feat: recursively merge package.json scripts field from build configuration (#1372)

Author: kuhe

private/smithy-rpcv2-cbor/package.json

@@ -9,7 +9,8 @@
     "build:types": "tsc -p tsconfig.types.json",
     "build:types:downlevel": "downlevel-dts dist-types dist-types/ts3.4",
     "clean": "rimraf ./dist-* && rimraf *.tsbuildinfo || exit 0",
-    "prepack": "yarn run clean && yarn run build"
+    "prepack": "yarn run clean && yarn run build",
+    "merged": "echo \"this is merged from user configuration.\""
   },
   "main": "./dist-cjs/index.js",
   "types": "./dist-types/index.d.ts",

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/PackageJsonGenerator.java

@@ -43,9 +43,19 @@ static void writePackageJson(
     ) {
         // Write the package.json file.
         InputStream resource = PackageJsonGenerator.class.getResourceAsStream("base-package.json");
-        ObjectNode node = Node.parse(IoUtils.toUtf8String(resource))
-                        .expectObjectNode()
-                        .merge(settings.getPackageJson());
+
+        ObjectNode userSuppliedPackageJson = settings.getPackageJson();
+        ObjectNode defaultPackageJson = Node.parse(IoUtils.toUtf8String(resource))
+            .expectObjectNode();
+
+        ObjectNode mergedScripts = defaultPackageJson.expectObjectMember("scripts")
+            .merge(
+                userSuppliedPackageJson.getObjectMember("scripts")
+                    .orElse(ObjectNode.builder().build())
+            );
+
+        ObjectNode node = defaultPackageJson.merge(userSuppliedPackageJson)
+            .withMember("scripts", mergedScripts);
 
         // Merge TypeScript dependencies into the package.json file.
         for (Map.Entry<String, Map<String, SymbolDependency>> depEntry : dependencies.entrySet()) {

smithy-typescript-protocol-test-codegen/smithy-build.json

@@ -19,6 +19,9 @@
               "name": "Smithy team",
               "url": "https://smithy.io/"
             },
+            "scripts": {
+              "merged": "echo \"this is merged from user configuration.\""
+            },
             "license": "Apache-2.0"
           },
           "private": true,