allow any function to report its toString as a NativeFunction

related: https://github.com/tc39/Function-prototype-toString-revision/pull/26

1 files changed, 14 insertions, 0 deletions

diff --git a/harness/nativeFunctionMatcher.js b/harness/nativeFunctionMatcher.js
index 0a2d248a3..52120ea48 100644
--- a/harness/nativeFunctionMatcher.js
+++ b/harness/nativeFunctionMatcher.js
@@ -6,3 +6,17 @@ description: |
     the NativeFunction grammar production without requiring a correct tokeniser.
 ---*/
 const NATIVE_FUNCTION_RE = /\bfunction\b[\s\S]*\([\s\S]*\)[\s\S]*\{[\s\S]*\[[\s\S]*\bnative\b[\s\S]+\bcode\b[\s\S]*\][\s\S]*\}/;
+
+const assertToStringOrNativeFunction = function(fn, expected) {
+  const actual = "" + fn;
+  try {
+    assert.sameValue(actual, expected);
+  } catch (unused) {
+    assertNativeFunction(fn);
+  }
+};
+
+const assertNativeFunction = function(fn) {
+  const actual = "" + fn;
+  assert(NATIVE_FUNCTION_RE.test(actual), "looks pretty much like a NativeFunction");
+};