--- a/xpcom/tests/unit/head_xpcom.js
+++ b/xpcom/tests/unit/head_xpcom.js
@@ -1,19 +1,22 @@
+let {Constructor: CC, classes: Cc, interfaces: Ci, results: Cr, utils: Cu} = Components;
+
 function get_test_program(prog) {
   var progPath = do_get_cwd();
   progPath.append(prog);
   progPath.leafName = progPath.leafName + mozinfo.bin_suffix;
   return progPath;
 }
 
 function set_process_running_environment() {
   var envSvc = Components.classes["@mozilla.org/process/environment;1"].
     getService(Components.interfaces.nsIEnvironment);
+  // Importing Services here messes up appInfo for some of the tests.
+  // eslint-disable-next-line mozilla/use-services
   var dirSvc = Components.classes["@mozilla.org/file/directory_service;1"].
     getService(Components.interfaces.nsIProperties);
   var greBinDir = dirSvc.get("GreBinD", Components.interfaces.nsIFile);
   envSvc.set("DYLD_LIBRARY_PATH", greBinDir.path);
   // For Linux
   envSvc.set("LD_LIBRARY_PATH", greBinDir.path);
   // XXX: handle windows
 }
-

--- a/xpcom/tests/unit/test_bug121341.js
+++ b/xpcom/tests/unit/test_bug121341.js
@@ -1,10 +1,8 @@
-var Ci = Components.interfaces;
-var Cu = Components.utils;
 Cu.import("resource://gre/modules/NetUtil.jsm");
 
 function run_test() {
   var ios = Components.classes["@mozilla.org/network/io-service;1"].
             getService(Components.interfaces.nsIIOService);
 
   var dataFile = do_get_file("data/bug121341.properties");
   var channel = NetUtil.newChannel({

--- a/xpcom/tests/unit/test_bug325418.js
+++ b/xpcom/tests/unit/test_bug325418.js
@@ -1,11 +1,8 @@
-var Cc = Components.classes;
-var Ci = Components.interfaces;
-
 // 5 seconds.
 const kExpectedDelay1 = 5;
 // 1 second.
 const kExpectedDelay2 = 1;
 
 var gStartTime1;
 var gStartTime2;
 var timer;

--- a/xpcom/tests/unit/test_bug332389.js
+++ b/xpcom/tests/unit/test_bug332389.js
@@ -1,11 +1,8 @@
-var Cc = Components.classes;
-var Ci = Components.interfaces;
-
 function run_test() {
   var f =
       Cc["@mozilla.org/file/directory_service;1"].
       getService(Ci.nsIProperties).get("CurProcD", Ci.nsIFile);
 
   var terminated = false;
   for (var i = 0; i < 100; i++) {
     if (f == null) {

--- a/xpcom/tests/unit/test_bug364285-1.js
+++ b/xpcom/tests/unit/test_bug364285-1.js
@@ -1,11 +1,8 @@
-var Ci = Components.interfaces;
-var Cc = Components.classes;
-
 var nameArray = [
  "ascii",                                           // ASCII
  "fran\u00E7ais",                                   // Latin-1
  "\u0420\u0443\u0441\u0441\u043A\u0438\u0439",      // Cyrillic
  "\u65E5\u672C\u8A9E",                              // Japanese
  "\u4E2D\u6587",                                    // Chinese
  "\uD55C\uAD6D\uC5B4",                              // Korean
  "\uD801\uDC0F\uD801\uDC2D\uD801\uDC3B\uD801\uDC2B" // Deseret

--- a/xpcom/tests/unit/test_bug374754.js
+++ b/xpcom/tests/unit/test_bug374754.js
@@ -1,11 +1,8 @@
-var Cc = Components.classes;
-var Ci = Components.interfaces;
-
 var addedTopic = "xpcom-category-entry-added";
 var removedTopic = "xpcom-category-entry-removed";
 var testCategory = "bug-test-category";
 var testEntry = "@mozilla.org/bug-test-entry;1";
 
 var testValue = "check validity";
 var result = "";
 var expected = "add remove add remove ";

