diff --git a/.eslintrc.js b/.eslintrc.js
index fae91f82b5c0..2d7860758b68 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -190,7 +190,6 @@ module.exports = {
         // investigation or different solutions. They are also likely to be
         // a reasonable size.
         "dom/indexedDB/**",
-        "dom/localstorage/**",
       ],
       rules: {
         // No declaring variables that are never used
diff --git a/dom/localstorage/test/helpers.js b/dom/localstorage/test/helpers.js
index 69281b09df9c..d66804234350 100644
--- a/dom/localstorage/test/helpers.js
+++ b/dom/localstorage/test/helpers.js
@@ -38,17 +38,9 @@ if (!window.runTest) {
 
     await requestFinished(clearAllDatabases());
 
-    ok(typeof testSteps === "function", "There should be a testSteps function");
-    ok(
-      testSteps.constructor.name === "AsyncFunction",
-      "testSteps should be an async function"
-    );
-
     SimpleTest.registerCleanupFunction(async function() {
       await requestFinished(clearAllDatabases());
     });
-
-    add_task(testSteps);
   };
 }
 
diff --git a/dom/localstorage/test/unit/head.js b/dom/localstorage/test/unit/head.js
index 0e0cc10f5413..eaca1ed17372 100644
--- a/dom/localstorage/test/unit/head.js
+++ b/dom/localstorage/test/unit/head.js
@@ -16,36 +16,15 @@ function ok(cond, msg) {
   Assert.ok(!!cond, msg);
 }
 
-function run_test() {
-  runTest();
-}
+add_setup(function() {
+  do_get_profile();
 
-if (!this.runTest) {
-  this.runTest = function() {
-    do_get_profile();
+  enableTesting();
 
-    enableTesting();
+  Cu.importGlobalProperties(["crypto"]);
 
-    Cu.importGlobalProperties(["crypto"]);
-
-    Assert.ok(
-      typeof testSteps === "function",
-      "There should be a testSteps function"
-    );
-    Assert.ok(
-      testSteps.constructor.name === "AsyncFunction",
-      "testSteps should be an async function"
-    );
-
-    registerCleanupFunction(resetTesting);
-
-    add_task(testSteps);
-
-    // Since we defined run_test, we must invoke run_next_test() to start the
-    // async test.
-    run_next_test();
-  };
-}
+  registerCleanupFunction(resetTesting);
+});
 
 function returnToEventLoop() {
   return new Promise(function(resolve) {
diff --git a/dom/localstorage/test/unit/test_archive.js b/dom/localstorage/test/unit/test_archive.js
index 99ac253319f8..51af78db1b24 100644
--- a/dom/localstorage/test/unit/test_archive.js
+++ b/dom/localstorage/test/unit/test_archive.js
@@ -3,7 +3,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const lsArchiveFile = "storage/ls-archive.sqlite";
 
   const principalInfo = {
@@ -75,4 +75,4 @@ async function testSteps() {
   ok(fileSize > 0, "archive file size is greater than zero");
 
   checkStorage();
-}
+});
diff --git a/dom/localstorage/test/unit/test_clientValidation.js b/dom/localstorage/test/unit/test_clientValidation.js
index 57c8f0e822d4..26dc2bfdf719 100644
--- a/dom/localstorage/test/unit/test_clientValidation.js
+++ b/dom/localstorage/test/unit/test_clientValidation.js
@@ -8,7 +8,7 @@
  * We turn on client validation for LocalStorage and ensure that we don't have
  * access to LocalStorage.
  */
-async function testSteps() {
+add_task(async function testSteps() {
   const principal = getPrincipal("http://example.com");
 
   info("Setting prefs");
@@ -29,4 +29,4 @@ async function testSteps() {
     is(ex.name, "NS_ERROR_FAILURE", "Threw right Exception");
     is(ex.result, Cr.NS_ERROR_FAILURE, "Threw with right result");
   }
-}
+});
diff --git a/dom/localstorage/test/unit/test_corruptedDatabase.js b/dom/localstorage/test/unit/test_corruptedDatabase.js
index 61698082fd70..da73bb92f630 100644
--- a/dom/localstorage/test/unit/test_corruptedDatabase.js
+++ b/dom/localstorage/test/unit/test_corruptedDatabase.js
@@ -36,7 +36,7 @@ async function doTest(profile) {
   is(request.result.usage, 0, "Correct usage");
 }
 
