diff --git a/devtools/client/application/test/browser/browser_application_panel_telemetry-debug-worker.js b/devtools/client/application/test/browser/browser_application_panel_telemetry-debug-worker.js
index fe95dabd5e6d..49f43d47c84d 100644
--- a/devtools/client/application/test/browser/browser_application_panel_telemetry-debug-worker.js
+++ b/devtools/client/application/test/browser/browser_application_panel_telemetry-debug-worker.js
@@ -34,7 +34,11 @@ add_task(async function () {
 
   const events = getTelemetryEvents("jsdebugger");
   const openToolboxEvent = events.find(event => event.method == "enter");
-  ok(openToolboxEvent.session_id > 0, "Event has a valid session id");
+  Assert.greater(
+    Number(openToolboxEvent.session_id),
+    0,
+    "Event has a valid session id"
+  );
   is(
     openToolboxEvent.start_state,
     "application",
diff --git a/devtools/client/application/test/browser/head.js b/devtools/client/application/test/browser/head.js
index 6b7e67ff8d12..265fd44bf0f8 100644
--- a/devtools/client/application/test/browser/head.js
+++ b/devtools/client/application/test/browser/head.js
@@ -82,7 +82,11 @@ function checkTelemetryEvent(expectedEvent, objectName = "application") {
   // assert we only got 1 event with a valid session ID
   is(events.length, 1, "There was only 1 event logged");
   const [event] = events;
-  ok(event.session_id > 0, "There is a valid session_id in the event");
+  Assert.greater(
+    Number(event.session_id),
+    0,
+    "There is a valid session_id in the event"
+  );
 
   // assert expected data
   Assert.deepEqual(event, { ...expectedEvent, session_id: event.session_id });
diff --git a/devtools/client/debugger/test/mochitest/browser_dbg-features-browser-toolbox-source-tree.js b/devtools/client/debugger/test/mochitest/browser_dbg-features-browser-toolbox-source-tree.js
index fa321f5f43a0..539b2736978b 100644
--- a/devtools/client/debugger/test/mochitest/browser_dbg-features-browser-toolbox-source-tree.js
+++ b/devtools/client/debugger/test/mochitest/browser_dbg-features-browser-toolbox-source-tree.js
@@ -56,6 +56,8 @@ add_task(async function testSourceTreeNamesForWebExtensions() {
   });
 
   await ToolboxTask.spawn(null, async () => {
+    // Disable autofixing to `Assert` methods which are not available here.
+    /* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
     try {
       /* global gToolbox */
       // Wait for the debugger to finish loading.
diff --git a/devtools/client/debugger/test/mochitest/shared-head.js b/devtools/client/debugger/test/mochitest/shared-head.js
index 98a2df5e07bb..fb3da5601dc5 100644
--- a/devtools/client/debugger/test/mochitest/shared-head.js
+++ b/devtools/client/debugger/test/mochitest/shared-head.js
@@ -2,6 +2,10 @@
  * 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 file is loaded in a `spawn` context sometimes which doesn't have,
+// `Assert`, so we can't use its comparison functions.
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 /**
  * Helper methods to drive with the debugger during mochitests. This file can be safely
  * required from other panel test files.
diff --git a/devtools/client/framework/test/browser_toolbox_telemetry_activate_splitconsole.js b/devtools/client/framework/test/browser_toolbox_telemetry_activate_splitconsole.js
index cd1a478f5cf7..31c52e432e0d 100644
--- a/devtools/client/framework/test/browser_toolbox_telemetry_activate_splitconsole.js
+++ b/devtools/client/framework/test/browser_toolbox_telemetry_activate_splitconsole.js
@@ -103,6 +103,6 @@ async function checkResults() {
 
     // extras
     is(extra.host, expected.extra.host, "host is correct");
-    ok(extra.width > 0, "width is greater than 0");
+    Assert.greater(Number(extra.width), 0, "width is greater than 0");
   }
 }
diff --git a/devtools/client/framework/test/browser_toolbox_telemetry_enter.js b/devtools/client/framework/test/browser_toolbox_telemetry_enter.js
index 4cb4611a97b9..ac1253ec790b 100644
--- a/devtools/client/framework/test/browser_toolbox_telemetry_enter.js
+++ b/devtools/client/framework/test/browser_toolbox_telemetry_enter.js
@@ -144,7 +144,7 @@ async function checkResults() {
 
     // extras
     is(extra.host, expected.extra.host, "host is correct");
-    ok(extra.width > 0, "width is greater than 0");
+    Assert.greater(Number(extra.width), 0, "width is greater than 0");
     is(extra.start_state, expected.extra.start_state, "start_state is correct");
     is(extra.panel_name, expected.extra.panel_name, "panel_name is correct");
     is(extra.cold, expected.extra.cold, "cold is correct");
diff --git a/devtools/client/framework/test/browser_toolbox_telemetry_exit.js b/devtools/client/framework/test/browser_toolbox_telemetry_exit.js
index 3056b9af8cfe..98f831d6d4bc 100644
--- a/devtools/client/framework/test/browser_toolbox_telemetry_exit.js
+++ b/devtools/client/framework/test/browser_toolbox_telemetry_exit.js
@@ -121,7 +121,7 @@ async function checkResults() {
 