--- a/xpcom/tests/unit/test_bug476919.js
+++ b/xpcom/tests/unit/test_bug476919.js
@@ -1,11 +1,8 @@
-var Cc = Components.classes;
-var Ci = Components.interfaces;
-
 /* global __LOCATION__ */
 
 function run_test() {
   // skip this test on Windows
   if (mozinfo.os != "win") {
     var testDir = __LOCATION__.parent;
     // create a test file, then symlink it, then check that we think it's a symlink
     var targetFile = testDir.clone();

--- a/xpcom/tests/unit/test_bug656331.js
+++ b/xpcom/tests/unit/test_bug656331.js
@@ -1,15 +1,12 @@
 Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
 
 /* global registerAppManifest */
 
-var Cc = Components.classes;
-var Ci = Components.interfaces;
-
 function info(s) {
   dump("TEST-INFO | test_bug656331.js | " + s + "\n");
 }
 
 var gMessageExpected = /Native module.*has version 3.*expected/;
 var gFound = false;
 
 const kConsoleListener = {

--- a/xpcom/tests/unit/test_bug725015.js
+++ b/xpcom/tests/unit/test_bug725015.js
@@ -1,15 +1,12 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var Cc = Components.classes;
-var Ci = Components.interfaces;
-
 Components.utils.import("resource://gre/modules/Services.jsm");
 
 const manifest = do_get_file("bug725015.manifest");
 const contract = "@bug725015.test.contract";
 const observerTopic = "xpcom-category-entry-added";
 const category = "bug725015-test-category";
 const entry = "bug725015-category-entry";
 const cid = Components.ID("{05070380-6e6e-42ba-aaa5-3289fc55ca5a}");

--- a/xpcom/tests/unit/test_debugger_malloc_size_of.js
+++ b/xpcom/tests/unit/test_debugger_malloc_size_of.js
@@ -4,17 +4,16 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // This is just a sanity test that Gecko is giving SpiderMonkey a MallocSizeOf
 // function for new JSRuntimes. There is more extensive testing around the
 // expected byte sizes within SpiderMonkey's jit-tests, we just want to make
 // sure that Gecko is providing SpiderMonkey with the callback it needs.
 
-var Cu = Components.utils;
 const { byteSize } = Cu.getJSTestingFunctions();
 
 function run_test() {
   const objects = [
     {},
     { w: 1, x: 2, y: 3, z: 4, a: 5 },
     [],
     Array(10).fill(null),

--- a/xpcom/tests/unit/test_file_createUnique.js
+++ b/xpcom/tests/unit/test_file_createUnique.js
@@ -1,17 +1,13 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var Cc = Components.classes;
-var Ci = Components.interfaces;
-var Cr = Components.results;
-
 function run_test() {
   // Generate a leaf name that is 255 characters long.
   var longLeafName = new Array(256).join("T");
 
   // Generate the path for a file located in a directory with a long name.
   var tempFile = Cc["@mozilla.org/file/directory_service;1"].
                  getService(Ci.nsIProperties).get("TmpD", Ci.nsIFile);
   tempFile.append(longLeafName);

--- a/xpcom/tests/unit/test_file_equality.js
+++ b/xpcom/tests/unit/test_file_equality.js
@@ -1,18 +1,14 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
 /* vim:set ts=2 sw=2 sts=2 et: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var Cr = Components.results;
-var Ci = Components.interfaces;
-
-var CC = Components.Constructor;
 var LocalFile = CC("@mozilla.org/file/local;1", "nsIFile", "initWithPath");
 
 function run_test() {
   test_normalized_vs_non_normalized();
 }
 
 function test_normalized_vs_non_normalized() {
   // get a directory that exists on all platforms