-async function testSteps() {
+add_task(async function testSteps() {
   info("Setting pref");
 
   Services.prefs.setBoolPref(
@@ -70,4 +70,4 @@ async function testSteps() {
   for (const profile of profiles) {
     await doTest(profile);
   }
-}
+});
diff --git a/dom/localstorage/test/unit/test_databaseShadowing1.js b/dom/localstorage/test/unit/test_databaseShadowing1.js
index 12c4a646e455..8582f434fc0f 100644
--- a/dom/localstorage/test/unit/test_databaseShadowing1.js
+++ b/dom/localstorage/test/unit/test_databaseShadowing1.js
@@ -6,7 +6,7 @@
 /* import-globals-from databaseShadowing-shared.js */
 loadSubscript("databaseShadowing-shared.js");
 
-async function testSteps() {
+add_task(async function testSteps() {
   enableNextGenLocalStorage();
 
   storeData();
@@ -20,4 +20,4 @@ async function testSteps() {
   exportShadowDatabase("shadowdb.sqlite");
 
   // The shadow database is now prepared for test_databaseShadowing2.js
-}
+});
diff --git a/dom/localstorage/test/unit/test_databaseShadowing2.js b/dom/localstorage/test/unit/test_databaseShadowing2.js
index 924564ad1150..f7b0ddb1a2c2 100644
--- a/dom/localstorage/test/unit/test_databaseShadowing2.js
+++ b/dom/localstorage/test/unit/test_databaseShadowing2.js
@@ -6,7 +6,7 @@
 /* import-globals-from databaseShadowing-shared.js */
 loadSubscript("databaseShadowing-shared.js");
 
-async function testSteps() {
+add_task(async function testSteps() {
   // The shadow database was prepared in test_databaseShadowing1.js
 
   disableNextGenLocalStorage();
@@ -14,4 +14,4 @@ async function testSteps() {
   ok(importShadowDatabase("shadowdb.sqlite"), "Import succeeded");
 
   verifyData([], /* migrated */ true);
-}
+});
diff --git a/dom/localstorage/test/unit/test_databaseShadowing_clearOrigin1.js b/dom/localstorage/test/unit/test_databaseShadowing_clearOrigin1.js
index ed05108af741..d88fde52e5da 100644
--- a/dom/localstorage/test/unit/test_databaseShadowing_clearOrigin1.js
+++ b/dom/localstorage/test/unit/test_databaseShadowing_clearOrigin1.js
@@ -6,7 +6,7 @@
 /* import-globals-from databaseShadowing-shared.js */
 loadSubscript("databaseShadowing-shared.js");
 
-async function testSteps() {
+add_task(async function testSteps() {
   enableNextGenLocalStorage();
 
   storeData();
@@ -27,4 +27,4 @@ async function testSteps() {
 
   // The shadow database is now prepared for
   // test_databaseShadowing_clearOrigin2.js
-}
+});
diff --git a/dom/localstorage/test/unit/test_databaseShadowing_clearOrigin2.js b/dom/localstorage/test/unit/test_databaseShadowing_clearOrigin2.js
index 3c67722ae722..83d792b496eb 100644
--- a/dom/localstorage/test/unit/test_databaseShadowing_clearOrigin2.js
+++ b/dom/localstorage/test/unit/test_databaseShadowing_clearOrigin2.js
@@ -6,7 +6,7 @@
 /* import-globals-from databaseShadowing-shared.js */
 loadSubscript("databaseShadowing-shared.js");
 
-async function testSteps() {
+add_task(async function testSteps() {
   // The shadow database was prepared in test_databaseShadowing_clearOrigin1.js
 
   disableNextGenLocalStorage();
@@ -14,4 +14,4 @@ async function testSteps() {
   ok(importShadowDatabase("shadowdb-clearedOrigin.sqlite"), "Import succeeded");
 
   verifyData([1], /* migrated */ true);
-}
+});
diff --git a/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPattern1.js b/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPattern1.js
index 961da5aaf766..70367bbeff90 100644
--- a/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPattern1.js
+++ b/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPattern1.js
@@ -6,7 +6,7 @@
 /* import-globals-from databaseShadowing-shared.js */
 loadSubscript("databaseShadowing-shared.js");
 