     // extras
     is(extra.host, expected.extra.host, "host is correct");
-    ok(extra.width > 0, "width is greater than 0");
+    Assert.greater(Number(extra.width), 0, "width is greater than 0");
     is(extra.panel_name, expected.extra.panel_name, "panel_name is correct");
     is(extra.next_panel, expected.extra.next_panel, "next_panel is correct");
     is(extra.reason, expected.extra.reason, "reason is correct");
diff --git a/devtools/client/inspector/test/browser_inspector_sidebarstate.js b/devtools/client/inspector/test/browser_inspector_sidebarstate.js
index 396e78c91fb4..6ccc6df6f406 100644
--- a/devtools/client/inspector/test/browser_inspector_sidebarstate.js
+++ b/devtools/client/inspector/test/browser_inspector_sidebarstate.js
@@ -122,8 +122,8 @@ function checkTelemetryResults() {
     const expected = TELEMETRY_DATA[i];
 
     // ignore timestamp
-    ok(timestamp > 0, "timestamp is greater than 0");
-    ok(extra.time_open > 0, "time_open is greater than 0");
+    Assert.greater(timestamp, 0, "timestamp is greater than 0");
+    Assert.greater(Number(extra.time_open), 0, "time_open is greater than 0");
     is(category, expected.category, "category is correct");
     is(method, expected.method, "method is correct");
     is(object, expected.object, "object is correct");
diff --git a/devtools/client/inspector/test/browser_inspector_switch-to-inspector-on-pick.js b/devtools/client/inspector/test/browser_inspector_switch-to-inspector-on-pick.js
index 171f4f8e7f1b..2bcd2e98732d 100644
--- a/devtools/client/inspector/test/browser_inspector_switch-to-inspector-on-pick.js
+++ b/devtools/client/inspector/test/browser_inspector_switch-to-inspector-on-pick.js
@@ -104,7 +104,7 @@ function checkResults() {
     is(method, expected.method, "method is correct");
     is(object, expected.object, "object is correct");
     is(value, null, "value is correct");
-    ok(extra.width > 0, "width is greater than 0");
+    Assert.greater(Number(extra.width), 0, "width is greater than 0");
 
     checkExtra("host", extra, expected);
     checkExtra("start_state", extra, expected);
diff --git a/devtools/client/netmonitor/test/head.js b/devtools/client/netmonitor/test/head.js
index 5ca346696489..aa92b55f7444 100644
--- a/devtools/client/netmonitor/test/head.js
+++ b/devtools/client/netmonitor/test/head.js
@@ -1156,7 +1156,11 @@ function checkTelemetryEvent(expectedEvent, query) {
   is(events.length, 1, "There was only 1 event logged");
 
   const [event] = events;
-  ok(event.session_id > 0, "There is a valid session_id in the logged event");
+  Assert.greater(
+    Number(event.session_id),
+    0,
+    "There is a valid session_id in the logged event"
+  );
 
   const f = e => JSON.stringify(e, null, 2);
   is(
diff --git a/devtools/client/responsive/test/browser/browser_telemetry_activate_rdm.js b/devtools/client/responsive/test/browser/browser_telemetry_activate_rdm.js
index 7c3927fb1104..1ec8e5976deb 100644
--- a/devtools/client/responsive/test/browser/browser_telemetry_activate_rdm.js
+++ b/devtools/client/responsive/test/browser/browser_telemetry_activate_rdm.js
@@ -111,6 +111,6 @@ async function checkResults() {
 
     // extras
     is(extra.host, expected.extra.host, "host is correct");
-    ok(extra.width > 0, "width is greater than 0");
+    Assert.greater(Number(extra.width), 0, "width is greater than 0");
   }
 }
diff --git a/devtools/client/shared/test/browser_tableWidget_basic.js b/devtools/client/shared/test/browser_tableWidget_basic.js
index a8b737b9d045..5cdf67206e0c 100644
--- a/devtools/client/shared/test/browser_tableWidget_basic.js
+++ b/devtools/client/shared/test/browser_tableWidget_basic.js
@@ -1,6 +1,9 @@
 /* Any copyright is dedicated to the Public Domain.
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
+// We test sorting of strings, which Assert.greater/less etc. don't do.
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 // Tests that the table widget api works fine
 
 "use strict";
diff --git a/devtools/client/storage/test/browser_storage_indexeddb_hide_internal_dbs.js b/devtools/client/storage/test/browser_storage_indexeddb_hide_internal_dbs.js
index 35906256b153..fab834ed5267 100644
--- a/devtools/client/storage/test/browser_storage_indexeddb_hide_internal_dbs.js
+++ b/devtools/client/storage/test/browser_storage_indexeddb_hide_internal_dbs.js
@@ -35,6 +35,8 @@ add_task(async function () {
     const browserToolboxDoc = gToolbox.getCurrentPanel().panelWindow.document;
 
