1 files changed, 130 insertions, 0 deletions
diff --git a/tools/lint/eslint/eslint-plugin-mozilla/tests/use-isInstance.js b/tools/lint/eslint/eslint-plugin-mozilla/tests/use-isInstance.js
new file mode 100644
index 0000000000..7e7b423484
--- /dev/null
+++ b/tools/lint/eslint/eslint-plugin-mozilla/tests/use-isInstance.js
@@ -0,0 +1,130 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+var rule = require("../lib/rules/use-isInstance");
+var RuleTester = require("eslint").RuleTester;
+
+const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+
+// ------------------------------------------------------------------------------
+// Tests
+// ------------------------------------------------------------------------------
+
+const errors = [
+  {
+    message:
+      "Please prefer .isInstance() in chrome scripts over the standard instanceof operator for DOM interfaces, " +
+      "since the latter will return false when the object is created from a different context.",
+    type: "BinaryExpression",
+  },
+];
+
+const env = { browser: true };
+
+/**
+ * A test case boilerplate simulating chrome privileged script.
+ * @param {string} code
+ */
+function mockChromeScript(code) {
+  return {
+    code,
+    filename: "foo.sys.mjs",
+    env,
+  };
+}
+
+/**
+ * A test case boilerplate simulating content script.
+ * @param {string} code
+ */
+function mockContentScript(code) {
+  return {
+    code,
+    filename: "foo.js",
+    env,
+  };
+}
+
+ruleTester.run("use-isInstance", rule, {
+  valid: [
+    mockChromeScript("(() => {}) instanceof Function;"),
+    mockChromeScript("({}) instanceof Object;"),
+    mockChromeScript("Node instanceof Object;"),
+    mockChromeScript("node instanceof lazy.Node;"),
+    mockChromeScript("var Node;node instanceof Node;"),
+    mockChromeScript("file instanceof lazy.File;"),
+    mockChromeScript("file instanceof OS.File;"),
+    mockChromeScript("file instanceof OS.File.Error;"),
+    mockChromeScript("file instanceof lazy.OS.File;"),
+    mockChromeScript("file instanceof lazy.OS.File.Error;"),
+    mockChromeScript("file instanceof lazy.lazy.OS.File;"),
+    mockChromeScript("var File;file instanceof File;"),
+    mockChromeScript("foo instanceof RandomGlobalThing;"),
+    mockChromeScript("foo instanceof lazy.RandomGlobalThing;"),
+    mockContentScript("node instanceof Node;"),
+    mockContentScript("file instanceof File;"),
+    mockContentScript(
+      "SpecialPowers.ChromeUtils.import(''); file instanceof File;"
+    ),
+  ],
+  invalid: [
+    {
+      code: "node instanceof Node",
+      output: "Node.isInstance(node)",
+      env,
+      errors,
+      filename: "foo.sys.mjs",
+    },
+    {
+      code: "text instanceof win.Text",
+      output: "win.Text.isInstance(text)",
+      errors,
+      filename: "foo.sys.mjs",
+    },
+    {
+      code: "target instanceof this.contentWindow.HTMLAudioElement",
+      output: "this.contentWindow.HTMLAudioElement.isInstance(target)",
+      errors,
+      filename: "foo.sys.mjs",
+    },
+    {
+      code: "target instanceof File",
+      output: "File.isInstance(target)",
+      env,
+      errors,
+      filename: "foo.sys.mjs",
+    },
+    {
+      code: "target instanceof win.File",
+      output: "win.File.isInstance(target)",
+      errors,
+      filename: "foo.sys.mjs",
+    },
+    {
+      code: "window.arguments[0] instanceof window.XULElement",
+      output: "window.XULElement.isInstance(window.arguments[0])",
+      errors,
+      filename: "foo.sys.mjs",
+    },
+    {
+      code: "ChromeUtils.import(''); node instanceof Node",
+      output: "ChromeUtils.import(''); Node.isInstance(node)",
+      env,
+      errors,
+      filename: "foo.js",
+    },
+    {
+      code: "ChromeUtils.import(''); file instanceof File",
+      output: "ChromeUtils.import(''); File.isInstance(file)",
+      env,
+      errors,
+      filename: "foo.js",
+    },
+  ],
+});