lib: expose setupInstance method on WASI class

lib/wasi.js

@@ -34,15 +34,6 @@ const kBindingName = Symbol('kBindingName');
 
 emitExperimentalWarning('WASI');
 
-
-function setupInstance(self, instance) {
-  validateObject(instance, 'instance');
-  validateObject(instance.exports, 'instance.exports');
-
-  self[kInstance] = instance;
-  self[kSetMemory](instance.exports.memory);
-}
-
 class WASI {
   constructor(options = kEmptyObject) {
     validateObject(options, 'options');
@@ -118,14 +109,25 @@ class WASI {
     this[kInstance] = undefined;
   }
 
-  // Must not export _initialize, must export _start
-  start(instance) {
+  finalizeBindings(instance, {
+    memory = instance?.exports?.memory,
+  } = {}) {
     if (this[kStarted]) {
       throw new ERR_WASI_ALREADY_STARTED();
     }
+
+    validateObject(instance, 'instance');
+    validateObject(instance.exports, 'instance.exports');
+
+    this[kSetMemory](memory);
+
+    this[kInstance] = instance;
     this[kStarted] = true;
+  }
 
-    setupInstance(this, instance);
+  // Must not export _initialize, must export _start
+  start(instance) {
+    this.finalizeBindings(instance);
 
     const { _start, _initialize } = this[kInstance].exports;
 
@@ -145,12 +147,7 @@ class WASI {
 
   // Must not export _start, may optionally export _initialize
   initialize(instance) {
-    if (this[kStarted]) {
-      throw new ERR_WASI_ALREADY_STARTED();
-    }
-    this[kStarted] = true;
-
-    setupInstance(this, instance);
+    this.finalizeBindings(instance);
 
     const { _start, _initialize } = this[kInstance].exports;