     const browserToolboxHosts = getDBHostsInTree(browserToolboxDoc);
+    // In the spawn task, we don't have access to Assert:
+    // eslint-disable-next-line mozilla/no-comparison-or-assignment-inside-ok
     ok(browserToolboxHosts.length > 1, "There are more than 1 indexedDB hosts");
     ok(
       browserToolboxHosts.includes("about:devtools-toolbox"),
diff --git a/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_filters_changed.js b/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_filters_changed.js
index 95ff2e8e5159..eb8d4eeceb7b 100644
--- a/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_filters_changed.js
+++ b/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_filters_changed.js
@@ -57,7 +57,11 @@ function checkTelemetryEvent(expectedEvent) {
   const events = getFiltersChangedEventsExtra();
   is(events.length, 1, "There was only 1 event logged");
   const [event] = events;
-  ok(event.session_id > 0, "There is a valid session_id in the logged event");
+  Assert.greater(
+    Number(event.session_id),
+    0,
+    "There is a valid session_id in the logged event"
+  );
   const f = e => JSON.stringify(e, null, 2);
   is(
     f(event),
diff --git a/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_jump_to_definition.js b/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_jump_to_definition.js
index 07a1d575f51c..2b722947c8e0 100644
--- a/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_jump_to_definition.js
+++ b/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_jump_to_definition.js
@@ -32,7 +32,11 @@ add_task(async function () {
   const events = getJumpToDefinitionEventsExtra();
   is(events.length, 1, "There was 1 event logged");
   const [event] = events;
-  ok(event.session_id > 0, "There is a valid session_id in the logged event");
+  Assert.greater(
+    Number(event.session_id),
+    0,
+    "There is a valid session_id in the logged event"
+  );
 });
 
 function getJumpToDefinitionEventsExtra() {
diff --git a/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_object_expanded.js b/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_object_expanded.js
index 6dc6149295f6..c671d7cd63e9 100644
--- a/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_object_expanded.js
+++ b/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_object_expanded.js
@@ -35,7 +35,11 @@ add_task(async function () {
   let events = getObjectExpandedEventsExtra();
   is(events.length, 1, "There was 1 event logged");
   const [event] = events;
-  ok(event.session_id > 0, "There is a valid session_id in the logged event");
+  Assert.greater(
+    Number(event.session_id),
+    0,
+    "There is a valid session_id in the logged event"
+  );
 
   info("Click on the second arrow icon to expand the prototype node");
   const secondArrowIcon = message.querySelectorAll(".arrow")[1];
diff --git a/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_reverse_search.js b/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_reverse_search.js
index b801f3b89881..8177ff3ffa79 100644
--- a/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_reverse_search.js
+++ b/devtools/client/webconsole/test/browser/browser_webconsole_telemetry_reverse_search.js
@@ -166,6 +166,6 @@ function checkEventTelemetry(expectedData) {
       expected.extra.functionality,
       "'functionality' is correct"
     );
-    ok(extra.session_id > 0, "'session_id' is correct");
+    Assert.greater(Number(extra.session_id), 0, "'session_id' is correct");
   }
 }
diff --git a/devtools/shared/heapsnapshot/tests/xpcshell/Census.sys.mjs b/devtools/shared/heapsnapshot/tests/xpcshell/Census.sys.mjs
index 0e86f8b05500..93f35a83a32a 100644
--- a/devtools/shared/heapsnapshot/tests/xpcshell/Census.sys.mjs
+++ b/devtools/shared/heapsnapshot/tests/xpcshell/Census.sys.mjs
@@ -148,6 +148,7 @@ function ok(val) {
     throw new Error("Census mismatch: expected truthy, got " + val);
   }
 }
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
 
 // Return a walker that checks that the subject census has at least as many
 // items of each category as |basis|.
diff --git a/docshell/test/browser/browser_browsingContext-02.js b/docshell/test/browser/browser_browsingContext-02.js
index 8439b869b069..480e8f549416 100644
--- a/docshell/test/browser/browser_browsingContext-02.js
+++ b/docshell/test/browser/browser_browsingContext-02.js
@@ -178,7 +178,7 @@ add_task(async function () {
           }
 
           let topBrowserId = topBC.browserId;
-          ok(topBrowserId > 0, "Should have a browser ID.");
+          Assert.greater(topBrowserId, 0, "Should have a browser ID.");
           for (let [name, bc] of Object.entries({
             first,
             second,
@@ -193,7 +193,7 @@ add_task(async function () {
             );
           }
 
-          ok(sixth.browserId > 0, "sixth should have a browserId.");
+          Assert.greater(sixth.browserId, 0, "sixth should have a browserId.");
           isnot(
             sixth.browserId,
             topBrowserId,
diff --git a/docshell/test/browser/browser_csp_sandbox_no_script_js_uri.js b/docshell/test/browser/browser_csp_sandbox_no_script_js_uri.js
index d0b92084ec4c..b5ee19c98e4f 100644
--- a/docshell/test/browser/browser_csp_sandbox_no_script_js_uri.js
+++ b/docshell/test/browser/browser_csp_sandbox_no_script_js_uri.js
@@ -20,8 +20,9 @@ add_task(async function test_csp_sandbox_no_script_js_uri() {
       let observerPromise = SpecialPowers.spawn(browser, [], () => {
         return new Promise(resolve => {
           SpecialPowers.addObserver(function obs(subject) {
-            ok(
-              subject == content,
+            Assert.equal(
+              subject,
+              content,
               "Should block script spawned via javascript uri"
             );
             SpecialPowers.removeObserver(
diff --git a/dom/base/test/chrome/bug418986-1.js b/dom/base/test/chrome/bug418986-1.js
index 7c39df0c13ca..e7e3c63b5c7f 100644
--- a/dom/base/test/chrome/bug418986-1.js
+++ b/dom/base/test/chrome/bug418986-1.js
@@ -1,4 +1,7 @@
 /* globals chromeWindow */
+
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 // The main test function.
 var test = function (isContent) {
   SimpleTest.waitForExplicitFinish();
diff --git a/dom/base/test/common_postMessages.js b/dom/base/test/common_postMessages.js
index c4836fdd777f..044f3e7f3461 100644
--- a/dom/base/test/common_postMessages.js
+++ b/dom/base/test/common_postMessages.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 function getType(a) {
   if (a === null || a === undefined) {
     return "null";
diff --git a/dom/base/test/file_bug1008126_worker.js b/dom/base/test/file_bug1008126_worker.js
index aaba278de5ff..4e418d777eae 100644
--- a/dom/base/test/file_bug1008126_worker.js
+++ b/dom/base/test/file_bug1008126_worker.js
@@ -3,6 +3,8 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 var gEntry1 = "data_1.txt";
 var gEntry2 = "data_2.txt";
 var gEntry3 = "data_big.txt";
diff --git a/dom/base/test/file_bug945152_worker.js b/dom/base/test/file_bug945152_worker.js
index 9664045b6d49..c0feebf0d631 100644
--- a/dom/base/test/file_bug945152_worker.js
+++ b/dom/base/test/file_bug945152_worker.js
@@ -1,3 +1,4 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
 var gData1 = "TEST_DATA_1:ABCDEFGHIJKLMNOPQRSTUVWXYZ";
 var gData2 = "TEST_DATA_2:1234567890";
 var gPaddingChar = ".";
diff --git a/dom/base/test/meta_viewport/viewport_helpers.js b/dom/base/test/meta_viewport/viewport_helpers.js
index d4d346b5d0a6..cad661354974 100644
--- a/dom/base/test/meta_viewport/viewport_helpers.js
+++ b/dom/base/test/meta_viewport/viewport_helpers.js
@@ -40,5 +40,6 @@ function getViewportInfo(aDisplayWidth, aDisplayHeight) {
 }
 
