From dcc1d538839a037f877917f12d61999bdd3b4a21 Mon Sep 17 00:00:00 2001
From: Aaron <aaronklinker1@gmail.com>
Date: Sat, 20 Jul 2024 20:53:37 +0200
Subject: [PATCH 01/14] feat: Implement expand-prefs with tests

---
 src/extension-runners/chromium.js         | 44 ++++++++++-----
 src/util/expand-prefs.js                  | 32 +++++++++++
 tests/unit/test-util/test.expand-prefs.js | 68 +++++++++++++++++++++++
 3 files changed, 130 insertions(+), 14 deletions(-)
 create mode 100644 src/util/expand-prefs.js
 create mode 100644 tests/unit/test-util/test.expand-prefs.js

diff --git a/src/extension-runners/chromium.js b/src/extension-runners/chromium.js
index a2f91d813c..be90dbb65b 100644
--- a/src/extension-runners/chromium.js
+++ b/src/extension-runners/chromium.js
@@ -7,14 +7,15 @@ import fs from 'fs/promises';
 import path from 'path';
 
 import {
-  Launcher as ChromeLauncher,
   launch as defaultChromiumLaunch,
+  Launcher as ChromeLauncher,
 } from 'chrome-launcher';
 
 import { createLogger } from '../util/logger.js';
 import { TempDir } from '../util/temp-dir.js';
 import isDirectory from '../util/is-directory.js';
 import fileExists from '../util/file-exists.js';
+import expandPrefs from '../util/expand-prefs.js';
 
 const log = createLogger(import.meta.url);
 
@@ -28,6 +29,10 @@ export const DEFAULT_CHROME_FLAGS = ChromeLauncher.defaultFlags().filter(
   (flag) => !EXCLUDED_CHROME_FLAGS.includes(flag),
 );
 
+const DEFAULT_PREFS = {
+  'extensions.ui.developer_mode': true,
+};
+
 // This is a client for the Chrome Devtools protocol. The methods and results
 // are documented at https://chromedevtools.github.io/devtools-protocol/tot/
 class ChromeDevtoolsProtocolClient {
@@ -167,19 +172,6 @@ export class ChromiumExtensionRunner {
 
   // Method exported from the IExtensionRunner interface.
 
-  /**
-   * Returns the runner name.
-   */
-  getName() {
-    return 'Chromium';
-  }
-
-  async run() {
-    // Run should never be called more than once.
-    this._promiseSetupDone = this.setupInstance();
-    await this._promiseSetupDone;
-  }
-
   static async isUserDataDir(dirPath) {
     const localStatePath = path.join(dirPath, 'Local State');
     const defaultPath = path.join(dirPath, 'Default');
@@ -222,6 +214,19 @@ export class ChromiumExtensionRunner {
     };
   }
 
+  /**
+   * Returns the runner name.
+   */
+  getName() {
+    return 'Chromium';
+  }
+
+  async run() {
+    // Run should never be called more than once.
+    this._promiseSetupDone = this.setupInstance();
+    await this._promiseSetupDone;
+  }
+
   /**
    * Setup the Chromium Profile and run a Chromium instance.
    */
@@ -598,4 +603,15 @@ export class ChromiumExtensionRunner {
       }
     }
   }
+
+  /**
+   * Returns a deep preferences object based on a set of flat preferences, like
+   * "extensions.ui.developer_mode".
+   */
+  getPrefs() {
+    return expandPrefs({
+      ...DEFAULT_PREFS,
+      ...this.params.customPrefs,
+    });
+  }
 }
diff --git a/src/util/expand-prefs.js b/src/util/expand-prefs.js
new file mode 100644
index 0000000000..70fe95dd48
--- /dev/null
+++ b/src/util/expand-prefs.js
@@ -0,0 +1,32 @@
+/**
+ * Given an object where the keys are the flattened path to a
+ * preference, and the value is the value to set at that path, return
+ * an object where the paths are fully expanded.
+ */
+export default function expandPrefs(prefs) {
+  const prefsMap = new Map();
+  for (const [key, value] of Object.entries(prefs)) {
+    let submap = prefsMap;
+    const props = key.split('.');
+    const lastProp = props.pop();
+    for (const prop of props) {
+      if (!submap.has(prop)) {
+        submap.set(prop, new Map());
+      }
+      submap = submap.get(prop);
+      if (!(submap instanceof Map)) {
+        throw new Error(
+          `Cannot set ${key} because a value already exists at ${prop}`,
+        );
+      }
+    }
+    submap.set(lastProp, value);
+  }
+  return mapToObject(prefsMap);
+}
+
+function mapToObject(map) {
+  return Object.fromEntries(
+    Array.from(map, ([k, v]) => [k, v instanceof Map ? mapToObject(v) : v]),
+  );
+}
diff --git a/tests/unit/test-util/test.expand-prefs.js b/tests/unit/test-util/test.expand-prefs.js
new file mode 100644
index 0000000000..7e74d8da8c
--- /dev/null
+++ b/tests/unit/test-util/test.expand-prefs.js
@@ -0,0 +1,68 @@
+import { assert, expect } from 'chai';
+import { describe, it } from 'mocha';
+
+import expandPrefs from '../../../src/util/expand-prefs.js';
+
+describe('utils/expand-prefs', () => {
+  it('expands dot-deliminated preferences into a deep object', () => {
+    const input = {
+      a: 'a',
+      'b.c': 'c',
+      'd.e.f': 'f',
+    };
+    const expected = {
+      a: 'a',
+      b: {
+        c: 'c',
+      },
+      d: {
+        e: {
+          f: 'f',
+        },
+      },
+    };
+    const actual = expandPrefs(input);
+
+    assert.deepEqual(actual, expected);
+  });
+
+  it("doesn't pollute the object prototype", () => {
+    const call = 'overriden';
+    const input = {
+      'hasOwnProperty.call': call,
+    };
+    const expected = {
+      hasOwnProperty: {
+        call,
+      },
+    };
+    const actual = expandPrefs(input);
+
+    assert.notEqual(Object.prototype.hasOwnProperty.call, call);
+    assert.deepEqual(actual, expected);
+  });
+
+  it('throws an error when setting the child property of an already set parent', () => {
+    const input = {
+      a: 'a',
+      'a.b': 'b',
+    };
+
+    expect(() => expandPrefs(input)).to.throw(
+      'Cannot set a.b because a value already exists at a',
+    );
+  });
+
+  it('allows overriding a parent even if a child has already been set', () => {
+    const input = {
+      'a.b': 'b',
+      a: 'a',
+    };
+    const expected = {
+      a: 'a',
+    };
+    const actual = expandPrefs(input);
+
+    assert.deepEqual(actual, expected);
+  });
+});

From 0942b7b798e916cc4b65ebabf4f8e382031cf93c Mon Sep 17 00:00:00 2001
From: PatrykKuniczak <p.kuniczak@gmail.com>
Date: Fri, 20 Mar 2026 11:56:26 +0100
Subject: [PATCH 02/14] Implement chromiumPref with tests

