Bug 1854214 - Add tests for getRealmConfiguration and getBuildConfiguration r=mgaudet

Differential Revision: https://phabricator.services.mozilla.com/D189037

js/src/jit-test/tests/out-of-tree-apis.js

@@ -0,0 +1,23 @@
+/**
+  * This tests APIs that are relied on by external consumers such as fuzzers,
+  * which could be broken if modified with regard only to in-tree code.
+  */
+
+// getRealmConfiguration and getBuildConfiguration
+// If API changes are planned here, be sure to notify anyone who is fuzzing SM.
+
+config = getRealmConfiguration();
+
+assertEq(typeof config, "object");
+
+for (const [key, value] of Object.entries(config)) {
+  assertEq(getRealmConfiguration(key), value);
+}
+
+config = getBuildConfiguration();
+
+assertEq(typeof config, "object");
+
+for (const [key, value] of Object.entries(config)) {
+  assertEq(getBuildConfiguration(key), value);
+}