Add workspaces to PackageJson type

source/package-json.d.ts

@@ -257,7 +257,39 @@ declare namespace PackageJson {
 		typings?: string;
 	}
 
+	/**
+	An alternative configuration for Yarn workspaces.
+	*/
+	export interface WorkspaceConfig {
+		/**
+		An array of workspace pattern strings which contain the workspace packages.
+		*/
+		packages?: WorkspacePattern[];
+		/**
+		`nohoist` is designed to solve the problem of packages which break when their node_modules are moved to the root workspace directory - a process known as hoisting. For these packages both within your workspace and also some that have been installed via node_modules it is important to have a mechanism for preventing the default yarn workspace behavior. By adding workspace pattern strings here, yarn will resume non-workspace behavior for any packages which matches the pattern (https://classic.yarnpkg.com/blog/2018/02/15/nohoist/).
+		*/
+		nohoist?: WorkspacePattern[];
+	}
+
+	/**
+	A workspace pattern points to a folder or group of folders which contain packages that should be included in the workspace installation process. The patterns are handled with minimatch https://github.com/isaacs/minimatch
+
+	@example
+	`docs` -> Include the docs folder and install it's dependencies.
+	`packages/*` -> Include all nested folders within the packages folder like `packages/cli` and `packages/core`.
+	*/
+	type WorkspacePattern = string;
+
 	export interface YarnConfiguration {
+		/**
+		Used to configure Yarn workspaces (https://classic.yarnpkg.com/docs/workspaces/).
+
+		Workspaces allow you to manage multiple packages within the same repository in such a way that you only need to run `yarn install` once to install all of them in a single pass.
+
+		Please note the top level `private` property of the `package.json` **must** be set to true in order to use workspaces.
+		*/
+		workspaces?: WorkspacePattern[] | WorkspaceConfig;
+
 		/**
 		If your package only allows one version of a given dependency, and you’d like to enforce the same behavior as `yarn install --flat` on the command line, set this to `true`.
 

test-d/package-json.ts

@@ -35,6 +35,7 @@ expectType<PackageJson.Dependency | undefined>(packageJson.peerDependencies);
 expectType<string[] | undefined>(packageJson.bundleDependencies);
 expectType<string[] | undefined>(packageJson.bundledDependencies);
 expectType<PackageJson.Dependency | undefined>(packageJson.resolutions);
+expectType<PackageJson.WorkspaceConfig | string[] | undefined>(packageJson.workspaces);
 expectType<{[engineName: string]: string} | undefined>(packageJson.engines);
 expectType<boolean | undefined>(packageJson.engineStrict);
 expectType<