---
 src/cmd/run.js                                |  7 +++
 src/extension-runners/chromium.js             | 11 ++--
 src/program.js                                | 17 +++++-
 src/util/chromium-preferences.js              | 30 +++++++++++
 src/util/expand-prefs.js                      |  5 +-
 tests/unit/test-cmd/test.run.js               | 18 ++++++-
 .../test-extension-runners/test.chromium.js   | 34 ++++++++++--
 .../test-util/test.chromium-preferences.js    | 54 +++++++++++++++++++
 tests/unit/test-util/test.expand-prefs.js     | 30 +++++------
 tests/unit/test.program.js                    | 21 ++++++++
 10 files changed, 195 insertions(+), 32 deletions(-)
 create mode 100644 src/util/chromium-preferences.js
 create mode 100644 tests/unit/test-util/test.chromium-preferences.js

diff --git a/src/cmd/run.js b/src/cmd/run.js
index d07d8df6dd..b619ca724a 100644
--- a/src/cmd/run.js
+++ b/src/cmd/run.js
@@ -51,6 +51,7 @@ export default async function run(
     firefoxApkComponent,
     // Chromium CLI options.
     chromiumBinary,
+    chromiumPref = new Map(),
     chromiumProfile,
   },
   {
@@ -84,6 +85,11 @@ export default async function run(
   // Create an alias for --pref since it has been transformed into an
   // object containing one or more preferences.
   const customPrefs = pref;
+
+  // Create an alias for --chromium-pref since it has been transformed into an
+  // object containing one or more preferences.
+  const customChromiumPrefs = chromiumPref;
+
   const manifestData = await getValidatedManifest(sourceDir);
 
   const profileDir = firefoxProfile || chromiumProfile;
@@ -191,6 +197,7 @@ export default async function run(
       ...commonRunnerParams,
       verbose,
       chromiumBinary,
+      customChromiumPrefs,
       chromiumProfile,
     };
 
diff --git a/src/extension-runners/chromium.js b/src/extension-runners/chromium.js
index be90dbb65b..987f66be19 100644
--- a/src/extension-runners/chromium.js
+++ b/src/extension-runners/chromium.js
@@ -29,9 +29,7 @@ export const DEFAULT_CHROME_FLAGS = ChromeLauncher.defaultFlags().filter(
   (flag) => !EXCLUDED_CHROME_FLAGS.includes(flag),
 );
 
-const DEFAULT_PREFS = {
-  'extensions.ui.developer_mode': true,
-};
+const DEFAULT_PREFS = new Map([['extensions.ui.developer_mode', true]]);
 
 // This is a client for the Chrome Devtools protocol. The methods and results
 // are documented at https://chromedevtools.github.io/devtools-protocol/tot/
@@ -609,9 +607,8 @@ export class ChromiumExtensionRunner {
    * "extensions.ui.developer_mode".
    */
   getPrefs() {
-    return expandPrefs({
-      ...DEFAULT_PREFS,
-      ...this.params.customPrefs,
-    });
+    return expandPrefs(
+      new Map([...DEFAULT_PREFS, ...this.params.customChromiumPrefs]),
+    );
   }
 }
diff --git a/src/program.js b/src/program.js
index 5daca429ba..4e1322f07c 100644
--- a/src/program.js
+++ b/src/program.js
@@ -10,15 +10,16 @@ import { Parser as yargsParser } from 'yargs/helpers';
 import defaultCommands from './cmd/index.js';
 import { UsageError } from './errors.js';
 import {
-  createLogger,
   consoleStream as defaultLogStream,
+  createLogger,
 } from './util/logger.js';
 import { coerceCLICustomPreference } from './firefox/preferences.js';
+import { coerceCLICustomChromiumPreference } from './util/chromium-preferences.js';
 import { checkForUpdates as defaultUpdateChecker } from './util/updates.js';
 import {
+  applyConfigToArgv as defaultApplyConfigToArgv,
   discoverConfigFiles as defaultConfigDiscovery,
   loadJSConfigFile as defaultLoadJSConfigFile,
-  applyConfigToArgv as defaultApplyConfigToArgv,
 } from './config.js';
 
 const log = createLogger(import.meta.url);
@@ -619,6 +620,18 @@ Example: $0 --help run.
         demandOption: false,
         type: 'string',
       },
+      'chromium-pref': {
+        describe:
+          'Launch chromium with a custom preference ' +
+          '(example: --chromium-pref=browser.theme.follows_system_colors=false). ' +
+          'You can repeat this option to set more than one ' +
+          'preference.',
+        demandOption: false,
+        requiresArg: true,
+        type: 'array',
+        coerce: (arg) =>
+          arg != null ? coerceCLICustomChromiumPreference(arg) : undefined,
+      },
       'chromium-profile': {
         describe: 'Path to a custom Chromium profile',
         demandOption: false,
diff --git a/src/util/chromium-preferences.js b/src/util/chromium-preferences.js
new file mode 100644
index 0000000000..80a81373e3
--- /dev/null
+++ b/src/util/chromium-preferences.js
@@ -0,0 +1,30 @@
+import { UsageError } from '../errors.js';
+
+export function coerceCLICustomChromiumPreference(cliPrefs) {
+  const chromiumPrefs = new Map();
+
+  for (const pref of cliPrefs) {
+    const prefsAry = pref.split('=');
+
+    if (prefsAry.length < 2) {
+      throw new UsageError(
+        `Incomplete custom preference: "${pref}". ` +
+          'Syntax expected: "prefname=prefvalue".',
+      );
+    }
+
+    const key = prefsAry[0];
+    let value = prefsAry.slice(1).join('=');
+
+
+    if (value === `${parseInt(value)}`) {
+      value = parseInt(value, 10);
+    } else if (value === 'true' || value === 'false') {
+      value = value === 'true';
+    }
+
+    chromiumPrefs.set(key, value);
+  }
+
+  return chromiumPrefs;
+}
diff --git a/src/util/expand-prefs.js b/src/util/expand-prefs.js
index 70fe95dd48..b5b2f23fcc 100644
--- a/src/util/expand-prefs.js
+++ b/src/util/expand-prefs.js
@@ -1,11 +1,12 @@
 /**
- * Given an object where the keys are the flattened path to a
+ * Given a Map where the keys are the flattened path to a
  * preference, and the value is the value to set at that path, return
  * an object where the paths are fully expanded.
  */
 export default function expandPrefs(prefs) {
   const prefsMap = new Map();
-  for (const [key, value] of Object.entries(prefs)) {
+
+  for (const [key, value] of prefs) {
     let submap = prefsMap;
     const props = key.split('.');
     const lastProp = props.pop();
diff --git a/tests/unit/test-cmd/test.run.js b/tests/unit/test-cmd/test.run.js
index 19f5f88e4c..b248e5687b 100644
--- a/tests/unit/test-cmd/test.run.js
+++ b/tests/unit/test-cmd/test.run.js
@@ -7,8 +7,8 @@ import { assert } from 'chai';
 import * as sinon from 'sinon';
 
 import {
-  fixturePath,
   FakeExtensionRunner,
+  fixturePath,
   getFakeFirefox,
   getFakeRemoteFirefox,
   mockModule,
@@ -341,6 +341,22 @@ describe('run', () => {
     );
   });
 
