Add linter plugin to check for array responses

.gitignore

@@ -7,6 +7,10 @@
 # Swift
 .build
 Packages
+# Node
+node_modules
+package-lock.json
+bundle.json
 # vi
 *.swp
 # vscode

linters/node/gnostic-lint-responses/Makefile

@@ -0,0 +1,19 @@
+
+GNOSTIC = $(GOPATH)/src/github.com/googleapis/gnostic
+
+plugin:
+	node_modules/.bin/pbjs -t json \
+		$(GNOSTIC)/OpenAPIv2/OpenAPIv2.proto \
+		$(GNOSTIC)/OpenAPIv3/OpenAPIv3.proto \
+		$(GNOSTIC)/discovery/discovery.proto \
+		$(GNOSTIC)/surface/surface.proto \
+		$(GNOSTIC)/plugins/plugin.proto \
+		> bundle.json
+	node_modules/.bin/nexe gnostic-lint-responses.js
+	mv gnostic-lint-responses $(GOPATH)/bin
+
+run:	plugin
+	gnostic $(GNOSTIC)/examples/v2.0/yaml/petstore.yaml --lint-responses
+
+setup:
+	npm install

linters/node/gnostic-lint-responses/README.md

@@ -0,0 +1,15 @@
+This directory contains a gnostic linter written with node.
+
+It is built using [dcodeIO/Protobuf.js](https://github.com/dcodeIO/ProtoBuf.js).
+
+### SETUP
+
+- Install node.
+- Run `make setup` to install node dependencies.
+
+### TRY IT
+
+- Run `make run` to test-run the plugin.
+
+
+

linters/node/gnostic-lint-responses/gnostic-lint-responses.js

@@ -0,0 +1,83 @@
+// import libraries
+const protobuf = require("protobufjs");
+const getStdin = require("get-stdin");
+const find = require("lodash/find");
+const forEach = require("lodash/forEach");
+const pick = require("lodash/pick");
+
+// import messages
+const root = protobuf.Root.fromJSON(require("./bundle.json"));
+const Request = root.lookupType("gnostic.plugin.v1.Request");
+const Response = root.lookupType("gnostic.plugin.v1.Response");
+const Document = root.lookupType("openapi.v2.Document");
+
+getStdin.buffer().then(buffer => {
+  const request = Request.decode(buffer);
+  var messages = [];
+  for (var j in request.models) {
+    const m = request.models[j];
+    if (m.type_url == "openapi.v2.Document") {
+      const openapi2 = Document.decode(m.value);
+      const paths = openapi2.paths.path;
+      for (var i in paths) {
+        const path = paths[i];
+        // console.error('path %s\n\n', path.name)
+
+        // Arrays MUST NOT be returned as the top-level structure in a response body.
+        let pathOps = pick(path.value, ["get","head","post", "put", "patch", "delete", "options"]);
+        forEach(pathOps, (op, opKey) => {
+          if (op != null) {
+            forEach(op.responses.responseCode, responseObj => {
+              // console.error('responseObj is %j', responseObj)
+              name = responseObj.name;
+              response = responseObj.value.response;
+              if (response.schema && response.schema.schema) {
+                if (!response.schema.schema._ref) {
+                  if (
+                    response.schema.schema.type != null &&
+                    response.schema.schema.type.value == "array"
+                  ) {
+                    messages.push({
+                      level: 3,
+                      code: "NO_ARRAY_RESPONSES",
+                      text: "Arrays MUST NOT be returned as the top-level structure in a response body.",
+                      keys: ["paths", path.name, opKey, "responses", name, "schema"]
+                    });
+                  }
+                } else {
+                  let schemaName = response.schema.schema._ref.match(/#\/definitions\/(\w+)/);
+                  if (schemaName) {
+                    const definitions = openapi2.definitions.additionalProperties;
+                    const schemaKvp = find(definitions, {name: schemaName[1]
+                    });
+                    //console.error('schemaKvp.value.type = %s', schemaKvp.value.type.value)
+                    if (schemaKvp && schemaKvp.value.type && schemaKvp.value.type.value.indexOf("array") >= 0) {
+                      messages.push({
+                        level: 3,
+                        code: "NO_ARRAY_RESPONSES",
+                        text: "Arrays MUST NOT be returned as the top-level structure in a response body.",
+                        keys: ["paths", path.name, opKey, "responses", name, "schema" ]
+                      });
+                    }
+                  }
+                }
+              }
+            });
+          }
+        });
+      }
+    }
+  }
+
+  const payload = {
+    messages: messages
+  };
+
+  // Verify the payload if necessary (i.e. when possibly incomplete or invalid)
+  const errMsg = Response.verify(payload);
+  if (errMsg) throw Error(errMsg);
+
+  const message = Response.create(payload);
+  process.stdout.write(Response.encode(message).finish());
+})
+.catch(err => console.error(err));

linters/node/gnostic-lint-responses/package.json

@@ -0,0 +1,18 @@
+{
+  "name": "gnostic-lint-responses",
+  "version": "1.0.0",
+  "description": "Gnostic linter plugin to check responses",
+  "main": "gnostic-lint-responses.js",
+  "dependencies": {
+    "get-stdin": "^5.0.1",
+    "lodash": "^4.17.5",
+    "nexe": "^2.0.0-rc.24",
+    "protobufjs": "^6.8.4"
+  },
+  "devDependencies": {},
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "",
+  "license": "ISC"
+}