Add isConfigSchema typeguard and stop using instanceof Type checks in core (#63821) (#63867)

* add isConfigSchema type guard

* replace instanceof checks with isConfigSchema

* add dummy test plugin using a route with validation schema

* remove `?.` prop access

* remove test plugin

* fix test description

packages/kbn-config-schema/src/index.ts

@@ -60,6 +60,7 @@ import {
 export { ObjectType, TypeOf, Type };
 export { ByteSizeValue } from './byte_size_value';
 export { SchemaTypeError, ValidationError } from './errors';
+export { isConfigSchema } from './typeguards';
 
 function any(options?: TypeOptions<any>) {
   return new AnyType(options);

packages/kbn-config-schema/src/typeguards/index.ts

@@ -0,0 +1,20 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you 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
+ *
+ *    http://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.
+ */
+
+export { isConfigSchema } from './is_config_schema';

packages/kbn-config-schema/src/typeguards/is_config_schema.test.ts

@@ -0,0 +1,56 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you 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
+ *
+ *    http://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.
+ */
+
+import { schema } from '..';
+import { isConfigSchema } from './is_config_schema';
+
+describe('isConfigSchema', () => {
+  it('returns true for every sub classes of `Type`', () => {
+    expect(isConfigSchema(schema.any())).toBe(true);
+    expect(isConfigSchema(schema.arrayOf(schema.string()))).toBe(true);
+    expect(isConfigSchema(schema.boolean())).toBe(true);
+    expect(isConfigSchema(schema.buffer())).toBe(true);
+    expect(isConfigSchema(schema.byteSize())).toBe(true);
+    expect(isConfigSchema(schema.duration())).toBe(true);
+    expect(isConfigSchema(schema.literal(''))).toBe(true);
+    expect(isConfigSchema(schema.mapOf(schema.string(), schema.number()))).toBe(true);
+    expect(isConfigSchema(schema.nullable(schema.string()))).toBe(true);
+    expect(isConfigSchema(schema.number())).toBe(true);
+    expect(isConfigSchema(schema.object({}))).toBe(true);
+    expect(isConfigSchema(schema.oneOf([schema.string()]))).toBe(true);
+    expect(isConfigSchema(schema.recordOf(schema.string(), schema.object({})))).toBe(true);
+    expect(isConfigSchema(schema.string())).toBe(true);
+    expect(isConfigSchema(schema.stream())).toBe(true);
+  });
+
+  it('returns false for every javascript data type', () => {
+    expect(isConfigSchema('foo')).toBe(false);
+    expect(isConfigSchema(42)).toBe(false);
+    expect(isConfigSchema(new Date())).toBe(false);
+    expect(isConfigSchema(null)).toBe(false);
+    expect(isConfigSchema(undefined)).toBe(false);
+    expect(isConfigSchema([1, 2, 3])).toBe(false);
+    expect(isConfigSchema({ foo: 'bar' })).toBe(false);
+    expect(isConfigSchema(function() {})).toBe(false);
+  });
+
+  it('returns true as long as `__isKbnConfigSchemaType` is true', () => {
+    expect(isConfigSchema({ __isKbnConfigSchemaType: true })).toBe(true);
+  });
+});

packages/kbn-config-schema/src/typeguards/is_config_schema.ts

@@ -0,0 +1,24 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you 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
+ *
+ *    http://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.
+ */
+
+import { Type } from '../types';
+
+export function isConfigSchema(obj: any): obj is Type<any> {
+  return obj ? obj.__isKbnConfigSchemaType === true : false;
+}

packages/kbn-config-schema/src/types/type.ts

@@ -32,6 +32,9 @@ export abstract class Type<V> {
   // sets the value to `null` while still keeping the type.
   public readonly type: V = null! as V;
 
+  // used for the `isConfigSchema` typeguard
+  public readonly __isKbnConfigSchemaType = true;
+
   /**
    * Internal "schema" backed by Joi.
    * @type {Schema}

src/core/server/http/router/router.ts

@@ -20,7 +20,7 @@
 import { Request, ResponseObject, ResponseToolkit } from 'hapi';
 import Boom from 'boom';
 
-import { Type } from '@kbn/config-schema';
+import { isConfigSchema } from '@kbn/config-schema';
 import { Logger } from '../../logging';
 import { KibanaRequest } from './request';
 import { KibanaResponseFactory, kibanaResponseFactory, IKibanaResponse } from './response';
@@ -139,7 +139,7 @@ function routeSchemasFromRouteConfig<P, Q, B>(
 
   if (route.validate !== false) {
     Object.entries(route.validate).forEach(([key, schema]) => {
-      if (!(schema instanceof Type || typeof schema === 'function')) {
+      if (!(isConfigSchema(schema) || typeof schema === 'function')) {
         throw new Error(
           `Expected a valid validation logic declared with '@kbn/config-schema' package or a RouteValidationFunction at key: [${key}].`
         );

src/core/server/http/router/validator/validator.ts

@@ -17,7 +17,7 @@
  * under the License.
  */
 
-import { ValidationError, Type, schema, ObjectType } from '@kbn/config-schema';
+import { ValidationError, Type, schema, ObjectType, isConfigSchema } from '@kbn/config-schema';
 import { Stream } from 'stream';
 import { RouteValidationError } from './validator_error';
 
@@ -236,7 +236,7 @@ export class RouteValidator<P = {}, Q = {}, B = {}> {
     data?: unknown,
     namespace?: string
   ): RouteValidationResultType<typeof validationRule> {
-    if (validationRule instanceof Type) {
+    if (isConfigSchema(validationRule)) {
       return validationRule.validate(data, {}, namespace);
     } else if (typeof validationRule === 'function') {
       return this.validateFunction(validationRule, data, namespace);

src/core/server/plugins/plugin.ts

@@ -21,7 +21,7 @@ import { join } from 'path';
 import typeDetect from 'type-detect';
 import { Subject } from 'rxjs';
 import { first } from 'rxjs/operators';
-import { Type } from '@kbn/config-schema';
+import { isConfigSchema } from '@kbn/config-schema';
 
 import { Logger } from '../logging';
 import {
@@ -150,7 +150,7 @@ export class PluginWrapper<
     }
 
     const configDescriptor = pluginDefinition.config;
-    if (!(configDescriptor.schema instanceof Type)) {
+    if (!isConfigSchema(configDescriptor.schema)) {
       throw new Error('Configuration schema expected to be an instance of Type');
     }
     return configDescriptor;