add test for empty dependencies in package.json

apps/wing/fixtures/valid1/package.json

@@ -6,5 +6,6 @@
   "license": "MIT",
   "files": [
     "**/*.ts"
-  ]
+  ],
+  "dependencies": {}
 }

apps/wing/src/commands/pack.test.ts

@@ -84,6 +84,48 @@ describe("wing pack", () => {
     await expectNoTarball(outdir);
   });
 
+  it("includes empty dependencies in package.json", async () => {
+    // valid1's package.json contains this:
+    // {
+    //   ...
+    //   "dependencies": {}
+    // }
+
+    // GIVEN
+    const projectDir = join(fixturesDir, "valid1");
+    const outdir = await generateTmpDir();
+    process.chdir(projectDir);
+
+    // WHEN
+    await expect(pack({ outFile: join(outdir, "tarball.tgz") })).resolves.not.toThrow();
+
+    // THEN
+    const tarballContents = await extractTarball(join(outdir, "tarball.tgz"), outdir);
+    expect(tarballContents).toBeDefined();
+  });
+
+  it("includes extra files specified by package.json", async () => {
+    // valid1's package.json contains this:
+    // {
+    //   ...
+    //   "files": [
+    //     "**/*.ts"
+    //   ]
+    // }
+
+    // GIVEN
+    const projectDir = join(fixturesDir, "valid1");
+    const outdir = await generateTmpDir();
+    process.chdir(projectDir);
+
+    // WHEN
+    await pack({ outFile: join(outdir, "tarball.tgz") });
+
+    // THEN
+    const tarballContents = await extractTarball(join(outdir, "tarball.tgz"), outdir);
+    expect(tarballContents["util.ts"]).toBeDefined();
+  });
+
   it("includes extra files specified by package.json", async () => {
     // valid1's package.json contains this:
     // {

apps/wing/src/commands/pack.ts

@@ -120,8 +120,8 @@ export async function pack(options: PackageOptions = {}): Promise<string> {
       }
     }
 
-    // check package.json has `dependencies`
-    if (pkgJson.dependencies) {
+    // Check if package.json has non-empty "dependencies"
+    if (pkgJson.dependencies && Object.keys(pkgJson.dependencies).length > 0) {
       throw new Error(
         `Cannot create package with "dependencies" in package.json. Use "peerDependencies" instead.`
       );