+  it('provides chromium custom preferences to the Chromium runner params', async () => {
+    const fakeChromiumPref = new Map([['extensions.ui.developer_mode', false]]);
+    const cmd = await prepareRun();
+    await cmd.run({
+      target: ['chromium'],
+      chromiumPref: fakeChromiumPref,
+    });
+
+    sinon.assert.calledWithMatch(chromiumRunnerStub, {
+      customChromiumPrefs: sinon.match.instanceOf(Map),
+    });
+
+    const { customChromiumPrefs } = chromiumRunnerStub.firstCall.args[0];
+    assert.strictEqual(customChromiumPrefs, fakeChromiumPref);
+  });
+
   it('creates multiple extension runners', async () => {
     const cmd = await prepareRun();
     await cmd.run({ target: ['firefox-android', 'firefox-desktop'] });
diff --git a/tests/unit/test-extension-runners/test.chromium.js b/tests/unit/test-extension-runners/test.chromium.js
index c3a22a116f..d31e9a89f4 100644
--- a/tests/unit/test-extension-runners/test.chromium.js
+++ b/tests/unit/test-extension-runners/test.chromium.js
@@ -2,7 +2,7 @@ import path from 'path';
 import EventEmitter from 'events';
 
 import { assert } from 'chai';
-import { describe, it, beforeEach } from 'mocha';
+import { beforeEach, describe, it } from 'mocha';
 import deepcopy from 'deepcopy';
 import fs from 'fs-extra';
 import * as sinon from 'sinon';
@@ -12,9 +12,7 @@ import {
   ChromiumExtensionRunner,
   DEFAULT_CHROME_FLAGS,
 } from '../../../src/extension-runners/chromium.js';
-import {
-  consoleStream, // instance is imported to inspect logged messages
-} from '../../../src/util/logger.js';
+import { consoleStream } from '../../../src/util/logger.js';
 import { TempDir, withTempDir } from '../../../src/util/temp-dir.js';
 import fileExists from '../../../src/util/file-exists.js';
 import isDirectory from '../../../src/util/is-directory.js';
@@ -602,6 +600,34 @@ describe('util/extension-runners/chromium', async () => {
     sinon.assert.calledOnce(fakeChromeInstance.kill);
   });
 
+  describe('getPrefs', () => {
+    it('merges default and custom preferences from a Map', () => {
+      const { params } = prepareExtensionRunnerParams({
+        params: {
+          customChromiumPrefs: new Map([
+            ['extensions.ui.developer_mode', false],
+            ['browser.theme.color', 'dark'],
+          ]),
+        },
+      });
+
+      const runnerInstance = new ChromiumExtensionRunner(params);
+
+      assert.deepEqual(runnerInstance.getPrefs(), {
+        extensions: {
+          ui: {
+            developer_mode: false,
+          },
+        },
+        browser: {
+          theme: {
+            color: 'dark',
+          },
+        },
+      });
+    });
+  });
+
   describe('reloadAllExtensions', () => {
     let runnerInstance;
 
diff --git a/tests/unit/test-util/test.chromium-preferences.js b/tests/unit/test-util/test.chromium-preferences.js
new file mode 100644
index 0000000000..1bdce2e724
--- /dev/null
+++ b/tests/unit/test-util/test.chromium-preferences.js
@@ -0,0 +1,54 @@
+import { describe, it } from 'mocha';
+import { assert } from 'chai';
+
+import { UsageError } from '../../../src/errors.js';
+import { coerceCLICustomChromiumPreference } from '../../../src/util/chromium-preferences.js';
+
+describe('util/chromium-preferences', () => {
+  describe('coerceCLICustomChromiumPreference', () => {
+    it('converts cli preferences into a Map', () => {
+      const prefs = coerceCLICustomChromiumPreference([
+        'extensions.ui.developer_mode=false',
+        'browser.theme.color=dark',
+      ]);
+
+      assert.instanceOf(prefs, Map);
+      assert.strictEqual(prefs.get('extensions.ui.developer_mode'), false);
+      assert.strictEqual(prefs.get('browser.theme.color'), 'dark');
+    });
+
+    it('converts integer values', () => {
+      const prefs = coerceCLICustomChromiumPreference(['some.int.pref=455']);
+
+      assert.strictEqual(prefs.get('some.int.pref'), 455);
+    });
+
+    it('supports string values containing equals signs', () => {
+      const prefs = coerceCLICustomChromiumPreference([
+        'some.string.pref=value=with=equals',
+      ]);
+
+      assert.strictEqual(prefs.get('some.string.pref'), 'value=with=equals');
+    });
+
+    it('throws on incomplete preferences', () => {
+      assert.throws(
+        () => coerceCLICustomChromiumPreference(['invalid.preference']),
+        UsageError,
+        'Incomplete custom preference: "invalid.preference". ' +
+          'Syntax expected: "prefname=prefvalue".',
+      );
+    });
+
+    it('accepts permissive Chromium preference keys', () => {
+      const prefs = coerceCLICustomChromiumPreference([
+        'net.http.server_properties:https://example.com=true',
+      ]);
+
+      assert.strictEqual(
+        prefs.get('net.http.server_properties:https://example.com'),
+        true,
+      );
+    });
+  });
+});
diff --git a/tests/unit/test-util/test.expand-prefs.js b/tests/unit/test-util/test.expand-prefs.js
index 7e74d8da8c..1e4a082735 100644
--- a/tests/unit/test-util/test.expand-prefs.js
+++ b/tests/unit/test-util/test.expand-prefs.js
@@ -5,11 +5,11 @@ import expandPrefs from '../../../src/util/expand-prefs.js';
 
 describe('utils/expand-prefs', () => {
   it('expands dot-deliminated preferences into a deep object', () => {
-    const input = {
-      a: 'a',
-      'b.c': 'c',
-      'd.e.f': 'f',
-    };
+    const input = new Map([
+      ['a', 'a'],
+      ['b.c', 'c'],
+      ['d.e.f', 'f'],
+    ]);
     const expected = {
       a: 'a',
       b: {
@@ -28,9 +28,7 @@ describe('utils/expand-prefs', () => {
 
   it("doesn't pollute the object prototype", () => {
     const call = 'overriden';
-    const input = {
-      'hasOwnProperty.call': call,
-    };
+    const input = new Map([['hasOwnProperty.call', call]]);
     const expected = {
       hasOwnProperty: {
         call,
@@ -43,10 +41,10 @@ describe('utils/expand-prefs', () => {
   });
 
   it('throws an error when setting the child property of an already set parent', () => {
-    const input = {
-      a: 'a',
-      'a.b': 'b',
-    };
+    const input = new Map([
+      ['a', 'a'],
+      ['a.b', 'b'],
+    ]);
 
     expect(() => expandPrefs(input)).to.throw(
       'Cannot set a.b because a value already exists at a',
@@ -54,10 +52,10 @@ describe('utils/expand-prefs', () => {
   });
 
   it('allows overriding a parent even if a child has already been set', () => {
-    const input = {
-      'a.b': 'b',
-      a: 'a',
-    };
+    const input = new Map([
+      ['a.b', 'b'],
+      ['a', 'a'],
+    ]);
     const expected = {
       a: 'a',
     };
diff --git a/tests/unit/test.program.js b/tests/unit/test.program.js
index 7eebe2f2e3..889a5b72a9 100644
--- a/tests/unit/test.program.js
+++ b/tests/unit/test.program.js
@@ -614,6 +614,27 @@ describe('program.main', () => {
     });
   });
 
