diff --git a/admin/presets/tests/helper_test.php b/admin/presets/tests/helper_test.php
index f0e39c1ed97..3207c735276 100644
--- a/admin/presets/tests/helper_test.php
+++ b/admin/presets/tests/helper_test.php
@@ -364,7 +364,7 @@ class helper_test extends \advanced_testcase {
                 'preset' => 'unexisting',
             ],
             'Valid XML file' => [
-                'preset' => __DIR__ . '/fixtures/import_settings_plugins.xml',
+                'preset' => self::get_fixture_path(__NAMESPACE__, 'import_settings_plugins.xml'),
                 'settings' => [
                     'allowemojipicker' => 1,
                     'enableportfolios' => 1,
@@ -377,7 +377,7 @@ class helper_test extends \advanced_testcase {
                 ],
             ],
             'Invalid XML file' => [
-                'preset' => __DIR__ . '/fixtures/invalid_xml_file.xml',
+                'preset' => self::get_fixture_path(__NAMESPACE__, 'invalid_xml_file.xml'),
             ],
             'Unexisting XML file' => [
                 'preset' => __DIR__ . '/fixtures/unexisting.xml',
diff --git a/admin/presets/tests/manager_test.php b/admin/presets/tests/manager_test.php
index 2ab19814ebc..642f04fcee4 100644
--- a/admin/presets/tests/manager_test.php
+++ b/admin/presets/tests/manager_test.php
@@ -537,19 +537,25 @@ class manager_test extends \advanced_testcase {
                 'expectedpreset' => false,
             ],
             'Import settings and plugins from a valid XML file' => [
-                'filecontents' => file_get_contents(__DIR__ . '/fixtures/import_settings_plugins.xml'),
+                'filecontents' => file_get_contents(
+                    filename: self::get_fixture_path(__NAMESPACE__, 'import_settings_plugins.xml')
+                ),
                 'expectedpreset' => true,
                 'expectedsettings' => true,
                 'expectedplugins' => true,
             ],
             'Import only settings from a valid XML file' => [
-                'filecontents' => file_get_contents(__DIR__ . '/fixtures/import_settings.xml'),
+                'filecontents' => file_get_contents(
+                    filename: self::get_fixture_path(__NAMESPACE__, 'import_settings.xml')
+                ),
                 'expectedpreset' => true,
                 'expectedsettings' => true,
                 'expectedplugins' => false,
             ],
             'Import settings and plugins from a valid XML file with Starter name, which will be marked as non-core' => [
-                'filecontents' => file_get_contents(__DIR__ . '/fixtures/import_starter_name.xml'),
+                'filecontents' => file_get_contents(
+                    filename: self::get_fixture_path(__NAMESPACE__, 'import_starter_name.xml')
+                ),
                 'expectedpreset' => true,
                 'expectedsettings' => true,
                 'expectedplugins' => true,
@@ -558,7 +564,9 @@ class manager_test extends \advanced_testcase {
                 'expectedpresetname' => 'Starter',
             ],
             'Import settings from an invalid XML file' => [
-                'filecontents' => file_get_contents(__DIR__ . '/fixtures/invalid_xml_file.xml'),
+                'filecontents' => file_get_contents(
+                    filename: self::get_fixture_path(__NAMESPACE__, 'invalid_xml_file.xml')
+                ),
                 'expectedpreset' => false,
                 'expectedsettings' => false,
                 'expectedplugins' => false,
@@ -566,20 +574,26 @@ class manager_test extends \advanced_testcase {
                 'expectedexception' => \Exception::class,
             ],
             'Import unexisting settings category' => [
-                'filecontents' => file_get_contents(__DIR__ . '/fixtures/unexisting_category.xml'),
+                'filecontents' => file_get_contents(
+                    filename: self::get_fixture_path(__NAMESPACE__, 'unexisting_category.xml')
+                ),
                 'expectedpreset' => false,
                 'expectedsettings' => false,
                 'expectedplugins' => false,
             ],
             'Import unexisting setting' => [
-                'filecontents' => file_get_contents(__DIR__ . '/fixtures/unexisting_setting.xml'),
+                'filecontents' => file_get_contents(
+                    filename: self::get_fixture_path(__NAMESPACE__, 'unexisting_setting.xml')
+                ),
                 'expectedpreset' => false,
                 'expectedsettings' => false,
                 'expectedplugins' => false,
                 'expecteddebugging' => true,
             ],
             'Import valid settings with one unexisting setting too' => [
-                'filecontents' => file_get_contents(__DIR__ . '/fixtures/import_settings_with_unexisting_setting.xml'),
+                'filecontents' => file_get_contents(
+                    filename: self::get_fixture_path(__NAMESPACE__, 'import_settings_with_unexisting_setting.xml'),
+                ),
                 'expectedpreset' => true,
                 'expectedsettings' => false,
                 'expectedplugins' => false,
diff --git a/admin/roles/tests/preset_test.php b/admin/roles/tests/preset_test.php
index bc18626b12f..bc7b32c15fe 100644
--- a/admin/roles/tests/preset_test.php
+++ b/admin/roles/tests/preset_test.php
@@ -84,7 +84,7 @@ class preset_test extends \advanced_testcase {
     public function test_mixed_levels(): void {
         // The problem here is that we cannot guarantee plugin contexts
         // have unique short names, so we have to also support level numbers.
-        $xml = file_get_contents(__DIR__ . '/fixtures/mixed_levels.xml');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'mixed_levels.xml'));
         $this->assertTrue(\core_role_preset::is_valid_preset($xml));
 