-async function testSteps() {
+add_task(async function testSteps() {
   enableNextGenLocalStorage();
 
   storeData();
@@ -26,4 +26,4 @@ async function testSteps() {
 
   // The shadow database is now prepared for
   // test_databaseShadowing_clearOriginsByPattern2.js
-}
+});
diff --git a/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPattern2.js b/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPattern2.js
index ae4b8959bc66..6c4d794d04f0 100644
--- a/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPattern2.js
+++ b/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPattern2.js
@@ -6,7 +6,7 @@
 /* import-globals-from databaseShadowing-shared.js */
 loadSubscript("databaseShadowing-shared.js");
 
-async function testSteps() {
+add_task(async function testSteps() {
   // The shadow database was prepared in
   // test_databaseShadowing_clearOriginsByPattern1.js
 
@@ -18,4 +18,4 @@ async function testSteps() {
   );
 
   verifyData([4, 5, 6], /* migrated */ true);
-}
+});
diff --git a/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPrefix1.js b/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPrefix1.js
index 6680fda93758..2b605e953fad 100644
--- a/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPrefix1.js
+++ b/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPrefix1.js
@@ -6,7 +6,7 @@
 /* import-globals-from databaseShadowing-shared.js */
 loadSubscript("databaseShadowing-shared.js");
 
-async function testSteps() {
+add_task(async function testSteps() {
   enableNextGenLocalStorage();
 
   storeData();
@@ -25,4 +25,4 @@ async function testSteps() {
 
   // The shadow database is now prepared for
   // test_databaseShadowing_clearOriginsByPrefix2.js
-}
+});
diff --git a/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPrefix2.js b/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPrefix2.js
index 0bea6f039498..892a470723da 100644
--- a/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPrefix2.js
+++ b/dom/localstorage/test/unit/test_databaseShadowing_clearOriginsByPrefix2.js
@@ -6,7 +6,7 @@
 /* import-globals-from databaseShadowing-shared.js */
 loadSubscript("databaseShadowing-shared.js");
 
-async function testSteps() {
+add_task(async function testSteps() {
   // The shadow database was prepared in
   // test_databaseShadowing_clearOriginsByPrefix1.js
 
@@ -18,4 +18,4 @@ async function testSteps() {
   );
 
   verifyData([2, 3], /* migrated */ true);
-}
+});
diff --git a/dom/localstorage/test/unit/test_eviction.js b/dom/localstorage/test/unit/test_eviction.js
index 9c49e1b393a1..2a69b3e71698 100644
--- a/dom/localstorage/test/unit/test_eviction.js
+++ b/dom/localstorage/test/unit/test_eviction.js
@@ -3,7 +3,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const globalLimitKB = 5 * 1024;
 
   const data = {};
@@ -88,4 +88,4 @@ async function testSteps() {
   await requestFinished(request);
 
   is(request.result.usage, 0, "Zero usage");
-}
+});
diff --git a/dom/localstorage/test/unit/test_flushing.js b/dom/localstorage/test/unit/test_flushing.js
index 2f7d63172238..b33ef7c0995b 100644
--- a/dom/localstorage/test/unit/test_flushing.js
+++ b/dom/localstorage/test/unit/test_flushing.js
@@ -9,7 +9,7 @@
  * database in the event of early return due to error. See bug 1559029.
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const principal1 = getPrincipal("http://example1.com");
 
   const usageFile1 = getRelativeFile(
@@ -69,4 +69,4 @@ async function testSteps() {
   // Wait for all database connections to close.
   let request = reset();
   await requestFinished(request);
-}
+});
diff --git a/dom/localstorage/test/unit/test_groupLimit.js b/dom/localstorage/test/unit/test_groupLimit.js
index 1921622b7285..575b7b7b63f2 100644
--- a/dom/localstorage/test/unit/test_groupLimit.js
+++ b/dom/localstorage/test/unit/test_groupLimit.js
@@ -3,7 +3,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const groupLimitKB = 10 * 1024;
 
