BuildPlugin: fix build.watch_dir to allow passing in array (#557)

* Add failing test for build.watch_dir as array

* Support passing in array of strings to build.watch_dir

Author: sj-e2digital

packages/core/src/plugins/build.ts

@@ -41,7 +41,13 @@ export class BuildPlugin extends Plugin<BuildOptions> implements BuildOptions {
     description: "Directory to watch for rebuilding on changes",
     fromWrangler: ({ build, miniflare }) => {
       const watchPaths = miniflare?.build_watch_dirs ?? [];
-      if (build?.watch_dir) watchPaths.push(build.watch_dir);
+      if (build?.watch_dir) {
+        watchPaths.push(
+          ...(Array.isArray(build.watch_dir)
+            ? build.watch_dir
+            : [build.watch_dir])
+        );
+      }
       if (watchPaths.length) return watchPaths;
 
       // If build command set and no paths set, fallback to watching "src"

packages/core/test/plugins/build.spec.ts

@@ -98,6 +98,18 @@ test("BuildPlugin: parses options from wrangler config", (t) => {
     buildBasePath: undefined,
     buildWatchPaths: undefined,
   });
+  // build.watch_dir should accept an array of strings
+  options = parsePluginWranglerConfig(BuildPlugin, {
+    build: {
+      watch_dir: ["source", "source1"],
+    },
+    miniflare: {
+      build_watch_dirs: ["source2", "source3"],
+    },
+  });
+  t.like(options, {
+    buildWatchPaths: ["source2", "source3", "source", "source1"],
+  });
 });
 test("BuildPlugin: logs options", (t) => {
   const logs = logPluginOptions(BuildPlugin, {

packages/shared/src/wrangler.ts

@@ -124,7 +124,7 @@ export interface WranglerConfig extends WranglerEnvironmentConfig {
   build?: {
     command?: string;
     cwd?: string;
-    watch_dir?: string;
+    watch_dir?: string | string[];
     upload?: {
       format?: "service-worker" | "modules";
       dir?: string;