--- a/xpcom/tests/unit/test_file_renameTo.js
+++ b/xpcom/tests/unit/test_file_renameTo.js
@@ -1,16 +1,13 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var Cc = Components.classes;
-var Ci = Components.interfaces;
-
 function run_test() {
   // Create the base directory.
   let base = Cc["@mozilla.org/file/directory_service;1"]
              .getService(Ci.nsIProperties)
              .get("TmpD", Ci.nsIFile);
   base.append("renameTesting");
   if (base.exists()) {
     base.remove(true);

--- a/xpcom/tests/unit/test_hidden_files.js
+++ b/xpcom/tests/unit/test_hidden_files.js
@@ -1,10 +1,8 @@
-var Ci = Components.interfaces;
-var Cc = Components.classes;
 const NS_OS_TEMP_DIR = "TmpD";
 
 const CWD = do_get_cwd();
 
 var hiddenUnixFile;
 function createUNIXHiddenFile() {
   var dirSvc = Cc["@mozilla.org/file/directory_service;1"].getService(Ci.nsIProperties);
   var tmpDir = dirSvc.get(NS_OS_TEMP_DIR, Ci.nsIFile);
@@ -20,9 +18,8 @@ function createUNIXHiddenFile() {
 function run_test() {
   // Skip this test on Windows
   if (mozinfo.os == "win")
     return;
 
   do_check_true(createUNIXHiddenFile());
   do_check_true(hiddenUnixFile.isHidden());
 }
-

--- a/xpcom/tests/unit/test_home.js
+++ b/xpcom/tests/unit/test_home.js
@@ -1,11 +1,8 @@
-var Ci = Components.interfaces;
-var Cc = Components.classes;
-
 const CWD = do_get_cwd();
 function checkOS(os) {
   const nsILocalFile_ = "nsILocalFile" + os;
   return nsILocalFile_ in Components.interfaces &&
          CWD instanceof Components.interfaces[nsILocalFile_];
 }
 
 const isWin = checkOS("Win");

--- a/xpcom/tests/unit/test_iniProcessor.js
+++ b/xpcom/tests/unit/test_iniProcessor.js
@@ -1,12 +1,8 @@
-var Ci = Components.interfaces;
-var Cc = Components.classes;
-var Cr = Components.results;
-
 var testnum = 0;
 var factory;
 
 function parserForFile(filename) {
     let parser = null;
     try {
         let file = do_get_file(filename);
         do_check_true(!!file);

--- a/xpcom/tests/unit/test_ioutil.js
+++ b/xpcom/tests/unit/test_ioutil.js
@@ -1,17 +1,13 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 4 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var Cc = Components.classes;
-var Ci = Components.interfaces;
-var Cr = Components.results;
-
 const util = Cc["@mozilla.org/io-util;1"].getService(Ci.nsIIOUtil);
 
 function run_test() {
     try {
         util.inputStreamIsBuffered(null);
         do_throw("inputStreamIsBuffered should have thrown");
     } catch (e) {
         do_check_eq(e.result, Cr.NS_ERROR_INVALID_POINTER);

--- a/xpcom/tests/unit/test_localfile.js
+++ b/xpcom/tests/unit/test_localfile.js
@@ -1,18 +1,14 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
 /* vim:set ts=2 sw=2 sts=2 et: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var Cr = Components.results;
-var CC = Components.Constructor;
-var Ci = Components.interfaces;
-
 const MAX_TIME_DIFFERENCE = 2500;
 const MILLIS_PER_DAY      = 1000 * 60 * 60 * 24;
 
 var LocalFile = CC("@mozilla.org/file/local;1", "nsIFile", "initWithPath");
 
 function run_test() {
   test_toplevel_parent_is_null();
   test_normalize_crash_if_media_missing();

