1 files changed, 113 insertions, 0 deletions
diff --git a/js/xpconnect/tests/unit/test_lazyproxy.js b/js/xpconnect/tests/unit/test_lazyproxy.js
new file mode 100644
index 0000000000..2cf90b339d
--- /dev/null
+++ b/js/xpconnect/tests/unit/test_lazyproxy.js
@@ -0,0 +1,113 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * This file tests the method defineLazyProxy from XPCOMUtils.sys.mjs.
+ */
+
+const {XPCOMUtils} = ChromeUtils.importESModule("resource://gre/modules/XPCOMUtils.sys.mjs");
+
+add_task(function test_lazy_proxy() {
+  let tmp = {};
+  let realObject = {
+    "prop1": "value1",
+    "prop2": "value2",
+  };
+
+  let evaluated = false;
+  let untrapCalled = false;
+
+  let lazyProxy = XPCOMUtils.defineLazyProxy(
+    tmp,
+    "myLazyProxy",
+
+    // Initiliazer function
+    function init() {
+      evaluated = true;
+      return realObject;
+    },
+
+    // Stub properties
+    {
+      "prop1": "stub"
+    },
+
+    // Untrap callback
+    function untrapCallback(obj) {
+      Assert.equal(obj, realObject, "The underlying object can be obtained in the untrap callback");
+      untrapCalled = true;
+    }
+  );
+
+  // Check that the proxy returned and the one
+  // defined in tmp are the same.
+  //
+  // Note: Assert.strictEqual can't be used here
+  // because it wants to stringify the two objects
+  // compared, which defeats the lazy proxy.
+  Assert.ok(lazyProxy === tmp.myLazyProxy, "Return value and object defined are the same");
+
+  Assert.ok(Cu.isProxy(lazyProxy), "Returned value is in fact a proxy");
+
+  // Check that just using the proxy above didn't
+  // trigger the lazy getter evaluation.
+  Assert.ok(!evaluated, "The lazy proxy hasn't been evaluated yet");
+  Assert.ok(!untrapCalled, "The untrap callback hasn't been called yet");
+
+  // Accessing a stubbed property returns the stub
+  // value and doesn't trigger evaluation.
+  Assert.equal(lazyProxy.prop1, "stub", "Accessing a stubbed property returns the stubbed value");
+
+  Assert.ok(!evaluated, "The access to the stubbed property above didn't evaluate the lazy proxy");
+  Assert.ok(!untrapCalled, "The untrap callback hasn't been called yet");
+
+  // Now the access to another property will trigger
+  // the evaluation, as expected.
+  Assert.equal(lazyProxy.prop2, "value2", "Property access is correctly forwarded to the underlying object");
+
+  Assert.ok(evaluated, "Accessing a non-stubbed property triggered the proxy evaluation");
+  Assert.ok(untrapCalled, "The untrap callback was called");
+
+  // The value of prop1 is now the real value and not the stub value.
+  Assert.equal(lazyProxy.prop1, "value1", "The  value of prop1 is now the real value and not the stub one");
+});
+
+add_task(function test_module_version() {
+  // Test that passing a string instead of an initialization function
+  // makes this behave like a lazy module getter.
+  const TEST_FILE_URI = "resource://test/TestFile.jsm";
+  let underlyingObject;
+
+  Cu.unload(TEST_FILE_URI);
+
+  let lazyProxy = XPCOMUtils.defineLazyProxy(
+    null,
+    "TestFile",
+    TEST_FILE_URI,
+    null, /* no stubs */
+    function untrapCallback(object) {
+      underlyingObject = object;
+    }
+  );
+
+  Assert.ok(!Cu.isModuleLoaded(TEST_FILE_URI), "The NetUtil module was not loaded by the lazy proxy definition");
+
+  // Access the object, which will evaluate the proxy.
+  lazyProxy.foo = "bar";
+
+  // Module was loaded.
+  Assert.ok(Cu.isModuleLoaded(TEST_FILE_URI), "The NetUtil module was loaded");
+
+  let { TestFile } = ChromeUtils.import(TEST_FILE_URI, {});
+
+  // Avoids a gigantic stringification in the logs.
+  Assert.ok(TestFile === underlyingObject, "The module loaded is the same as the one directly obtained by ChromeUtils.import");
+
+  // Proxy correctly passed the setter to the underlying object.
+  Assert.equal(TestFile.foo, "bar", "Proxy correctly passed the setter to the underlying object");
+
+  delete lazyProxy.foo;
+
+  // Proxy correctly passed the delete operation to the underlying object.
+  Assert.ok(!TestFile.hasOwnProperty("foo"), "Proxy correctly passed the delete operation to the underlying object");
+});