 function fuzzeq(a, b, msg) {
+  // eslint-disable-next-line mozilla/no-comparison-or-assignment-inside-ok
   ok(Math.abs(a - b) < 1e-6, msg);
 }
diff --git a/dom/events/test/pointerevents/mochitest_support_external.js b/dom/events/test/pointerevents/mochitest_support_external.js
index 7f22166fddf8..7a758a8c5f33 100644
--- a/dom/events/test/pointerevents/mochitest_support_external.js
+++ b/dom/events/test/pointerevents/mochitest_support_external.js
@@ -2,6 +2,8 @@
 // to tests on auto MochiTest system with minimum changes.
 // Author: Maksim Lebedev <alessarik@gmail.com>
 
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 // Function allows to prepare our tests after load document
 addEventListener(
   "load",
diff --git a/dom/events/test/test_bug336682.js b/dom/events/test/test_bug336682.js
index e673f1eb9907..11bd7d46bbf5 100644
--- a/dom/events/test/test_bug336682.js
+++ b/dom/events/test/test_bug336682.js
@@ -4,6 +4,8 @@
  * Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/licenses/publicdomain/
  */
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 var gState = 0;
 /**
  * After all the on/offline handlers run,
diff --git a/dom/file/tests/common_blob.js b/dom/file/tests/common_blob.js
index 261909af0dab..39ece679e098 100644
--- a/dom/file/tests/common_blob.js
+++ b/dom/file/tests/common_blob.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 const RANGE_1 = 1;
 const RANGE_2 = 2;
 
diff --git a/dom/file/tests/worker_blob_reading.js b/dom/file/tests/worker_blob_reading.js
index f57161c22081..8ad421062f86 100644
--- a/dom/file/tests/worker_blob_reading.js
+++ b/dom/file/tests/worker_blob_reading.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 importScripts("common_blob_reading.js");
 
 function info(message) {
diff --git a/dom/file/tests/worker_fileReader.js b/dom/file/tests/worker_fileReader.js
index 2e8408d1bbb8..fe7c49e64fa3 100644
--- a/dom/file/tests/worker_fileReader.js
+++ b/dom/file/tests/worker_fileReader.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 importScripts("common_fileReader.js");
 
 function ok(a, msg) {
diff --git a/dom/html/test/formData_test.js b/dom/html/test/formData_test.js
index 3997aff4d1cf..8dff5bd60604 100644
--- a/dom/html/test/formData_test.js
+++ b/dom/html/test/formData_test.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 function testHas() {
   var f = new FormData();
   f.append("foo", "bar");
diff --git a/dom/indexedDB/test/helpers.js b/dom/indexedDB/test/helpers.js
index 3555abf72257..f4ef6c279987 100644
--- a/dom/indexedDB/test/helpers.js
+++ b/dom/indexedDB/test/helpers.js
@@ -3,6 +3,8 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 // testSteps is expected to be defined by the test using this file.
 /* global testSteps:false */
 
diff --git a/dom/localstorage/test/unit/databaseShadowing-shared.js b/dom/localstorage/test/unit/databaseShadowing-shared.js
index ffee8579cb5f..77d6c09e3956 100644
--- a/dom/localstorage/test/unit/databaseShadowing-shared.js
+++ b/dom/localstorage/test/unit/databaseShadowing-shared.js
@@ -1,5 +1,7 @@
 /* import-globals-from head.js */
 
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 const principalInfos = [
   { url: "http://example.com", attrs: {} },
 
diff --git a/dom/reporting/tests/common_deprecated.js b/dom/reporting/tests/common_deprecated.js
index 8f8415fcf34d..1ef08884b472 100644
--- a/dom/reporting/tests/common_deprecated.js
+++ b/dom/reporting/tests/common_deprecated.js
@@ -1,5 +1,7 @@
 let testingInterface;
 
