util: support inspecting namespaces of unevaluated modules

Author: devsnek

lib/util.js

@@ -638,6 +638,9 @@ function formatValue(ctx, value, recurseTimes, ln) {
       } else {
         extra = '[items unknown]';
       }
+    } else if (types.isModuleNamespaceObject(value)) {
+      braces[0] = `[${tag}] {`;
+      formatter = formatNamespaceObject;
     } else {
       // Check boxed primitives other than string with valueOf()
       // NOTE: `Date` has to be checked first!
@@ -766,6 +769,15 @@ function formatObject(ctx, value, recurseTimes, keys) {
   return output;
 }
 
+function formatNamespaceObject(ctx, value, recurseTimes, keys) {
+  const len = keys.length;
+  const output = new Array(len);
+  for (var i = 0; i < len; i++) {
+    output[i] = formatNamespaceProperty(ctx, value, recurseTimes, keys[i]);
+  }
+  return output;
+}
+
 // The array is sparse and/or has extra keys
 function formatSpecialArray(ctx, value, recurseTimes, keys, maxLength, valLen) {
   const output = [];
@@ -993,8 +1005,36 @@ function formatPromise(ctx, value, recurseTimes, keys) {
   return output;
 }
 
+function formatKey(ctx, key, enumerable) {
+  if (typeof key === 'symbol') {
+    return `[${ctx.stylize(key.toString(), 'symbol')}]`;
+  }
+  if (enumerable === false) {
+    return `[${key}]`;
+  }
+  if (keyStrRegExp.test(key)) {
+    return ctx.stylize(key, 'name');
+  }
+  return ctx.stylize(strEscape(key), 'string');
+}
+
+function formatNamespaceProperty(ctx, ns, recurseTimes, key) {
+  let value;
+  try {
+    value = formatValue(ctx, ns[key], recurseTimes, true);
+  } catch (err) {
+    if (err instanceof ReferenceError) {
+      value = ctx.stylize('<uninitialized>', 'special');
+    } else {
+      throw err;
+    }
+  }
+
+  return `${formatKey(ctx, key)}: ${value}`;
+}
+
 function formatProperty(ctx, value, recurseTimes, key, array) {
-  let name, str;
+  let str;
   const desc = Object.getOwnPropertyDescriptor(value, key) ||
     { value: value[key], enumerable: true };
   if (desc.value !== undefined) {
@@ -1016,17 +1056,8 @@ function formatProperty(ctx, value, recurseTimes, key, array) {
   if (array === 1) {
     return str;
   }
-  if (typeof key === 'symbol') {
-    name = `[${ctx.stylize(key.toString(), 'symbol')}]`;
-  } else if (desc.enumerable === false) {
-    name = `[${key}]`;
-  } else if (keyStrRegExp.test(key)) {
-    name = ctx.stylize(key, 'name');
-  } else {
-    name = ctx.stylize(strEscape(key), 'string');
-  }
 
-  return `${name}: ${str}`;
+  return `${formatKey(ctx, key, desc.enumerable)}: ${str}`;
 }
 
 function reduceToSingleString(ctx, output, base, braces, addLn) {

test/parallel/test-util-inspect-namespace.js

@@ -0,0 +1,22 @@
+'use strict';
+
+// Flags: --experimental-vm-modules
+
+const common = require('../common');
+const assert = require('assert');
+
+common.crashOnUnhandledRejection();
+
+const { Module } = require('vm');
+const { inspect } = require('util');
+
+(async () => {
+  const m = new Module('export const a = 1; export var b = 2');
+  await m.link(() => 0);
+  m.instantiate();
+  assert.strictEqual(
+    inspect(m.namespace),
+    '[Module] { a: <uninitialized>, b: undefined }');
+  await m.evaluate();
+  assert.strictEqual(inspect(m.namespace), '[Module] { a: 1, b: 2 }');
+})();