test: increase coverage of internal/util

PR-URL: https://github.com/nodejs/node/pull/10964
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/parallel/test-internal-util-assertCrypto.js

@@ -0,0 +1,12 @@
+// Flags: --expose-internals
+'use strict';
+require('../common');
+const assert = require('assert');
+const util = require('internal/util');
+
+if (!process.versions.openssl) {
+  assert.throws(() => util.assertCrypto(),
+                /^Node.js is not compiled with openssl crypto support$/);
+} else {
+  assert.doesNotThrow(() => util.assertCrypto());
+}

test/parallel/test-internal-util-decorate-error-stack.js

@@ -3,9 +3,13 @@
 const common = require('../common');
 const assert = require('assert');
 const internalUtil = require('internal/util');
+const binding = process.binding('util');
 const spawnSync = require('child_process').spawnSync;
 const path = require('path');
 
+const kArrowMessagePrivateSymbolIndex = binding['arrow_message_private_symbol'];
+const kDecoratedPrivateSymbolIndex = binding['decorated_private_symbol'];
+
 assert.doesNotThrow(function() {
   internalUtil.decorateErrorStack();
   internalUtil.decorateErrorStack(null);
@@ -53,6 +57,19 @@ checkStack(result.stderr);
 
 // Verify that the stack is unchanged when there is no arrow message
 err = new Error('foo');
-const originalStack = err.stack;
+let originalStack = err.stack;
 internalUtil.decorateErrorStack(err);
 assert.strictEqual(originalStack, err.stack);
+
+// Verify that the arrow message is added to the start of the stack when it
+// exists
+const arrowMessage = 'arrow_message';
+err = new Error('foo');
+originalStack = err.stack;
+
+internalUtil.setHiddenValue(err, kArrowMessagePrivateSymbolIndex, arrowMessage);
+internalUtil.decorateErrorStack(err);
+
+assert.strictEqual(err.stack, `${arrowMessage}${originalStack}`);
+assert.strictEqual(internalUtil
+  .getHiddenValue(err, kDecoratedPrivateSymbolIndex), true);