+  it('converts chromium custom preferences into a Map', () => {
+    const fakeCommands = fake(commands, {
+      run: () => Promise.resolve(),
+    });
+    return execProgram(
+      [
+        'run',
+        '--chromium-pref',
+        'extensions.ui.developer_mode=false',
+        '--chromium-pref',
+        'browser.theme.color=dark',
+      ],
+      { commands: fakeCommands },
+    ).then(() => {
+      const { chromiumPref } = fakeCommands.run.firstCall.args[0];
+      assert.instanceOf(chromiumPref, Map);
+      assert.strictEqual(chromiumPref.get('extensions.ui.developer_mode'), false);
+      assert.strictEqual(chromiumPref.get('browser.theme.color'), 'dark');
+    });
+  });
+
   it('passes shouldExitProgram option to commands', () => {
     const fakeCommands = fake(commands, {
       lint: () => Promise.resolve(),

From a937f4158d3301a18129b85b4e62e6cd0464b44e Mon Sep 17 00:00:00 2001
From: PatrykKuniczak <p.kuniczak@gmail.com>
Date: Mon, 23 Mar 2026 09:21:47 +0100
Subject: [PATCH 03/14] Remove coerceCLICustomChromiumPreference and revert
 unnecessary changes(Map refactor and so on)

---
 src/cmd/run.js                                |  2 +-
 src/extension-runners/chromium.js             | 35 ++++++------
 src/program.js                                |  3 +-
 src/util/chromium-preferences.js              | 30 -----------
 src/util/expand-prefs.js                      |  5 +-
 tests/unit/test-cmd/test.run.js               |  2 +-
 .../test-extension-runners/test.chromium.js   | 16 +++---
 .../test-util/test.chromium-preferences.js    | 54 -------------------
 tests/unit/test-util/test.expand-prefs.js     | 30 ++++++-----
 tests/unit/test.program.js                    |  8 +--
 10 files changed, 52 insertions(+), 133 deletions(-)
 delete mode 100644 src/util/chromium-preferences.js
 delete mode 100644 tests/unit/test-util/test.chromium-preferences.js

diff --git a/src/cmd/run.js b/src/cmd/run.js
index b619ca724a..56e8f72815 100644
--- a/src/cmd/run.js
+++ b/src/cmd/run.js
@@ -51,7 +51,7 @@ export default async function run(
     firefoxApkComponent,
     // Chromium CLI options.
     chromiumBinary,
-    chromiumPref = new Map(),
+    chromiumPref = {},
     chromiumProfile,
   },
   {
diff --git a/src/extension-runners/chromium.js b/src/extension-runners/chromium.js
index 987f66be19..244491aa0f 100644
--- a/src/extension-runners/chromium.js
+++ b/src/extension-runners/chromium.js
@@ -29,7 +29,7 @@ export const DEFAULT_CHROME_FLAGS = ChromeLauncher.defaultFlags().filter(
   (flag) => !EXCLUDED_CHROME_FLAGS.includes(flag),
 );
 
-const DEFAULT_PREFS = new Map([['extensions.ui.developer_mode', true]]);
+const DEFAULT_PREFS = { 'extensions.ui.developer_mode': true };
 
 // This is a client for the Chrome Devtools protocol. The methods and results
 // are documented at https://chromedevtools.github.io/devtools-protocol/tot/
@@ -170,6 +170,19 @@ export class ChromiumExtensionRunner {
 
   // Method exported from the IExtensionRunner interface.
 
+  /**
+   * Returns the runner name.
+   */
+  getName() {
+    return 'Chromium';
+  }
+
+  async run() {
+    // Run should never be called more than once.
+    this._promiseSetupDone = this.setupInstance();
+    await this._promiseSetupDone;
+  }
+
   static async isUserDataDir(dirPath) {
     const localStatePath = path.join(dirPath, 'Local State');
     const defaultPath = path.join(dirPath, 'Default');
@@ -212,19 +225,6 @@ export class ChromiumExtensionRunner {
     };
   }
 
-  /**
-   * Returns the runner name.
-   */
-  getName() {
-    return 'Chromium';
-  }
-
-  async run() {
-    // Run should never be called more than once.
-    this._promiseSetupDone = this.setupInstance();
-    await this._promiseSetupDone;
-  }
-
   /**
    * Setup the Chromium Profile and run a Chromium instance.
    */
@@ -607,8 +607,9 @@ export class ChromiumExtensionRunner {
    * "extensions.ui.developer_mode".
    */
   getPrefs() {
-    return expandPrefs(
-      new Map([...DEFAULT_PREFS, ...this.params.customChromiumPrefs]),
-    );
+    return expandPrefs({
+      ...DEFAULT_PREFS,
+      ...this.params.customChromiumPrefs,
+    });
   }
 }
diff --git a/src/program.js b/src/program.js
index 4e1322f07c..711bdc9345 100644
--- a/src/program.js
+++ b/src/program.js
@@ -14,7 +14,6 @@ import {
   createLogger,
 } from './util/logger.js';
 import { coerceCLICustomPreference } from './firefox/preferences.js';
-import { coerceCLICustomChromiumPreference } from './util/chromium-preferences.js';
 import { checkForUpdates as defaultUpdateChecker } from './util/updates.js';
 import {
   applyConfigToArgv as defaultApplyConfigToArgv,
@@ -630,7 +629,7 @@ Example: $0 --help run.
         requiresArg: true,
         type: 'array',
         coerce: (arg) =>
-          arg != null ? coerceCLICustomChromiumPreference(arg) : undefined,
+          arg != null ? coerceCLICustomPreference(arg) : undefined,
       },
       'chromium-profile': {
         describe: 'Path to a custom Chromium profile',
diff --git a/src/util/chromium-preferences.js b/src/util/chromium-preferences.js
deleted file mode 100644
index 80a81373e3..0000000000
--- a/src/util/chromium-preferences.js
+++ /dev/null
@@ -1,30 +0,0 @@
-import { UsageError } from '../errors.js';
-
-export function coerceCLICustomChromiumPreference(cliPrefs) {
-  const chromiumPrefs = new Map();
-
-  for (const pref of cliPrefs) {
-    const prefsAry = pref.split('=');
-
-    if (prefsAry.length < 2) {
-      throw new UsageError(
-        `Incomplete custom preference: "${pref}". ` +
-          'Syntax expected: "prefname=prefvalue".',
-      );
-    }
-
-    const key = prefsAry[0];
-    let value = prefsAry.slice(1).join('=');
-
-
-    if (value === `${parseInt(value)}`) {
-      value = parseInt(value, 10);
-    } else if (value === 'true' || value === 'false') {
-      value = value === 'true';
-    }
-
-    chromiumPrefs.set(key, value);
-  }
-
-  return chromiumPrefs;
-}
diff --git a/src/util/expand-prefs.js b/src/util/expand-prefs.js
index b5b2f23fcc..70fe95dd48 100644
--- a/src/util/expand-prefs.js
+++ b/src/util/expand-prefs.js
@@ -1,12 +1,11 @@
 /**
- * Given a Map where the keys are the flattened path to a
+ * Given an object where the keys are the flattened path to a
  * preference, and the value is the value to set at that path, return
  * an object where the paths are fully expanded.
  */
 export default function expandPrefs(prefs) {
   const prefsMap = new Map();
-
-  for (const [key, value] of prefs) {
+  for (const [key, value] of Object.entries(prefs)) {
     let submap = prefsMap;
     const props = key.split('.');
     const lastProp = props.pop();
diff --git a/tests/unit/test-cmd/test.run.js b/tests/unit/test-cmd/test.run.js
index b248e5687b..6467adae1a 100644
--- a/tests/unit/test-cmd/test.run.js
+++ b/tests/unit/test-cmd/test.run.js
@@ -7,8 +7,8 @@ import { assert } from 'chai';
 import * as sinon from 'sinon';
 