--- a/xpcom/tests/unit/test_notxpcom_scriptable.js
+++ b/xpcom/tests/unit/test_notxpcom_scriptable.js
@@ -1,18 +1,13 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var Cc = Components.classes;
-var Ci = Components.interfaces;
-var Cu = Components.utils;
-var Cr = Components.results;
-
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 
 const kCID = Components.ID("{1f9f7181-e6c5-4f4c-8f71-08005cec8468}");
 const kContract = "@testing/notxpcomtest";
 
 function run_test() {
   let manifest = do_get_file("xpcomtest.manifest");
   let registrar = Components.manager.QueryInterface(Ci.nsIComponentRegistrar);
@@ -75,9 +70,8 @@ function run_test() {
   try {
     xpcomObject.QueryInterface(Ci.ScriptableWithNotXPCOMBase);
     ok(false, "Should not have implemented ScriptableWithNotXPCOMBase");
   } catch (e) {
     ok(true, "Should not have implemented ScriptableWithNotXPCOMBase. Correctly threw error: " + e);
   }
   strictEqual(xpcomObject.method3, undefined);
 }
-

--- a/xpcom/tests/unit/test_nsIMutableArray.js
+++ b/xpcom/tests/unit/test_nsIMutableArray.js
@@ -1,17 +1,12 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var Ci = Components.interfaces;
-var Cr = Components.results;
-var Cc = Components.classes;
-var CC = Components.Constructor;
-
 var MutableArray = CC("@mozilla.org/array;1", "nsIMutableArray");
 var SupportsString = CC("@mozilla.org/supports-string;1", "nsISupportsString");
 
 function create_n_element_array(n) {
   var arr = new MutableArray();
   for (let i = 0; i < n; i++) {
     let str = new SupportsString();
     str.data = "element " + i;

--- a/xpcom/tests/unit/test_pipe.js
+++ b/xpcom/tests/unit/test_pipe.js
@@ -1,19 +1,14 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
 /* vim:set ts=2 sw=2 sts=2 et: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var Cc = Components.classes;
-var Ci = Components.interfaces;
-var Cr = Components.results;
-var CC = Components.Constructor;
-
 var Pipe = CC("@mozilla.org/pipe;1", "nsIPipe", "init");
 
 function run_test() {
   test_not_initialized();
   test_ends_are_threadsafe();
 }
 
 function test_not_initialized() {

--- a/xpcom/tests/unit/test_process_directives.js
+++ b/xpcom/tests/unit/test_process_directives.js
@@ -1,11 +1,8 @@
-var Ci = Components.interfaces;
-var Cc = Components.classes;
-
 Components.utils.import("resource://gre/modules/Services.jsm");
 
 function run_test() {
   Components.manager.autoRegister(do_get_file("data/process_directive.manifest"));
 
   let isChild = Services.appinfo.processType == Services.appinfo.PROCESS_TYPE_CONTENT;
 
   if (isChild) {

--- a/xpcom/tests/unit/test_seek_multiplex.js
+++ b/xpcom/tests/unit/test_seek_multiplex.js
@@ -1,17 +1,12 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var Ci = Components.interfaces;
-var Cr = Components.results;
-var CC = Components.Constructor;
-var Cc = Components.classes;
-
 // The string we use as data.
 const data = "0123456789";
 // Number of streams in the multiplex stream.
 const count = 10;
 
 function test_multiplex_streams() {
   var MultiplexStream = CC("@mozilla.org/io/multiplex-input-stream;1",
                            "nsIMultiplexInputStream");
@@ -155,9 +150,8 @@ function test_multiplex_bug797871() {
   seekable.seek(Ci.nsISeekableStream.NS_SEEK_SET, 20);
   do_check_eq(seekable.tell(), 20);
 }
 
 function run_test() {
   test_multiplex_streams();
   test_multiplex_bug797871();
 }
-

--- a/xpcom/tests/unit/test_storagestream.js
+++ b/xpcom/tests/unit/test_storagestream.js
@@ -1,20 +1,16 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
 /* vim:set ts=2 sw=2 sts=2 et: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 /* eslint no-unused-vars: ["error", { "varsIgnorePattern": "unusedVariable" }] */
 
