1 files changed, 50 insertions, 0 deletions
diff --git a/toolkit/modules/tests/MockDocument.jsm b/toolkit/modules/tests/MockDocument.jsm
new file mode 100644
index 000000000..3cae9bb91
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+++ b/toolkit/modules/tests/MockDocument.jsm
@@ -0,0 +1,50 @@
+/**
+ * Provides infrastructure for tests that would require mock document.
+ */
+
+"use strict";
+
+this.EXPORTED_SYMBOLS = ["MockDocument"]
+
+const {classes: Cc, interfaces: Ci, utils: Cu, results: Cr} = Components;
+
+Cu.importGlobalProperties(["URL"]);
+
+const MockDocument = {
+  /**
+   * Create a document for the given URL containing the given HTML with the ownerDocument of all <form>s having a mocked location.
+   */
+  createTestDocument(aDocumentURL, aContent = "<form>", aType = "text/html") {
+    let parser = Cc["@mozilla.org/xmlextras/domparser;1"].
+                 createInstance(Ci.nsIDOMParser);
+    parser.init();
+    let parsedDoc = parser.parseFromString(aContent, aType);
+
+    for (let element of parsedDoc.forms) {
+      this.mockOwnerDocumentProperty(element, parsedDoc, aDocumentURL);
+    }
+    return parsedDoc;
+  },
+
+  mockOwnerDocumentProperty(aElement, aDoc, aURL) {
+    // Mock the document.location object so we can unit test without a frame. We use a proxy
+    // instead of just assigning to the property since it's not configurable or writable.
+    let document = new Proxy(aDoc, {
+      get(target, property, receiver) {
+        // document.location is normally null when a document is outside of a "browsing context".
+        // See https://html.spec.whatwg.org/#the-location-interface
+        if (property == "location") {
+          return new URL(aURL);
+        }
+        return target[property];
+      },
+    });
+
+    // Assign element.ownerDocument to the proxy so document.location works.
+    Object.defineProperty(aElement, "ownerDocument", {
+      value: document,
+    });
+  },
+
+};
+