 import {
-  FakeExtensionRunner,
   fixturePath,
+  FakeExtensionRunner,
   getFakeFirefox,
   getFakeRemoteFirefox,
   mockModule,
diff --git a/tests/unit/test-extension-runners/test.chromium.js b/tests/unit/test-extension-runners/test.chromium.js
index d31e9a89f4..012cbbb9f5 100644
--- a/tests/unit/test-extension-runners/test.chromium.js
+++ b/tests/unit/test-extension-runners/test.chromium.js
@@ -2,7 +2,7 @@ import path from 'path';
 import EventEmitter from 'events';
 
 import { assert } from 'chai';
-import { beforeEach, describe, it } from 'mocha';
+import { describe, it, beforeEach } from 'mocha';
 import deepcopy from 'deepcopy';
 import fs from 'fs-extra';
 import * as sinon from 'sinon';
@@ -12,7 +12,9 @@ import {
   ChromiumExtensionRunner,
   DEFAULT_CHROME_FLAGS,
 } from '../../../src/extension-runners/chromium.js';
-import { consoleStream } from '../../../src/util/logger.js';
+import {
+  consoleStream, // instance is imported to inspect logged messages
+} from '../../../src/util/logger.js';
 import { TempDir, withTempDir } from '../../../src/util/temp-dir.js';
 import fileExists from '../../../src/util/file-exists.js';
 import isDirectory from '../../../src/util/is-directory.js';
@@ -601,13 +603,13 @@ describe('util/extension-runners/chromium', async () => {
   });
 
   describe('getPrefs', () => {
-    it('merges default and custom preferences from a Map', () => {
+    it('merges default and custom preferences from an object', () => {
       const { params } = prepareExtensionRunnerParams({
         params: {
-          customChromiumPrefs: new Map([
-            ['extensions.ui.developer_mode', false],
-            ['browser.theme.color', 'dark'],
-          ]),
+          customChromiumPrefs: {
+            'extensions.ui.developer_mode': false,
+            'browser.theme.color': 'dark',
+          },
         },
       });
 
diff --git a/tests/unit/test-util/test.chromium-preferences.js b/tests/unit/test-util/test.chromium-preferences.js
deleted file mode 100644
index 1bdce2e724..0000000000
--- a/tests/unit/test-util/test.chromium-preferences.js
+++ /dev/null
@@ -1,54 +0,0 @@
-import { describe, it } from 'mocha';
-import { assert } from 'chai';
-
-import { UsageError } from '../../../src/errors.js';
-import { coerceCLICustomChromiumPreference } from '../../../src/util/chromium-preferences.js';
-
-describe('util/chromium-preferences', () => {
-  describe('coerceCLICustomChromiumPreference', () => {
-    it('converts cli preferences into a Map', () => {
-      const prefs = coerceCLICustomChromiumPreference([
-        'extensions.ui.developer_mode=false',
-        'browser.theme.color=dark',
-      ]);
-
-      assert.instanceOf(prefs, Map);
-      assert.strictEqual(prefs.get('extensions.ui.developer_mode'), false);
-      assert.strictEqual(prefs.get('browser.theme.color'), 'dark');
-    });
-
-    it('converts integer values', () => {
-      const prefs = coerceCLICustomChromiumPreference(['some.int.pref=455']);
-
-      assert.strictEqual(prefs.get('some.int.pref'), 455);
-    });
-
-    it('supports string values containing equals signs', () => {
-      const prefs = coerceCLICustomChromiumPreference([
-        'some.string.pref=value=with=equals',
-      ]);
-
-      assert.strictEqual(prefs.get('some.string.pref'), 'value=with=equals');
-    });
-
-    it('throws on incomplete preferences', () => {
-      assert.throws(
-        () => coerceCLICustomChromiumPreference(['invalid.preference']),
-        UsageError,
-        'Incomplete custom preference: "invalid.preference". ' +
-          'Syntax expected: "prefname=prefvalue".',
-      );
-    });
-
-    it('accepts permissive Chromium preference keys', () => {
-      const prefs = coerceCLICustomChromiumPreference([
-        'net.http.server_properties:https://example.com=true',
-      ]);
-
-      assert.strictEqual(
-        prefs.get('net.http.server_properties:https://example.com'),
-        true,
-      );
-    });
-  });
-});
diff --git a/tests/unit/test-util/test.expand-prefs.js b/tests/unit/test-util/test.expand-prefs.js
index 1e4a082735..7e74d8da8c 100644
--- a/tests/unit/test-util/test.expand-prefs.js
+++ b/tests/unit/test-util/test.expand-prefs.js
@@ -5,11 +5,11 @@ import expandPrefs from '../../../src/util/expand-prefs.js';
 
 describe('utils/expand-prefs', () => {
   it('expands dot-deliminated preferences into a deep object', () => {
-    const input = new Map([
-      ['a', 'a'],
-      ['b.c', 'c'],
-      ['d.e.f', 'f'],
-    ]);
+    const input = {
+      a: 'a',
+      'b.c': 'c',
+      'd.e.f': 'f',
+    };
     const expected = {
       a: 'a',
       b: {
@@ -28,7 +28,9 @@ describe('utils/expand-prefs', () => {
 
   it("doesn't pollute the object prototype", () => {
     const call = 'overriden';
-    const input = new Map([['hasOwnProperty.call', call]]);
+    const input = {
+      'hasOwnProperty.call': call,
+    };
     const expected = {
       hasOwnProperty: {
         call,
@@ -41,10 +43,10 @@ describe('utils/expand-prefs', () => {
   });
 