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 // eslint-disable-next-line no-unused-vars
 function test_deprecatedInterface() {
   info("Testing DeprecatedTestingInterface report");
@@ -34,7 +36,7 @@ function test_deprecatedInterface() {
           .replace("worker_deprecated.js", "common_deprecated.js"),
         "We have a sourceFile"
       );
-      is(report.body.lineNumber, 48, "We have a lineNumber");
+      is(report.body.lineNumber, 50, "We have a lineNumber");
       is(report.body.columnNumber, 24, "We have a columnNumber");
 
       obs.disconnect();
@@ -86,7 +88,7 @@ function test_deprecatedMethod() {
           .replace("worker_deprecated.js", "common_deprecated.js"),
         "We have a sourceFile"
       );
-      is(report.body.lineNumber, 100, "We have a lineNumber");
+      is(report.body.lineNumber, 102, "We have a lineNumber");
       is(report.body.columnNumber, 22, "We have a columnNumber");
 
       obs.disconnect();
@@ -167,7 +169,7 @@ function test_deprecatedAttribute() {
           .replace("worker_deprecated.js", "common_deprecated.js"),
         "We have a sourceFile"
       );
-      is(report.body.lineNumber, 181, "We have a lineNumber");
+      is(report.body.lineNumber, 183, "We have a lineNumber");
       is(report.body.columnNumber, 8, "We have a columnNumber");
 
       obs.disconnect();
diff --git a/dom/reporting/tests/worker_deprecated.js b/dom/reporting/tests/worker_deprecated.js
index f6b57896f6fd..934efaa57ad4 100644
--- a/dom/reporting/tests/worker_deprecated.js
+++ b/dom/reporting/tests/worker_deprecated.js
@@ -1,4 +1,5 @@
 /* eslint-disable no-undef */
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
 
 // eslint-disable-next-line no-unused-vars
 function ok(a, msg) {
diff --git a/dom/serviceworkers/test/close_test.js b/dom/serviceworkers/test/close_test.js
index 07f85617ef0b..0609782e5efd 100644
--- a/dom/serviceworkers/test/close_test.js
+++ b/dom/serviceworkers/test/close_test.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 function ok(v, msg) {
   client.postMessage({ status: "ok", result: !!v, message: msg });
 }
diff --git a/dom/serviceworkers/test/eventsource/eventsource_cors_response_intercept_worker.js b/dom/serviceworkers/test/eventsource/eventsource_cors_response_intercept_worker.js
index c2e5d416e7f3..31a816562582 100644
--- a/dom/serviceworkers/test/eventsource/eventsource_cors_response_intercept_worker.js
+++ b/dom/serviceworkers/test/eventsource/eventsource_cors_response_intercept_worker.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 // Cross origin request
 var prefix = "http://example.com/tests/dom/serviceworkers/test/eventsource/";
 
diff --git a/dom/serviceworkers/test/eventsource/eventsource_mixed_content_cors_response_intercept_worker.js b/dom/serviceworkers/test/eventsource/eventsource_mixed_content_cors_response_intercept_worker.js
index 9cb8d2d61f2a..9cfca63db997 100644
--- a/dom/serviceworkers/test/eventsource/eventsource_mixed_content_cors_response_intercept_worker.js
+++ b/dom/serviceworkers/test/eventsource/eventsource_mixed_content_cors_response_intercept_worker.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 var prefix = "http://example.com/tests/dom/serviceworkers/test/eventsource/";
 
 self.importScripts("eventsource_worker_helper.js");
diff --git a/dom/serviceworkers/test/eventsource/eventsource_opaque_response_intercept_worker.js b/dom/serviceworkers/test/eventsource/eventsource_opaque_response_intercept_worker.js
index 5c8c75a1618d..84d406ac47bb 100644
--- a/dom/serviceworkers/test/eventsource/eventsource_opaque_response_intercept_worker.js
+++ b/dom/serviceworkers/test/eventsource/eventsource_opaque_response_intercept_worker.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 // Cross origin request
 var prefix = "http://example.com/tests/dom/serviceworkers/test/eventsource/";
 
diff --git a/dom/serviceworkers/test/eventsource/eventsource_synthetic_response_intercept_worker.js b/dom/serviceworkers/test/eventsource/eventsource_synthetic_response_intercept_worker.js
index 72780e297918..ec3f0309c2fd 100644
--- a/dom/serviceworkers/test/eventsource/eventsource_synthetic_response_intercept_worker.js
+++ b/dom/serviceworkers/test/eventsource/eventsource_synthetic_response_intercept_worker.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 self.importScripts("eventsource_worker_helper.js");
 
 self.addEventListener("fetch", function (event) {
diff --git a/dom/serviceworkers/test/test_serviceworker_interfaces.js b/dom/serviceworkers/test/test_serviceworker_interfaces.js
index 2e902ebd70a1..c13c228d7173 100644
--- a/dom/serviceworkers/test/test_serviceworker_interfaces.js
+++ b/dom/serviceworkers/test/test_serviceworker_interfaces.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 // This is a list of all interfaces that are exposed to workers.
 // Please only add things to this list with great care and proper review
 // from the associated module peers.
diff --git a/dom/url/tests/protocol_worker.js b/dom/url/tests/protocol_worker.js
index c038254a4c15..81e761ee0ef3 100644
--- a/dom/url/tests/protocol_worker.js
+++ b/dom/url/tests/protocol_worker.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 function ok(a, msg) {
   postMessage({ type: "status", status: !!a, msg });
 }
diff --git a/dom/url/tests/urlSearchParams_commons.js b/dom/url/tests/urlSearchParams_commons.js
index 3a1dcb280737..4a1308b94b61 100644
--- a/dom/url/tests/urlSearchParams_commons.js
+++ b/dom/url/tests/urlSearchParams_commons.js
@@ -1,5 +1,9 @@
 /* import-globals-from urlSearchParams_worker.js */
 