   const globalLimitKB = groupLimitKB * 5;
@@ -82,4 +82,4 @@ async function testSteps() {
   for (let i = 0; i < urls.length; i++) {
     storages[i].setItem("B", "");
   }
-}
+});
diff --git a/dom/localstorage/test/unit/test_groupMismatch.js b/dom/localstorage/test/unit/test_groupMismatch.js
index ba0fe6f6ade2..46533aa2f72e 100644
--- a/dom/localstorage/test/unit/test_groupMismatch.js
+++ b/dom/localstorage/test/unit/test_groupMismatch.js
@@ -9,7 +9,7 @@
  * quota object. See bug 1516333.
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const principal = getPrincipal("https://foo.bar.mozilla-iot.org");
 
   info("Clearing");
@@ -42,4 +42,4 @@ async function testSteps() {
   info("Adding item");
 
   storage.setItem("foo", "bar");
-}
+});
diff --git a/dom/localstorage/test/unit/test_largeItems.js b/dom/localstorage/test/unit/test_largeItems.js
index c60f6ba3dba6..3ea6bd21b424 100644
--- a/dom/localstorage/test/unit/test_largeItems.js
+++ b/dom/localstorage/test/unit/test_largeItems.js
@@ -10,7 +10,7 @@
  * IPC message size limit would be exceeded, resulting in a crash.
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const globalLimitKB = 5 * 1024;
 
   // 18 and more iterations would produce an IPC message with size greater than
@@ -85,4 +85,4 @@ async function testSteps() {
   await returnToEventLoop();
 
   ok(!storage.hasSnapshot, "Snapshot successfully finished");
-}
+});
diff --git a/dom/localstorage/test/unit/test_lsng_enabled.js b/dom/localstorage/test/unit/test_lsng_enabled.js
index c9b9aa402a1d..d978aaa90136 100644
--- a/dom/localstorage/test/unit/test_lsng_enabled.js
+++ b/dom/localstorage/test/unit/test_lsng_enabled.js
@@ -8,7 +8,6 @@
  * can lead to a data loss in a combination with disabled shadow writes.
  */
 
-// eslint-disable-next-line no-unused-vars
-async function testSteps() {
+add_task(async function testSteps() {
   ok(Services.domStorageManager.nextGenLocalStorageEnabled, "LSNG enabled");
-}
+});
diff --git a/dom/localstorage/test/unit/test_migration.js b/dom/localstorage/test/unit/test_migration.js
index 96dca46162aa..1249eb076fa1 100644
--- a/dom/localstorage/test/unit/test_migration.js
+++ b/dom/localstorage/test/unit/test_migration.js
@@ -3,7 +3,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const principalInfos = [
     { url: "http://localhost", attrs: {} },
     { url: "http://www.mozilla.org", attrs: {} },
@@ -124,4 +124,4 @@ async function testSteps() {
 
     verifyData(clearedOrigins);
   }
-}
+});
diff --git a/dom/localstorage/test/unit/test_migration_emptyValue.js b/dom/localstorage/test/unit/test_migration_emptyValue.js
index a4c752e6ab7c..dd09c82e8836 100644
--- a/dom/localstorage/test/unit/test_migration_emptyValue.js
+++ b/dom/localstorage/test/unit/test_migration_emptyValue.js
@@ -3,8 +3,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-// eslint-disable-next-line no-unused-vars
-async function testSteps() {
+add_task(async function testSteps() {
   const data = {
     key: "foo",
     value: "",
@@ -35,4 +34,4 @@ async function testSteps() {
   info("Verifying data");
 
   is(storage.getItem(data.key), data.value, "Correct value");
-}
+});
diff --git a/dom/localstorage/test/unit/test_old_lsng_pref.js b/dom/localstorage/test/unit/test_old_lsng_pref.js
index 9f814d248379..d502ee8779ea 100644
--- a/dom/localstorage/test/unit/test_old_lsng_pref.js
+++ b/dom/localstorage/test/unit/test_old_lsng_pref.js
@@ -8,11 +8,10 @@
  * implementations has no effect anymore.
  */
 
-// eslint-disable-next-line no-unused-vars
-async function testSteps() {
+add_task(async function testSteps() {
   info("Setting pref");
 