   it('throws an error when setting the child property of an already set parent', () => {
-    const input = new Map([
-      ['a', 'a'],
-      ['a.b', 'b'],
-    ]);
+    const input = {
+      a: 'a',
+      'a.b': 'b',
+    };
 
     expect(() => expandPrefs(input)).to.throw(
       'Cannot set a.b because a value already exists at a',
@@ -52,10 +54,10 @@ describe('utils/expand-prefs', () => {
   });
 
   it('allows overriding a parent even if a child has already been set', () => {
-    const input = new Map([
-      ['a.b', 'b'],
-      ['a', 'a'],
-    ]);
+    const input = {
+      'a.b': 'b',
+      a: 'a',
+    };
     const expected = {
       a: 'a',
     };
diff --git a/tests/unit/test.program.js b/tests/unit/test.program.js
index 889a5b72a9..e159aec3e8 100644
--- a/tests/unit/test.program.js
+++ b/tests/unit/test.program.js
@@ -614,7 +614,7 @@ describe('program.main', () => {
     });
   });
 
-  it('converts chromium custom preferences into a Map', () => {
+  it('converts chromium custom preferences into an object', () => {
     const fakeCommands = fake(commands, {
       run: () => Promise.resolve(),
     });
@@ -629,9 +629,9 @@ describe('program.main', () => {
       { commands: fakeCommands },
     ).then(() => {
       const { chromiumPref } = fakeCommands.run.firstCall.args[0];
-      assert.instanceOf(chromiumPref, Map);
-      assert.strictEqual(chromiumPref.get('extensions.ui.developer_mode'), false);
-      assert.strictEqual(chromiumPref.get('browser.theme.color'), 'dark');
+      assert.isObject(chromiumPref);
+      assert.strictEqual(chromiumPref['extensions.ui.developer_mode'], false);
+      assert.strictEqual(chromiumPref['browser.theme.color'], 'dark');
     });
   });
 

From 956a22c12caa844a7d23c7ff4cd717a69537161e Mon Sep 17 00:00:00 2001
From: PatrykKuniczak <p.kuniczak@gmail.com>
Date: Mon, 23 Mar 2026 09:23:21 +0100
Subject: [PATCH 04/14] Rename DEFAULT_PREFS to DEFAULT_CHROMIUM_PREFS

---
 src/extension-runners/chromium.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/extension-runners/chromium.js b/src/extension-runners/chromium.js
index 244491aa0f..dbb960fb3b 100644
--- a/src/extension-runners/chromium.js
+++ b/src/extension-runners/chromium.js
@@ -7,8 +7,8 @@ import fs from 'fs/promises';
 import path from 'path';
 
 import {
-  launch as defaultChromiumLaunch,
   Launcher as ChromeLauncher,
+  launch as defaultChromiumLaunch,
 } from 'chrome-launcher';
 
 import { createLogger } from '../util/logger.js';
@@ -29,7 +29,7 @@ export const DEFAULT_CHROME_FLAGS = ChromeLauncher.defaultFlags().filter(
   (flag) => !EXCLUDED_CHROME_FLAGS.includes(flag),
 );
 
-const DEFAULT_PREFS = { 'extensions.ui.developer_mode': true };
+const DEFAULT_CHROMIUM_PREFS = { 'extensions.ui.developer_mode': true };
 
 // This is a client for the Chrome Devtools protocol. The methods and results
 // are documented at https://chromedevtools.github.io/devtools-protocol/tot/
@@ -608,7 +608,7 @@ export class ChromiumExtensionRunner {
    */
   getPrefs() {
     return expandPrefs({
-      ...DEFAULT_PREFS,
+      ...DEFAULT_CHROMIUM_PREFS,
       ...this.params.customChromiumPrefs,
     });
   }

From 90e743dedd7d133d5e727f5aa4d8ccd140d5b8ce Mon Sep 17 00:00:00 2001
From: PatrykKuniczak <p.kuniczak@gmail.com>
Date: Mon, 23 Mar 2026 09:25:51 +0100
Subject: [PATCH 05/14] Use object instead of Map for "provides chromium
 custom..." test of test.run.js

---
 tests/unit/test-cmd/test.run.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/unit/test-cmd/test.run.js b/tests/unit/test-cmd/test.run.js
index 6467adae1a..05595877bc 100644
--- a/tests/unit/test-cmd/test.run.js
+++ b/tests/unit/test-cmd/test.run.js
@@ -342,7 +342,7 @@ describe('run', () => {
   });
 
   it('provides chromium custom preferences to the Chromium runner params', async () => {
-    const fakeChromiumPref = new Map([['extensions.ui.developer_mode', false]]);
+    const fakeChromiumPref = { 'extensions.ui.developer_mode': false };
     const cmd = await prepareRun();
     await cmd.run({
       target: ['chromium'],
@@ -350,7 +350,7 @@ describe('run', () => {
     });
 
     sinon.assert.calledWithMatch(chromiumRunnerStub, {
-      customChromiumPrefs: sinon.match.instanceOf(Map),
+      customChromiumPrefs: sinon.match.object,
     });
 
     const { customChromiumPrefs } = chromiumRunnerStub.firstCall.args[0];

From a53d06ddb5409d548beb1c1b20acb7151e7e3650 Mon Sep 17 00:00:00 2001
From: PatrykKuniczak <p.kuniczak@gmail.com>
Date: Mon, 23 Mar 2026 09:28:00 +0100
Subject: [PATCH 06/14] Rename back DEFAULT_CHROMIUM_PREFS TO DEFAULT_PREFS

---
 src/extension-runners/chromium.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/extension-runners/chromium.js b/src/extension-runners/chromium.js
index dbb960fb3b..552e5b422b 100644
--- a/src/extension-runners/chromium.js
+++ b/src/extension-runners/chromium.js
@@ -29,7 +29,7 @@ export const DEFAULT_CHROME_FLAGS = ChromeLauncher.defaultFlags().filter(
   (flag) => !EXCLUDED_CHROME_FLAGS.includes(flag),
 );
 
-const DEFAULT_CHROMIUM_PREFS = { 'extensions.ui.developer_mode': true };
+const DEFAULT_PREFS = { 'extensions.ui.developer_mode': true };
 
 // This is a client for the Chrome Devtools protocol. The methods and results
 // are documented at https://chromedevtools.github.io/devtools-protocol/tot/
@@ -608,7 +608,7 @@ export class ChromiumExtensionRunner {
    */
   getPrefs() {
     return expandPrefs({
-      ...DEFAULT_CHROMIUM_PREFS,
+      ...DEFAULT_PREFS,
       ...this.params.customChromiumPrefs,
     });
   }

From 1135d21c0739ab33df50e9db5da4afd65bafef62 Mon Sep 17 00:00:00 2001
From: PatrykKuniczak <p.kuniczak@gmail.com>
Date: Mon, 23 Mar 2026 09:30:11 +0100
Subject: [PATCH 07/14] chore: Make expand-prefs.js more readable