+// This file gets included into a worker which doesn't have any
+// assertion methods besides `ok` and `is`.
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 function testSimpleURLSearchParams() {
   var u = new URLSearchParams();
   ok(u, "URLSearchParams created");
diff --git a/dom/workers/test/WorkerDebugger.console_debugger.js b/dom/workers/test/WorkerDebugger.console_debugger.js
index a8b249320025..805b7fb387fa 100644
--- a/dom/workers/test/WorkerDebugger.console_debugger.js
+++ b/dom/workers/test/WorkerDebugger.console_debugger.js
@@ -1,5 +1,7 @@
 "use strict";
 
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 function ok(a, msg) {
   postMessage(JSON.stringify({ type: "status", what: !!a, msg }));
 }
diff --git a/dom/workers/test/bug1014466_worker.js b/dom/workers/test/bug1014466_worker.js
index 2161954d2b5c..e06979d7b350 100644
--- a/dom/workers/test/bug1014466_worker.js
+++ b/dom/workers/test/bug1014466_worker.js
@@ -3,6 +3,8 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 function ok(a, msg) {
   postMessage({ type: "status", status: !!a, msg });
 }
diff --git a/dom/workers/test/notification_permission_worker.js b/dom/workers/test/notification_permission_worker.js
index 0e6b96d97511..0551247d078b 100644
--- a/dom/workers/test/notification_permission_worker.js
+++ b/dom/workers/test/notification_permission_worker.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 function info(message) {
   dump("INFO: " + message + "\n");
 }
diff --git a/dom/workers/test/notification_worker.js b/dom/workers/test/notification_worker.js
index 87aa02ac05d3..b97a4eb50528 100644
--- a/dom/workers/test/notification_worker.js
+++ b/dom/workers/test/notification_worker.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 function ok(test, message) {
   postMessage({ type: "ok", test, message });
 }
diff --git a/dom/workers/test/notification_worker_child-child.js b/dom/workers/test/notification_worker_child-child.js
index 236e314e47b1..9356f1be7a71 100644
--- a/dom/workers/test/notification_worker_child-child.js
+++ b/dom/workers/test/notification_worker_child-child.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 function ok(test, message) {
   postMessage({ type: "ok", test, message });
 }
diff --git a/dom/workers/test/onLine_worker_child.js b/dom/workers/test/onLine_worker_child.js
index 92542c018f05..cee3052c90d4 100644
--- a/dom/workers/test/onLine_worker_child.js
+++ b/dom/workers/test/onLine_worker_child.js
@@ -3,10 +3,7 @@
  * http://creativecommons.org/licenses/publicdomain/
  */
 
-/*
- * Any copyright is dedicated to the Public Domain.
- * http://creativecommons.org/licenses/publicdomain/
- */
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
 
 function info(text) {
   dump("Test for Bug 925437: worker: " + text + "\n");
diff --git a/dom/workers/test/onLine_worker_head.js b/dom/workers/test/onLine_worker_head.js
index 632821b1f4e5..8c6d601aa53e 100644
--- a/dom/workers/test/onLine_worker_head.js
+++ b/dom/workers/test/onLine_worker_head.js
@@ -3,6 +3,8 @@
  * http://creativecommons.org/licenses/publicdomain/
  */
 
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 function info(text) {
   dump("Test for Bug 925437: worker: " + text + "\n");
 }
diff --git a/dom/workers/test/promise_worker.js b/dom/workers/test/promise_worker.js
index fd4a9177d617..1c2d080e5bb5 100644
--- a/dom/workers/test/promise_worker.js
+++ b/dom/workers/test/promise_worker.js
@@ -1,5 +1,7 @@
 "use strict";
 
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 function ok(a, msg) {
   dump("OK: " + !!a + "  =>  " + a + " " + msg + "\n");
   postMessage({ type: "status", status: !!a, msg: a + ": " + msg });
diff --git a/dom/workers/test/test_worker_interfaces.js b/dom/workers/test/test_worker_interfaces.js
index 47ba833fbd5f..335c7d74b601 100644
--- a/dom/workers/test/test_worker_interfaces.js
+++ b/dom/workers/test/test_worker_interfaces.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 // This is a list of all interfaces that are exposed to workers.
 // Please only add things to this list with great care and proper review
 // from the associated module peers.
diff --git a/dom/xhr/tests/test_XHR.js b/dom/xhr/tests/test_XHR.js
index 12eb06e4f6ad..0034f8a0eb48 100644
--- a/dom/xhr/tests/test_XHR.js
+++ b/dom/xhr/tests/test_XHR.js
@@ -1,4 +1,7 @@
 "use strict";
+
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 SimpleTest.waitForExplicitFinish();
 