   Services.prefs.setBoolPref("dom.storage.next_gen", false);
 
   ok(Services.domStorageManager.nextGenLocalStorageEnabled, "LSNG enabled");
-}
+});
diff --git a/dom/localstorage/test/unit/test_orderingAfterRemoveAdd.js b/dom/localstorage/test/unit/test_orderingAfterRemoveAdd.js
index d9c1ec914aef..88a2e45d2a13 100644
--- a/dom/localstorage/test/unit/test_orderingAfterRemoveAdd.js
+++ b/dom/localstorage/test/unit/test_orderingAfterRemoveAdd.js
@@ -3,7 +3,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const url = "http://example.com";
 
   info("Setting pref");
@@ -67,4 +67,4 @@ async function testSteps() {
   for (let i = 0; i < keys.length; i++) {
     is(keys[i], savedKeys[i], "Correct key");
   }
-}
+});
diff --git a/dom/localstorage/test/unit/test_originInit.js b/dom/localstorage/test/unit/test_originInit.js
index 05ff37b7a978..48afdf971bd9 100644
--- a/dom/localstorage/test/unit/test_originInit.js
+++ b/dom/localstorage/test/unit/test_originInit.js
@@ -3,7 +3,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const storageDirName = "storage";
   const persistenceTypeDefaultDirName = "default";
   const persistenceTypePersistentDirName = "permanent";
@@ -369,4 +369,4 @@ async function testSteps() {
   ok(exists, "ls directory in permanent origin directory does exist");
 
   await clearPersistentTestOrigin();
-}
+});
diff --git a/dom/localstorage/test/unit/test_preloading.js b/dom/localstorage/test/unit/test_preloading.js
index b1e3393a39a9..977ab10d9974 100644
--- a/dom/localstorage/test/unit/test_preloading.js
+++ b/dom/localstorage/test/unit/test_preloading.js
@@ -3,7 +3,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const principals = [
     getPrincipal("http://example.com", {}),
     getPrincipal("http://example.com", { privateBrowsingId: 1 }),
@@ -81,4 +81,4 @@ async function testSteps() {
       "Data is not preloaded after clearing origin"
     );
   }
-}
+});
diff --git a/dom/localstorage/test/unit/test_schema3upgrade.js b/dom/localstorage/test/unit/test_schema3upgrade.js
index 7a219ec9c4ec..4b851642ea8b 100644
--- a/dom/localstorage/test/unit/test_schema3upgrade.js
+++ b/dom/localstorage/test/unit/test_schema3upgrade.js
@@ -3,7 +3,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const url = "http://example.com";
 
   info("Setting pref");
@@ -36,4 +36,4 @@ async function testSteps() {
 
   let storage = getLocalStorage(getPrincipal(url));
   storage.open();
-}
+});
diff --git a/dom/localstorage/test/unit/test_schema4upgrade.js b/dom/localstorage/test/unit/test_schema4upgrade.js
index 0160bd4c87a2..a6c308af35d9 100644
--- a/dom/localstorage/test/unit/test_schema4upgrade.js
+++ b/dom/localstorage/test/unit/test_schema4upgrade.js
@@ -2,9 +2,8 @@
  * Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
-/* eslint no-unused-vars: ["warn", { "varsIgnorePattern": "(testSteps)" }]*/
 
-async function testSteps() {
+add_task(async function testSteps() {
   const url = "http://example.com";
 
   info("Setting pref");
@@ -37,4 +36,4 @@ async function testSteps() {
 
   let storage = getLocalStorage(getPrincipal(url));
   storage.open();
-}
+});
diff --git a/dom/localstorage/test/unit/test_snapshotting.js b/dom/localstorage/test/unit/test_snapshotting.js
index d29cbf020c98..4b639395f7dd 100644
--- a/dom/localstorage/test/unit/test_snapshotting.js
+++ b/dom/localstorage/test/unit/test_snapshotting.js
@@ -3,7 +3,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const url = "http://example.com";
 
