[7.x] Utility types (#41246)

.eslintrc.js

@@ -40,6 +40,7 @@ module.exports = {
     {
       files: [
         '.eslintrc.js',
+        'packages/kbn-utility-types/**/*',
         'packages/kbn-eslint-plugin-eslint/**/*',
         'packages/kbn-config-schema/**/*',
         'packages/kbn-pm/**/*',

package.json

@@ -272,6 +272,7 @@
     "@kbn/expect": "1.0.0",
     "@kbn/plugin-generator": "1.0.0",
     "@kbn/test": "1.0.0",
+    "@kbn/utility-types": "1.0.0",
     "@microsoft/api-documenter": "7.2.1",
     "@microsoft/api-extractor": "7.1.8",
     "@octokit/rest": "^15.10.0",

packages/kbn-utility-types/README.md

@@ -0,0 +1,24 @@
+# `@kbn/utility-types`
+
+TypeScript utility types for usage in Kibana.
+
+- This package re-exports a subset of the items in [`utility-types`](https://github.com/piotrwitek/utility-types)
+- You can also add more utility types here.
+
+
+## Usage
+
+```ts
+import { UnwrapPromise } from '@kbn/utility-types';
+
+type A = Promise<string>;
+type B = UnwrapPromise<A>; // string
+```
+
+
+## Reference
+
+- `UnwrapPromise<T>` &mdash; Returns wrapped type of a promise.
+- `UnwrapObservable<T>` &mdash; Returns wrapped type of an observable.
+- `ShallowPromise<T>` &mdash; Same as `Promise` type, but it flat maps the wrapped type.
+- `ObservableLike<T>` &mdash; Minimal interface for an object resembling an `Observable`.

packages/kbn-utility-types/index.ts

@@ -0,0 +1,44 @@
+/*
+ * 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 { PromiseType } from 'utility-types';
+
+/**
+ * Returns wrapped type of a promise.
+ */
+export type UnwrapPromise<T extends Promise<any>> = PromiseType<T>;
+
+/**
+ * Minimal interface for an object resembling an `Observable`.
+ */
+export interface ObservableLike<T> {
+  subscribe(observer: (value: T) => void): void;
+}
+
+/**
+ * Returns wrapped type of an observable.
+ */
+export type UnwrapObservable<T extends ObservableLike<any>> = T extends ObservableLike<infer U>
+  ? U
+  : never;
+
+/**
+ * Converts a type to a `Promise`, unless it is already a `Promise`. Useful when proxying the return value of a possibly async function.
+ */
+export type ShallowPromise<T> = T extends Promise<infer U> ? Promise<U> : Promise<T>;

packages/kbn-utility-types/package.json

@@ -0,0 +1,21 @@
+{
+  "name": "@kbn/utility-types",
+  "version": "1.0.0",
+  "private": true,
+  "license": "Apache-2.0",
+  "main": "target",
+  "types": "target/index.d.ts",
+  "scripts": {
+    "build": "tsc",
+    "kbn:bootstrap": "tsc",
+    "kbn:watch": "tsc --watch",
+    "test": "tsd",
+    "clean": "rimraf target"
+  },
+  "dependencies": {
+    "utility-types": "^3.7.0"
+  },
+  "devDependencies": {
+    "tsd": "^0.7.4"
+  }
+}

packages/kbn-utility-types/test-d/shallow_promise.ts

@@ -0,0 +1,31 @@
+/*
+ * 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 { expectType } from 'tsd';
+import { ShallowPromise } from '../index';
+
+type P1 = ShallowPromise<string>;
+type P2 = ShallowPromise<ShallowPromise<string>>;
+type P3 = ShallowPromise<ShallowPromise<ShallowPromise<string>>>;
+type P4 = ShallowPromise<ShallowPromise<ShallowPromise<number>>>;
+
+expectType<P1>(Promise.resolve<string>('a'));
+expectType<P2>(Promise.resolve<string>('a'));
+expectType<P3>(Promise.resolve<string>('a'));
+expectType<P4>(Promise.resolve<number>(123));

packages/kbn-utility-types/test-d/unwrap_observable.ts

@@ -0,0 +1,25 @@
+/*
+ * 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 { expectType } from 'tsd';
+import { UnwrapObservable, ObservableLike } from '../index';
+
+type STRING = UnwrapObservable<ObservableLike<string>>;
+
+expectType<STRING>('adf');

packages/kbn-utility-types/test-d/unwrap_promise.ts

@@ -0,0 +1,27 @@
+/*
+ * 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 { expectType } from 'tsd';
+import { UnwrapPromise } from '../index';
+
+type STRING = UnwrapPromise<Promise<string>>;
+type TUPLE = UnwrapPromise<Promise<[number, number]>>;
+
+expectType<STRING>('adf');
+expectType<TUPLE>([1, 2]);

packages/kbn-utility-types/tsconfig.json

@@ -0,0 +1,18 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "declaration": true,
+    "declarationDir": "./target",
+    "outDir": "./target",
+    "stripInternal": true,
+    "declarationMap": true,
+    "types": [
+      "jest",
+      "node"
+    ]
+  },
+  "include": ["index.ts", "test-d/**/*"],
+  "exclude": [
+    "target"
+  ]
+}

src/dev/precommit_hook/casing_check_config.js

@@ -42,6 +42,7 @@ export const IGNORE_FILE_GLOBS = [
   '**/{webpackShims,__mocks__}/**/*',
   'x-pack/docs/**/*',
   'src/legacy/ui/public/assets/fonts/**/*',
+  'packages/kbn-utility-types/test-d/**/*',
 
   // Files in this directory must match a pre-determined name in some cases.
   'x-pack/legacy/plugins/canvas/.storybook/*',

src/legacy/server/kbn_server.d.ts

@@ -18,6 +18,7 @@
  */
 
 import { ResponseObject, Server } from 'hapi';
+import { UnwrapPromise } from '@kbn/utility-types';
 
 import { SavedObjectsClientProviderOptions } from 'src/core/server';
 import {
@@ -87,7 +88,7 @@ declare module 'hapi' {
 }
 
 type KbnMixinFunc = (kbnServer: KbnServer, server: Server, config: any) => Promise<any> | void;
-type Unpromise<T> = T extends Promise<infer U> ? U : T;
+
 // eslint-disable-next-line import/no-default-export
 export default class KbnServer {
   public readonly newPlatform: {
@@ -104,7 +105,7 @@ export default class KbnServer {
     };
     stop: null;
     params: {
-      handledConfigPaths: Unpromise<ReturnType<ConfigService['getUsedPaths']>>;
+      handledConfigPaths: UnwrapPromise<ReturnType<ConfigService['getUsedPaths']>>;
     };
   };
   public server: Server;

x-pack/package.json

@@ -33,6 +33,7 @@
     "@kbn/plugin-helpers": "9.0.2",
     "@kbn/pm": "1.0.0",
     "@kbn/test": "1.0.0",
+    "@kbn/utility-types": "1.0.0",
     "@mattapperson/slapshot": "1.2.3",
     "@storybook/addon-actions": "^5.0.5",
     "@storybook/addon-console": "^1.1.0",