feat(wasm-utxo): expose testutils as a submodule

Add a new export for testutils in package.json to allow other modules to
import helper functions and test fixtures.

Issue: BTC-2866

Co-authored-by: llm-git <llm-git@ttll.de>

Author: OttoAllmendinger

packages/wasm-utxo/js/index.ts

@@ -16,8 +16,6 @@ export * as fixedScriptWallet from "./fixedScriptWallet/index.js";
 export * as descriptorWallet from "./descriptorWallet/index.js";
 export * as bip32 from "./bip32.js";
 export * as ecpair from "./ecpair.js";
-export * as testutils from "./testutils/index.js";
-
 // Only the most commonly used classes and types are exported at the top level for convenience
 export { ECPair } from "./ecpair.js";
 export { BIP32 } from "./bip32.js";

packages/wasm-utxo/package.json

@@ -23,6 +23,16 @@
         "types": "./dist/cjs/js/index.d.ts",
         "default": "./dist/cjs/js/index.js"
       }
+    },
+    "./testutils": {
+      "import": {
+        "types": "./dist/esm/js/testutils/index.d.ts",
+        "default": "./dist/esm/js/testutils/index.js"
+      },
+      "require": {
+        "types": "./dist/cjs/js/testutils/index.d.ts",
+        "default": "./dist/cjs/js/testutils/index.js"
+      }
     }
   },
   "main": "./dist/cjs/js/index.js",