1 files changed, 72 insertions, 0 deletions
diff --git a/devtools/shared/tests/xpcshell/test_loader.js b/devtools/shared/tests/xpcshell/test_loader.js
new file mode 100644
index 0000000000..195a364bc6
--- /dev/null
+++ b/devtools/shared/tests/xpcshell/test_loader.js
@@ -0,0 +1,72 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const {
+  useDistinctSystemPrincipalLoader,
+  releaseDistinctSystemPrincipalLoader,
+} = ChromeUtils.importESModule(
+  "resource://devtools/shared/loader/DistinctSystemPrincipalLoader.sys.mjs"
+);
+
+function run_test() {
+  const requester = {},
+    requester2 = {};
+
+  const loader = useDistinctSystemPrincipalLoader(requester);
+
+  // The DevTools dedicated global forces invisibleToDebugger on its realm at
+  // https://searchfox.org/mozilla-central/rev/12a18f7e112a4dcf88d8441d439b84144bfbe9a3/js/xpconnect/loader/mozJSModuleLoader.cpp#591-593
+  // but this is not observable directly.
+  const DevToolsSpecialGlobal = Cu.getGlobalForObject(
+    ChromeUtils.importESModule(
+      "resource://devtools/shared/DevToolsInfaillibleUtils.sys.mjs",
+      { loadInDevToolsLoader: true }
+    )
+  );
+
+  const regularLoader = new DevToolsLoader();
+  ok(
+    DevToolsSpecialGlobal !== regularLoader.loader.sharedGlobal,
+    "The regular loader is not using the special DevTools global"
+  );
+
+  info("Assert the key difference with the other regular loaders:");
+  ok(
+    DevToolsSpecialGlobal === loader.loader.sharedGlobal,
+    "The system principal loader is using the special DevTools global"
+  );
+
+  ok(loader.loader, "Loader is not destroyed before calling release");
+
+  info("Now assert the precise behavior of release");
+  releaseDistinctSystemPrincipalLoader({});
+  ok(
+    loader.loader,
+    "Loader is still not destroyed after calling release with another requester"
+  );
+
+  releaseDistinctSystemPrincipalLoader(requester);
+  ok(
+    !loader.loader,
+    "Loader is destroyed after calling release with the right requester"
+  );
+
+  info("Now test the behavior with two concurrent usages");
+  const loader2 = useDistinctSystemPrincipalLoader(requester);
+  Assert.notEqual(loader, loader2, "We get a new loader instance");
+  ok(
+    DevToolsSpecialGlobal === loader2.loader.sharedGlobal,
+    "The new system principal loader is also using the special DevTools global"
+  );
+
+  const loader3 = useDistinctSystemPrincipalLoader(requester2);
+  Assert.equal(loader2, loader3, "The two loader last loaders are shared");
+
+  releaseDistinctSystemPrincipalLoader(requester);
+  ok(loader2.loader, "Loader isn't destroy on the first call to destroy");
+
+  releaseDistinctSystemPrincipalLoader(requester2);
+  ok(!loader2.loader, "Loader is destroyed on the second call to destroy");
+}