1 files changed, 23 insertions, 0 deletions
diff --git a/js/src/jit-test/lib/nightly-only.js b/js/src/jit-test/lib/nightly-only.js
new file mode 100644
index 0000000000..aad9403b7c
--- /dev/null
+++ b/js/src/jit-test/lib/nightly-only.js
@@ -0,0 +1,23 @@
+// Some experimental features are enabled only on nightly builds, and disabled
+// on beta and release. Tests for these features should not simply disable
+// themselves on all but nightly builds, because if we neglect to update such
+// tests once the features cease to be experimental, we'll silently skip the
+// tests on beta and release, even though they should run.
+
+// Call the function f. On beta and release, expect it to throw an error that is
+// an instance of error.
+function nightlyOnly(error, f) {
+  if (getBuildConfiguration("release_or_beta")) {
+    try {
+      f();
+      throw new Error("use of feature expected to fail on release and beta, but succeeded; please update test");
+    } catch (e) {
+      if (!(e instanceof error)) {
+        throw e;
+      }
+      // All is well.
+    }
+  } else {
+    f();
+  }
+}