceMsgNameSingular)
+				suggestion += " or " + resourceMsgNameSingular
+			}
+		}
+
+		if !want.Contains(got) {
+			msg := "Custom methods should return a response message matching the RPC name, with a Response suffix, or the resource, not %q."
+
+			problem := lint.Problem{
+				Message:    fmt.Sprintf(msg, got),
+				Suggestion: suggestion,
+				Descriptor: m,
+				Location:   locations.MethodResponseType(m),
+			}
+
+			return []lint.Problem{problem}
+		}
+
+		return nil
+	},
+}

rules/aip0136/response_message_name_test.go

@@ -0,0 +1,83 @@
+// Copyright 2019 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 aip0136
+
+import (
+	"testing"
+
+	"github.com/googleapis/api-linter/rules/internal/testutils"
+)
+
+func TestResponseMessageName(t *testing.T) {
+	// Set up the testing permutations.
+	tests := []struct {
+		testName            string
+		MethodName          string
+		RespMessageName     string
+		OperatingOnResource bool
+		problems            testutils.Problems
+	}{
+		{"Valid Resource", "ArchiveBook", "Book", true, testutils.Problems{}},
+		{"Invalid Resource", "ArchiveBook", "Author", true, testutils.Problems{{Suggestion: "ArchiveBookResponse or Book"}}},
+		{"Valid Response Suffix Stateful", "ArchiveBook", "ArchiveBookResponse", true, testutils.Problems{}},
+		{"Valid Response Suffix Stateless", "ArchiveBook", "ArchiveBookResponse", false, testutils.Problems{}},
+		{"Invalid Response Suffix", "ArchiveBook", "ArchiveBookResp", true, testutils.Problems{{Suggestion: "ArchiveBookResponse or Book"}}},
+		{"Unable To Find Resource", "ArchiveBook", "ArchiveBookResp", false, testutils.Problems{{Suggestion: "ArchiveBookResponse"}}},
+		{"Irrelevant", "DeleteBook", "DeleteBookResp", true, testutils.Problems{}},
+	}
+
+	// Run each test individually.
+	for _, test := range tests {
+		t.Run(test.testName, func(t *testing.T) {
+			file := testutils.ParseProto3Tmpl(t, `
+			package test;
+			import "google/api/resource.proto";
+			service Library {
+				rpc {{.MethodName}}({{.MethodName}}Request) returns ({{.RespMessageName}});
+			}
+			message {{.MethodName}}Request {
+				{{ if (.OperatingOnResource) }}
+				// The book to archive.
+				// Format: publishers/{publisher}/books/{book}
+				string name = 1 [
+				  (google.api.resource_reference) = {
+					type: "library.googleapis.com/Book"
+				  }];
+				{{ end }}
+			}
+			message Book {
+				option (google.api.resource) = {
+					type: "library.googleapis.com/Book"
+					pattern: "publishers/{publisher}/books/{book}"
+				};
+			}
+			message Author {
+				option (google.api.resource) = {
+					type: "library.googleapis.com/Author"
+					pattern: "authors/{author}"
+				};
+			}
+			{{ if and (ne .RespMessageName "Book") (ne .RespMessageName "Author") }}
+			message {{.RespMessageName}} {}
+			{{ end }}
+			`, test)
+			method := file.GetServices()[0].GetMethods()[0]
+			problems := responseMessageName.Lint(file)
+			if diff := test.problems.SetDescriptor(method).Diff(problems); diff != "" {
+				t.Error(diff)
+			}
+		})
+	}
+}