Add type for yarnlockfile (#37144)

types/yarnpkg__lockfile/index.d.ts

@@ -0,0 +1,22 @@
+// Type definitions for parse-package-name 1.1
+// Project: https://github.com/yarnpkg/yarn/tree/master/packages/lockfile
+// Definitions by: Eric Wang <https://github.com/fa93hws>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+interface Dependency {
+  [packageName: string]: string;
+}
+
+interface FirstLevelDependency {
+  version: string;
+  resolved?: string;
+  dependencies?: Dependency;
+}
+
+interface LockFileObject {
+  [packageName: string]: FirstLevelDependency;
+}
+
+export = parse;
+
+declare function parse(file: string): { object: LockFileObject };

types/yarnpkg__lockfile/tsconfig.json

@@ -0,0 +1,26 @@
+{
+  "compilerOptions": {
+      "module": "commonjs",
+      "lib": [
+          "es6"
+      ],
+      "noImplicitAny": true,
+      "noImplicitThis": true,
+      "strictNullChecks": true,
+      "strictFunctionTypes": true,
+      "baseUrl": "../",
+      "typeRoots": [
+          "../"
+      ],
+      "types": [],
+      "noEmit": true,
+      "forceConsistentCasingInFileNames": true,
+      "paths": {
+          "@yarnpkg/lockfile": ["yarnpkg__lockfile"]
+      }
+  },
+  "files": [
+      "index.d.ts",
+      "yarnpkg__lockfile-tests.ts"
+  ]
+}

types/yarnpkg__lockfile/tslint.json

@@ -0,0 +1 @@
+{ "extends": "dtslint/dt.json" }

types/yarnpkg__lockfile/yarnpkg__lockfile-tests.ts

@@ -0,0 +1,16 @@
+import parseYarnLock = require('@yarnpkg/lockfile');
+
+function testFirstLevelDependency(obj: {
+  version: string;
+  resolved?: string;
+  dependencies?: {
+    [packageName: string]: string;
+  }
+}) {}
+
+const { object } = parseYarnLock('');
+
+Object.keys(object).forEach(k => {
+  const value = object[k];
+  testFirstLevelDependency(value);
+});