 var gen = runTests();
diff --git a/dom/xhr/tests/test_XHR_timeout.js b/dom/xhr/tests/test_XHR_timeout.js
index 1e75c1c1748a..69986770e131 100644
--- a/dom/xhr/tests/test_XHR_timeout.js
+++ b/dom/xhr/tests/test_XHR_timeout.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 /* Notes:
    - All times are expressed in milliseconds in this test suite.
    - Test harness code is at the end of this file.
diff --git a/dom/xhr/tests/test_worker_xhr_system.js b/dom/xhr/tests/test_worker_xhr_system.js
index 23137801a05f..6ac86f08b56e 100644
--- a/dom/xhr/tests/test_worker_xhr_system.js
+++ b/dom/xhr/tests/test_worker_xhr_system.js
@@ -1,3 +1,5 @@
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 function ok(what, msg) {
   postMessage({ event: msg, test: "ok", a: what });
 }
diff --git a/dom/xhr/tests/worker_temporaryFileBlob.js b/dom/xhr/tests/worker_temporaryFileBlob.js
index 50f071bab763..056b826e0079 100644
--- a/dom/xhr/tests/worker_temporaryFileBlob.js
+++ b/dom/xhr/tests/worker_temporaryFileBlob.js
@@ -1,4 +1,7 @@
 /* eslint-env worker */
+
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 importScripts("common_temporaryFileBlob.js");
 
 function info(msg) {
diff --git a/gfx/tests/browser/browser_native_font_cache_macos.js b/gfx/tests/browser/browser_native_font_cache_macos.js
index 919a5c7a72b4..e71ccbf5a60c 100644
--- a/gfx/tests/browser/browser_native_font_cache_macos.js
+++ b/gfx/tests/browser/browser_native_font_cache_macos.js
@@ -87,8 +87,9 @@ add_task(async () => {
       const nfrm_match = nfrm_line.exec(copiedText);
       if (nfrm_match) {
         const nfrm_mb = nfrm_match[1];
-        ok(
-          nfrm_mb < MB_EXCLUSIVE_MAX,
+        Assert.less(
+          nfrm_mb,
+          MB_EXCLUSIVE_MAX,
           `native-font-resource-mac ${nfrm_mb} MB should be less than ${MB_EXCLUSIVE_MAX} MB.`
         );
       } else {
@@ -102,8 +103,9 @@ add_task(async () => {
         const gfx_match = gfx_line.exec(copiedText);
         if (gfx_match && gfx_match.index < om_match.index) {
           const gfx_mb = gfx_match[1];
-          ok(
-            gfx_mb < MB_EXCLUSIVE_MAX,
+          Assert.less(
+            gfx_mb,
+            MB_EXCLUSIVE_MAX,
             `Explicit Allocations gfx ${gfx_mb} MB should be less than ${MB_EXCLUSIVE_MAX} MB.`
           );
         } else {
diff --git a/gfx/tests/browser/browser_windowless_troubleshoot_crash.js b/gfx/tests/browser/browser_windowless_troubleshoot_crash.js
index 44fc50e2f8f7..ecfc4da0928b 100644
--- a/gfx/tests/browser/browser_windowless_troubleshoot_crash.js
+++ b/gfx/tests/browser/browser_windowless_troubleshoot_crash.js
@@ -45,8 +45,9 @@ add_task(async function test_windowlessBrowserTroubleshootCrash() {
   );
   var data = await Troubleshoot.snapshot();
 
-  ok(
-    data.graphics.windowLayerManagerType !== "None",
+  Assert.notStrictEqual(
+    data.graphics.windowLayerManagerType,
+    "None",
     "windowless browser window should not set windowLayerManagerType to 'None'"
   );
 
diff --git a/image/test/browser/browser_offscreen_image_in_out_of_process_iframe.js b/image/test/browser/browser_offscreen_image_in_out_of_process_iframe.js
index b431902eb7ec..363f7016394b 100644
--- a/image/test/browser/browser_offscreen_image_in_out_of_process_iframe.js
+++ b/image/test/browser/browser_offscreen_image_in_out_of_process_iframe.js
@@ -140,7 +140,7 @@ add_task(async function () {
     await new Promise(resolve => requestAnimationFrame(resolve));
 
     frameCount = await SpecialPowers.spawn(iframe, [1000], observeFrameUpdate);
-    ok(frameCount > 0, "There should be frameUpdate(s)");
+    Assert.greater(frameCount, 0, "There should be frameUpdate(s)");
 
     await new Promise(resolve => requestAnimationFrame(resolve));
 
diff --git a/image/test/browser/head.js b/image/test/browser/head.js
index 29fc67a1a774..00f35babb277 100644
--- a/image/test/browser/head.js
+++ b/image/test/browser/head.js
@@ -27,7 +27,7 @@ function actOnMozImage(doc, id, func) {
 
 function assertPrefVal(name, val) {
   let boolValue = Services.prefs.getBoolPref(name);
-  ok(boolValue === val, `pref ${name} is set to ${val}`);
+  Assert.strictEqual(boolValue, val, `pref ${name} is set to ${val}`);
   if (boolValue !== val) {
     throw Error(`pref ${name} is not set to ${val}`);
   }
@@ -121,7 +121,7 @@ async function createMozIconInFile(ext, expectSuccess = true) {
     await waitLoad;
 
     const icon = content.document.getElementById(`moz-icon-${_ext}-${_kSize}`);
-    ok(icon !== null, `got a valid ${_ext} moz-icon`);
+    Assert.notStrictEqual(icon, null, `got a valid ${_ext} moz-icon`);
     is(icon.width, _kSize, `${_kSize} px width ${_ext} moz-icon`);
     is(icon.height, _kSize, `${_kSize} px height ${_ext} moz-icon`);
   };
diff --git a/layout/style/test/animation_utils.js b/layout/style/test/animation_utils.js
index 6f7ededcd41a..7239885e7c2e 100644
--- a/layout/style/test/animation_utils.js
+++ b/layout/style/test/animation_utils.js
@@ -4,6 +4,8 @@
 //
 //----------------------------------------------------------------------
 
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 function advance_clock(milliseconds) {
   SpecialPowers.DOMWindowUtils.advanceTimeAndRefresh(milliseconds);
 }
diff --git a/layout/style/test/chrome/bug418986-2.js b/layout/style/test/chrome/bug418986-2.js
index 6d2af235c382..c945eecca05c 100644
--- a/layout/style/test/chrome/bug418986-2.js
+++ b/layout/style/test/chrome/bug418986-2.js
@@ -1,5 +1,7 @@
 // # Bug 418986, part 2.
 