---
 src/util/expand-prefs.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/util/expand-prefs.js b/src/util/expand-prefs.js
index 70fe95dd48..58018e4bfe 100644
--- a/src/util/expand-prefs.js
+++ b/src/util/expand-prefs.js
@@ -5,15 +5,19 @@
  */
 export default function expandPrefs(prefs) {
   const prefsMap = new Map();
+
   for (const [key, value] of Object.entries(prefs)) {
     let submap = prefsMap;
     const props = key.split('.');
     const lastProp = props.pop();
+
     for (const prop of props) {
       if (!submap.has(prop)) {
         submap.set(prop, new Map());
       }
+
       submap = submap.get(prop);
+
       if (!(submap instanceof Map)) {
         throw new Error(
           `Cannot set ${key} because a value already exists at ${prop}`,

From d261160da7b6b0ef39b388c126d33ef52e5834b8 Mon Sep 17 00:00:00 2001
From: PatrykKuniczak <p.kuniczak@gmail.com>
Date: Mon, 23 Mar 2026 09:33:59 +0100
Subject: [PATCH 08/14] revert: Imports order of program.js

---
 src/program.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/program.js b/src/program.js
index 711bdc9345..d7c1414c3e 100644
--- a/src/program.js
+++ b/src/program.js
@@ -10,15 +10,15 @@ import { Parser as yargsParser } from 'yargs/helpers';
 import defaultCommands from './cmd/index.js';
 import { UsageError } from './errors.js';
 import {
-  consoleStream as defaultLogStream,
   createLogger,
+  consoleStream as defaultLogStream,
 } from './util/logger.js';
 import { coerceCLICustomPreference } from './firefox/preferences.js';
 import { checkForUpdates as defaultUpdateChecker } from './util/updates.js';
 import {
-  applyConfigToArgv as defaultApplyConfigToArgv,
   discoverConfigFiles as defaultConfigDiscovery,
   loadJSConfigFile as defaultLoadJSConfigFile,
+  applyConfigToArgv as defaultApplyConfigToArgv,
 } from './config.js';
 
 const log = createLogger(import.meta.url);

From 2cb6ec7595161e9ff9847694e4d0ffe0e09296b7 Mon Sep 17 00:00:00 2001
From: Patryk Kuniczak <p.kuniczak@gmail.com>
Date: Thu, 23 Apr 2026 14:41:02 +0200
Subject: [PATCH 09/14] Update src/extension-runners/chromium.js

Co-authored-by: Rob Wu <rob@robwu.nl>
---
 src/extension-runners/chromium.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/extension-runners/chromium.js b/src/extension-runners/chromium.js
index 552e5b422b..f04faff69a 100644
--- a/src/extension-runners/chromium.js
+++ b/src/extension-runners/chromium.js
@@ -334,6 +334,7 @@ export class ChromiumExtensionRunner {
       logLevel: this.params.verbose ? 'verbose' : 'silent',
       // Ignore default flags to keep the extension enabled.
       ignoreDefaultFlags: true,
+      prefs: this.getPrefs(),
     });
     this.cdp = new ChromeDevtoolsProtocolClient(this.chromiumInstance);
 

From 05c58933a4e667d6f552c7ac67c46f224b879e46 Mon Sep 17 00:00:00 2001
From: PatrykKuniczak <p.kuniczak@gmail.com>
Date: Thu, 23 Apr 2026 15:22:32 +0200
Subject: [PATCH 10/14] Add tests for enabling and overriding developer_mode in
 Chromium prefs

---
 .../test-extension-runners/test.chromium.js   | 40 ++++++++++++++++++-
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/tests/unit/test-extension-runners/test.chromium.js b/tests/unit/test-extension-runners/test.chromium.js
index 012cbbb9f5..e19a2e62c1 100644
--- a/tests/unit/test-extension-runners/test.chromium.js
+++ b/tests/unit/test-extension-runners/test.chromium.js
@@ -70,6 +70,28 @@ function prepareExtensionRunnerParams(
 }
 
 describe('util/extension-runners/chromium', async () => {
+  describe('developer_mode pref', () => {
+    it('defaults extensions.ui.developer_mode to true', async () => {
+      const { params } = prepareExtensionRunnerParams();
+      const runnerInstance = new ChromiumExtensionRunner(params);
+      const prefs = runnerInstance.getPrefs();
+      assert.propertyVal(prefs.extensions.ui, 'developer_mode', true);
+    });
+
+    it('allows overriding extensions.ui.developer_mode to false', async () => {
+      const { params } = prepareExtensionRunnerParams({
+        params: {
+          customChromiumPrefs: {
+            'extensions.ui.developer_mode': false,
+          },
+        },
+      });
+      const runnerInstance = new ChromiumExtensionRunner(params);
+      const prefs = runnerInstance.getPrefs();
+      assert.propertyVal(prefs.extensions.ui, 'developer_mode', false);
+    });
+  });
+
   it('uses the expected chrome flags', () => {
     // Flags from chrome-launcher v0.14.0
     const expectedFlags = [
@@ -120,6 +142,13 @@ describe('util/extension-runners/chromium', async () => {
         '--disable-blink-features=AutomationControlled',
       ],
       startingUrl: undefined,
+      prefs: {
+        extensions: {
+          ui: {
+            developer_mode: true,
+          },
+        },
+      },
     });
 
     await runnerInstance.exit();
@@ -603,7 +632,7 @@ describe('util/extension-runners/chromium', async () => {
   });
 
   describe('getPrefs', () => {
-    it('merges default and custom preferences from an object', () => {
+    it('merges default and custom preferences from an object and passes them to the launcher', async () => {
       const { params } = prepareExtensionRunnerParams({
         params: {
           customChromiumPrefs: {
@@ -615,7 +644,7 @@ describe('util/extension-runners/chromium', async () => {
 
       const runnerInstance = new ChromiumExtensionRunner(params);
 
-      assert.deepEqual(runnerInstance.getPrefs(), {
+      const expectedPrefs = {
         extensions: {
           ui: {
             developer_mode: false,
@@ -626,6 +655,13 @@ describe('util/extension-runners/chromium', async () => {
             color: 'dark',
           },
         },
+      };
+
+      assert.deepEqual(runnerInstance.getPrefs(), expectedPrefs);
+
+      await runnerInstance.run();
+      sinon.assert.calledWithMatch(params.chromiumLaunch, {
+        prefs: expectedPrefs,
       });
     });
   });

From da15bcac870c364908574cf03cd29777c56fe833 Mon Sep 17 00:00:00 2001
From: Patryk Kuniczak <p.kuniczak@gmail.com>
Date: Thu, 23 Apr 2026 20:34:36 +0200
Subject: [PATCH 11/14] Update
 tests/unit/test-extension-runners/test.chromium.js

