Add a type for the getCommand function in localize

rictic · rictic · commit cdc98e875b2a · 2022-09-28T11:25:40.000-07:00
This is adding some more circularity than we've had in the past. I'm not sure whether or not it's going to work in CI
diff --git a/package-lock.json b/package-lock.json
diff --git a/packages/labs/cli-localize/package.json b/packages/labs/cli-localize/package.json
@@ -63,7 +63,8 @@
     "@lit/localize-tools": "^0.6.3"
   },
   "devDependencies": {
-    "typescript": "~4.6.2"
+    "typescript": "~4.6.2",
+    "@lit-labs/cli": "^0.1.0"
   },
   "engines": {
     "node": ">=14.8.0"
diff --git a/packages/labs/cli-localize/src/index.ts b/packages/labs/cli-localize/src/index.ts
@@ -3,11 +3,11 @@
  * Copyright 2022 Google LLC
  * SPDX-License-Identifier: BSD-3-Clause
  */
-
+import type {GetCommandFunction} from '@lit-labs/cli/lib/command';
 /**
  * Defines our interface within the Lit CLI.
  */
-export const getCommand = () => {
+export const getCommand: GetCommandFunction = () => {
   return {
     kind: 'resolved',
     name: 'localize',
diff --git a/packages/labs/cli/src/lib/command.ts b/packages/labs/cli/src/lib/command.ts
@@ -119,7 +119,7 @@ export interface CommandModule {
    * strategy, the CLI can offer to install the referenced command if
    * necessary, and we can reuse the error handling code in the CLI core.
    */
-  getCommand(opts: GetCommandsOptions): Command | Promise<Command>;
+  getCommand: GetCommandFunction;
 }
 
 /**
@@ -134,14 +134,31 @@ export interface GetCommandsOptions {
   requestedCommand?: string;
 }
 
+/**
+ * The type of the getCommand function in a command module.
+ *
+ * Note that this can return a ReferenceToCommand, which the CLI will
+ * further resolve.
+ *
+ * If your module is deferring to another in a different npm package, it's
+ * generally preferable to return a ReferenceToCommand rather than doing the
+ * dynamic import yourself. That way we use a consistent module resolution
+ * strategy, the CLI can offer to install the referenced command if
+ * necessary, and we can reuse the error handling code in the CLI core.
+ */
+export interface GetCommandFunction {
+  (opts: GetCommandsOptions):
+    | undefined
+    | Command
+    | Promise<Partial<Command> | undefined>;
+}
+
 /**
  * Like CommandModule, only we're not certain that the module obeys the
  * contract correctly.
  *
  * This is the type we should use internally when loading a module.
  */
 export interface MaybeCommandModule {
-  getCommand?(
-    opts: GetCommandsOptions
-  ): undefined | Command | Promise<Partial<Command> | undefined>;
+  getCommand?: GetCommandFunction;
 }