-var Cc = Components.classes;
-var Ci = Components.interfaces;
-var Cr = Components.results;
-
 function run_test() {
   test1();
   test2();
   test3();
   test4();
 }
 
 /**

--- a/xpcom/tests/unit/test_streams.js
+++ b/xpcom/tests/unit/test_streams.js
@@ -1,16 +1,12 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var Ci = Components.interfaces;
-var Cr = Components.results;
-var CC = Components.Constructor;
-
 var Pipe = CC("@mozilla.org/pipe;1",
               "nsIPipe",
               "init");
 var BinaryOutput = CC("@mozilla.org/binaryoutputstream;1",
                       "nsIBinaryOutputStream",
                       "setOutputStream");
 var BinaryInput = CC("@mozilla.org/binaryinputstream;1",
                      "nsIBinaryInputStream",

--- a/xpcom/tests/unit/test_stringstream.js
+++ b/xpcom/tests/unit/test_stringstream.js
@@ -1,17 +1,13 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 4 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var Cc = Components.classes;
-var Ci = Components.interfaces;
-var Cr = Components.results;
-
 function run_test() {
     var s = Cc["@mozilla.org/io/string-input-stream;1"]
               .createInstance(Ci.nsIStringInputStream);
     var body = "This is a test";
     s.setData(body, body.length);
     do_check_eq(s.available(), body.length);
 
     var sis = Cc["@mozilla.org/scriptableinputstream;1"]

--- a/xpcom/tests/unit/test_windows_cmdline_file.js
+++ b/xpcom/tests/unit/test_windows_cmdline_file.js
@@ -1,9 +1,8 @@
-let { classes: Cc, interfaces: Ci, results: Cr, utils: Cu } = Components;
 Cu.import("resource://gre/modules/Services.jsm");
 
 let executableFile = Services.dirsvc.get("CurProcD", Ci.nsIFile);
 executableFile.append("xpcshell.exe");
 function run_test() {
   let quote = '"'; // Windows' cmd processor doesn't actually use single quotes.
   for (let suffix of ["", " -osint", ` --blah "%PROGRAMFILES%"`]) {
     let cmdline = quote + executableFile.path + quote + suffix;

--- a/xpcom/tests/unit/test_windows_registry.js
+++ b/xpcom/tests/unit/test_windows_registry.js
@@ -1,21 +1,15 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
 /* vim:set ts=2 sw=2 sts=2 et: */
 
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-const Cr = Components.results;
-const Ci = Components.interfaces;
-const Cc = Components.classes;
-const Cu = Components.utils;
-const CC = Components.Constructor;
-
 const nsIWindowsRegKey = Ci.nsIWindowsRegKey;
 let regKeyComponent = Cc["@mozilla.org/windows-registry-key;1"];
 
 function run_test() {
     //* create a key structure in a spot that's normally writable (somewhere under HKCU).
     let testKey = regKeyComponent.createInstance(nsIWindowsRegKey);
 
     // If it's already present because a previous test crashed or didn't clean up properly, clean it up first.

--- a/xpcom/tests/unit/test_windows_shortcut.js
+++ b/xpcom/tests/unit/test_windows_shortcut.js
@@ -1,21 +1,15 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
 /* vim:set ts=2 sw=2 sts=2 et: */
 
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var Cr = Components.results;
-var Ci = Components.interfaces;
-var Cc = Components.classes;
-var Cu = Components.utils;
-var CC = Components.Constructor;
-
 const LocalFile = CC("@mozilla.org/file/local;1", "nsIFile", "initWithPath");
 
 Cu.import("resource://gre/modules/Services.jsm");
 
 function run_test() {
   // This test makes sense only on Windows, so skip it on other platforms
   if ("nsILocalFileWin" in Ci
    && do_get_cwd() instanceof Ci.nsILocalFileWin) {