Co-authored-by: Rob Wu <rob@robwu.nl>
---
 tests/unit/test-extension-runners/test.chromium.js | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/tests/unit/test-extension-runners/test.chromium.js b/tests/unit/test-extension-runners/test.chromium.js
index e19a2e62c1..723fd2e783 100644
--- a/tests/unit/test-extension-runners/test.chromium.js
+++ b/tests/unit/test-extension-runners/test.chromium.js
@@ -74,8 +74,15 @@ describe('util/extension-runners/chromium', async () => {
     it('defaults extensions.ui.developer_mode to true', async () => {
       const { params } = prepareExtensionRunnerParams();
       const runnerInstance = new ChromiumExtensionRunner(params);
-      const prefs = runnerInstance.getPrefs();
-      assert.propertyVal(prefs.extensions.ui, 'developer_mode', true);
+      await runnerInstance.run();
+      sinon.assert.calledWithMatch(params.chromiumLaunch, {
+        prefs: {
+          ui: {
+            developer_mode: true,
+          },
+        },
+      });
+      await runnerInstance.exit();
     });
 
     it('allows overriding extensions.ui.developer_mode to false', async () => {

From 649c5e3afed558c28bf55e5d3de408f55c407811 Mon Sep 17 00:00:00 2001
From: PatrykKuniczak <p.kuniczak@gmail.com>
Date: Thu, 23 Apr 2026 20:39:23 +0200
Subject: [PATCH 12/14] remove unnecessary test and move `default extensions.ui
 ...` test into `getPrefs` describe

---
 .../test-extension-runners/test.chromium.js   | 43 ++++++-------------
 1 file changed, 14 insertions(+), 29 deletions(-)

diff --git a/tests/unit/test-extension-runners/test.chromium.js b/tests/unit/test-extension-runners/test.chromium.js
index 723fd2e783..70bc7fb061 100644
--- a/tests/unit/test-extension-runners/test.chromium.js
+++ b/tests/unit/test-extension-runners/test.chromium.js
@@ -70,35 +70,6 @@ function prepareExtensionRunnerParams(
 }
 
 describe('util/extension-runners/chromium', async () => {
-  describe('developer_mode pref', () => {
-    it('defaults extensions.ui.developer_mode to true', async () => {
-      const { params } = prepareExtensionRunnerParams();
-      const runnerInstance = new ChromiumExtensionRunner(params);
-      await runnerInstance.run();
-      sinon.assert.calledWithMatch(params.chromiumLaunch, {
-        prefs: {
-          ui: {
-            developer_mode: true,
-          },
-        },
-      });
-      await runnerInstance.exit();
-    });
-
-    it('allows overriding extensions.ui.developer_mode to false', async () => {
-      const { params } = prepareExtensionRunnerParams({
-        params: {
-          customChromiumPrefs: {
-            'extensions.ui.developer_mode': false,
-          },
-        },
-      });
-      const runnerInstance = new ChromiumExtensionRunner(params);
-      const prefs = runnerInstance.getPrefs();
-      assert.propertyVal(prefs.extensions.ui, 'developer_mode', false);
-    });
-  });
-
   it('uses the expected chrome flags', () => {
     // Flags from chrome-launcher v0.14.0
     const expectedFlags = [
@@ -639,6 +610,20 @@ describe('util/extension-runners/chromium', async () => {
   });
 
   describe('getPrefs', () => {
+    it('check if default extensions.ui.developer_mode is true', async () => {
+      const { params } = prepareExtensionRunnerParams();
+      const runnerInstance = new ChromiumExtensionRunner(params);
+      await runnerInstance.run();
+      sinon.assert.calledWithMatch(params.chromiumLaunch, {
+        prefs: {
+          ui: {
+            developer_mode: true,
+          },
+        },
+      });
+      await runnerInstance.exit();
+    });
+
     it('merges default and custom preferences from an object and passes them to the launcher', async () => {
       const { params } = prepareExtensionRunnerParams({
         params: {

From 48151b2ffbba3464337d84c572af8707e713b521 Mon Sep 17 00:00:00 2001
From: PatrykKuniczak <p.kuniczak@gmail.com>
Date: Thu, 23 Apr 2026 20:41:15 +0200
Subject: [PATCH 13/14] reorder `check if default extensions.ui ...` test

---
 .../test-extension-runners/test.chromium.js   | 28 +++++++++----------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/tests/unit/test-extension-runners/test.chromium.js b/tests/unit/test-extension-runners/test.chromium.js
index 70bc7fb061..4a10977474 100644
--- a/tests/unit/test-extension-runners/test.chromium.js
+++ b/tests/unit/test-extension-runners/test.chromium.js
@@ -102,6 +102,20 @@ describe('util/extension-runners/chromium', async () => {
     assert.notInclude(DEFAULT_CHROME_FLAGS, '--disable-extensions');
   });
 
+  it('check if default extensions.ui.developer_mode is true', async () => {
+    const { params } = prepareExtensionRunnerParams();
+    const runnerInstance = new ChromiumExtensionRunner(params);
+    await runnerInstance.run();
+    sinon.assert.calledWithMatch(params.chromiumLaunch, {
+      prefs: {
+        ui: {
+          developer_mode: true,
+        },
+      },
+    });
+    await runnerInstance.exit();
+  });
+
   it('installs and runs the extension', async () => {
     const { params, fakeChromeInstance } = prepareExtensionRunnerParams();
     const runnerInstance = new ChromiumExtensionRunner(params);
@@ -610,20 +624,6 @@ describe('util/extension-runners/chromium', async () => {
   });
 
   describe('getPrefs', () => {
-    it('check if default extensions.ui.developer_mode is true', async () => {
-      const { params } = prepareExtensionRunnerParams();
-      const runnerInstance = new ChromiumExtensionRunner(params);
-      await runnerInstance.run();
-      sinon.assert.calledWithMatch(params.chromiumLaunch, {
-        prefs: {
-          ui: {
-            developer_mode: true,
-          },
-        },
-      });
-      await runnerInstance.exit();
-    });
-
     it('merges default and custom preferences from an object and passes them to the launcher', async () => {
       const { params } = prepareExtensionRunnerParams({
         params: {

From 6ea8fcea58ca73742a549db1ea63d46fda243188 Mon Sep 17 00:00:00 2001
From: PatrykKuniczak <p.kuniczak@gmail.com>
Date: Thu, 23 Apr 2026 20:44:45 +0200
Subject: [PATCH 14/14] fix: `check if default extensions.ui ...` test expected
 params

---
 tests/unit/test-extension-runners/test.chromium.js | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tests/unit/test-extension-runners/test.chromium.js b/tests/unit/test-extension-runners/test.chromium.js
index 4a10977474..cfa5b3a81c 100644
--- a/tests/unit/test-extension-runners/test.chromium.js
+++ b/tests/unit/test-extension-runners/test.chromium.js
@@ -108,8 +108,10 @@ describe('util/extension-runners/chromium', async () => {
     await runnerInstance.run();
     sinon.assert.calledWithMatch(params.chromiumLaunch, {
       prefs: {
-        ui: {
-          developer_mode: true,
+        extensions: {
+          ui: {
+            developer_mode: true,
+          },
         },
       },
     });