   info("Setting pref");
@@ -327,4 +327,4 @@ async function testSteps() {
       await returnToEventLoop();
     }
   }
-}
+});
diff --git a/dom/localstorage/test/unit/test_stringLength.js b/dom/localstorage/test/unit/test_stringLength.js
index 87ff7d978a6c..52ee59f7d61f 100644
--- a/dom/localstorage/test/unit/test_stringLength.js
+++ b/dom/localstorage/test/unit/test_stringLength.js
@@ -3,7 +3,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const principal = getPrincipal("http://example.org");
 
   const data = {};
@@ -71,4 +71,4 @@ async function testSteps() {
 
   value = storage.getItem(data.secondKey);
   ok(value.length === data.value.length, "Correct string length");
-}
+});
diff --git a/dom/localstorage/test/unit/test_stringLength2.js b/dom/localstorage/test/unit/test_stringLength2.js
index 4c92f21c74ca..f1a1a902cf9d 100644
--- a/dom/localstorage/test/unit/test_stringLength2.js
+++ b/dom/localstorage/test/unit/test_stringLength2.js
@@ -8,7 +8,7 @@
  * database values containing NULs. See bug 1541681.
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const principal = getPrincipal("http://example.org");
 
   const data = {};
@@ -76,4 +76,4 @@ async function testSteps() {
 
   value = storage.getItem(data.secondKey);
   ok(value.length === data.value.length, "Correct string length");
-}
+});
diff --git a/dom/localstorage/test/unit/test_unicodeCharacters.js b/dom/localstorage/test/unit/test_unicodeCharacters.js
index 20bd7072e832..9e48274161f5 100644
--- a/dom/localstorage/test/unit/test_unicodeCharacters.js
+++ b/dom/localstorage/test/unit/test_unicodeCharacters.js
@@ -135,8 +135,7 @@ const fetchFromNewSnapshotNewDatastore = async (itemKey, sample) => {
   });
 };
 
-/* eslint no-unused-vars: ["warn", { "varsIgnorePattern": "(testSteps)" }]*/
-async function testSteps() {
+add_task(async function testSteps() {
   /* This test is based on bug 1681300 */
   Services.prefs.setBoolPref(
     "dom.storage.enable_unsupported_legacy_implementation",
@@ -203,4 +202,4 @@ async function testSteps() {
     "NewSnapshotNewDatastore",
     fetchFromNewSnapshotNewDatastore
   );
-}
+});
diff --git a/dom/localstorage/test/unit/test_uri_encoding_edge_cases.js b/dom/localstorage/test/unit/test_uri_encoding_edge_cases.js
index 2c29616ef606..0da4e8584d80 100644
--- a/dom/localstorage/test/unit/test_uri_encoding_edge_cases.js
+++ b/dom/localstorage/test/unit/test_uri_encoding_edge_cases.js
@@ -11,7 +11,7 @@
  * of a null quota object. See bug 1516333.
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   /**
    * The edge cases are specified in this array of origins. Each edge case must
    * contain two properties uri and path (origin directory path relative to the
@@ -66,4 +66,4 @@ async function testSteps() {
 
     ok(originDir.exists(), `The origin directory ${origin.path} should exist`);
   }
-}
+});
diff --git a/dom/localstorage/test/unit/test_usage.js b/dom/localstorage/test/unit/test_usage.js
index 5424173c1721..552a45e4a67f 100644
--- a/dom/localstorage/test/unit/test_usage.js
+++ b/dom/localstorage/test/unit/test_usage.js
@@ -3,7 +3,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const data = {};
   data.key = "key1";
   data.value = "value1";
@@ -66,4 +66,4 @@ async function testSteps() {
   await requestFinished(request);
 
   is(request.result.usage, 0, "Correct usage");
-}
+});
diff --git a/dom/localstorage/test/unit/test_usageAfterMigration.js b/dom/localstorage/test/unit/test_usageAfterMigration.js
index 840d71d81120..a0bd5efd5b75 100644
--- a/dom/localstorage/test/unit/test_usageAfterMigration.js
+++ b/dom/localstorage/test/unit/test_usageAfterMigration.js
@@ -3,7 +3,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-async function testSteps() {
+add_task(async function testSteps() {
   const principal = getPrincipal("http://example.com");
 
   const dataFile = getRelativeFile(
@@ -161,4 +161,4 @@ async function testSteps() {
   verifyData();
 
   await verifyUsage(/* success */ true);
-}
+});