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 const is_chrome_window = window.location.protocol === "chrome:";
 
 const HTML_NS = "http://www.w3.org/1999/xhtml";
diff --git a/services/settings/test/unit/test_remote_settings.js b/services/settings/test/unit/test_remote_settings.js
index 09ceac2167e2..e1c0cf307ca7 100644
--- a/services/settings/test/unit/test_remote_settings.js
+++ b/services/settings/test/unit/test_remote_settings.js
@@ -355,6 +355,7 @@ add_task(async function test_get_falls_back_sorts_results() {
     order: "-id",
   });
 
+  // eslint-disable-next-line mozilla/no-comparison-or-assignment-inside-ok
   ok(records[0].id > records[records.length - 1].id, "records are sorted");
 
   clientWithDump.db.getLastModified = backup;
diff --git a/toolkit/components/antitracking/test/browser/browser_allowPermissionForTracker.js b/toolkit/components/antitracking/test/browser/browser_allowPermissionForTracker.js
index e628199ead80..3c559c898d2d 100644
--- a/toolkit/components/antitracking/test/browser/browser_allowPermissionForTracker.js
+++ b/toolkit/components/antitracking/test/browser/browser_allowPermissionForTracker.js
@@ -32,6 +32,8 @@ AntiTracking._createTask({
   allowList: false,
   callback: async _ => {
     document.cookie = "name=value";
+    // Assert isn't available in the webpage.
+    // eslint-disable-next-line mozilla/no-comparison-or-assignment-inside-ok
     ok(document.cookie != "", "Nothing is blocked");
 
     // requestStorageAccess should resolve
diff --git a/toolkit/components/antitracking/test/browser/browser_permissionInNormalWindows.js b/toolkit/components/antitracking/test/browser/browser_permissionInNormalWindows.js
index 69c5902a9118..68352b43087b 100644
--- a/toolkit/components/antitracking/test/browser/browser_permissionInNormalWindows.js
+++ b/toolkit/components/antitracking/test/browser/browser_permissionInNormalWindows.js
@@ -1,3 +1,6 @@
+// We're using custom message passing so don't have access to Assert.foo
+// everywhere. Disable the linter:
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
 AntiTracking.runTest(
   "Test whether we receive any persistent permissions in normal windows",
   // Blocking callback
diff --git a/toolkit/components/antitracking/test/browser/browser_permissionInNormalWindows_alwaysPartition.js b/toolkit/components/antitracking/test/browser/browser_permissionInNormalWindows_alwaysPartition.js
index 99c40bb0de8c..c9048cfcda7b 100644
--- a/toolkit/components/antitracking/test/browser/browser_permissionInNormalWindows_alwaysPartition.js
+++ b/toolkit/components/antitracking/test/browser/browser_permissionInNormalWindows_alwaysPartition.js
@@ -1,3 +1,7 @@
+// We're using custom message passing so don't have access to Assert.foo
+// everywhere. Disable the linter:
+/* eslint-disable mozilla/no-comparison-or-assignment-inside-ok */
+
 AntiTracking.runTest(
   "Test whether we receive any persistent permissions in normal windows",
   // Blocking callback
diff --git a/toolkit/components/places/tests/chrome/test_371798.xhtml b/toolkit/components/places/tests/chrome/test_371798.xhtml
index 33e866e51e19..f66ac74aaed4 100644
--- a/toolkit/components/places/tests/chrome/test_371798.xhtml
+++ b/toolkit/components/places/tests/chrome/test_371798.xhtml
@@ -57,7 +57,7 @@ const TEST_URI = Services.io.newURI("http://foo.com");
     let node = rootNode.getChild(i);
     // test that bm1 does not have new title
     if (node.bookmarkGuid == bm1.guid)
-      ok(node.title != "foo",
+      isnot(node.title, "foo",
          "Changing a bookmark's title did not affect the title of other bookmarks with the same URI");
   }
   rootNode.containerOpen = false;
diff --git a/widget/tests/browser/browser_test_clipboardcache.js b/widget/tests/browser/browser_test_clipboardcache.js
index 8cb6adb8b534..64deb99608c4 100644
--- a/widget/tests/browser/browser_test_clipboardcache.js
+++ b/widget/tests/browser/browser_test_clipboardcache.js
@@ -103,6 +103,10 @@ async function testCopyPaste(isPrivate) {
     document.execCommand("paste");
     return pastePromise;
   });
+
+  // Don't use Assert.strictEqual here because the test starts timing out,
+  // because the logging creates lots of copies of this very huge string.
+  // eslint-disable-next-line mozilla/no-comparison-or-assignment-inside-ok
   ok(readStr === Ipsum, "Read what we pasted");
 
   if (isPrivate) {