         $preset = \core_role_preset::parse_preset($xml);
diff --git a/admin/tool/behat/tests/manager_util_test.php b/admin/tool/behat/tests/manager_util_test.php
index 5bb6627231c..35ff061ffc4 100644
--- a/admin/tool/behat/tests/manager_util_test.php
+++ b/admin/tool/behat/tests/manager_util_test.php
@@ -107,11 +107,11 @@ class manager_util_test extends \advanced_testcase {
      */
     private function get_behat_config_util($behatconfigutil, $notheme = false) {
         // Create a map of arguments to return values.
-        $map = array(
-            array('withfeatures', __DIR__.'/fixtures/theme/withfeatures'),
-            array('nofeatures', __DIR__.'/fixtures/theme/nofeatures'),
-            array('defaulttheme', __DIR__.'/fixtures/theme/defaulttheme'),
-        );
+        $map = [
+            ['withfeatures', self::get_fixture_path(__NAMESPACE__, 'theme/withfeatures')],
+            ['nofeatures', self::get_fixture_path(__NAMESPACE__, 'theme/nofeatures')],
+            ['defaulttheme', self::get_fixture_path(__NAMESPACE__, 'theme/defaulttheme')],
+        ];
         // List of themes is const for test.
         if ($notheme) {
             $themelist = array('defaulttheme');
diff --git a/admin/tool/lpimportcsv/tests/import_test.php b/admin/tool/lpimportcsv/tests/import_test.php
index fafbef13e15..cc6ef990a6c 100644
--- a/admin/tool/lpimportcsv/tests/import_test.php
+++ b/admin/tool/lpimportcsv/tests/import_test.php
@@ -31,7 +31,9 @@ class import_test extends \advanced_testcase {
         $this->resetAfterTest(true);
         $this->setAdminUser();
 
-        $importer = new framework_importer(file_get_contents(__DIR__ . '/fixtures/example.csv'));
+        $importer = new framework_importer(
+            file_get_contents(self::get_fixture_path(__NAMESPACE__, 'example.csv')),
+        );
 
         $this->assertEquals('', $importer->get_error());
 
diff --git a/admin/tool/uploadcourse/tests/course_test.php b/admin/tool/uploadcourse/tests/course_test.php
index 70cdc183edf..5a40d5ed67f 100644
--- a/admin/tool/uploadcourse/tests/course_test.php
+++ b/admin/tool/uploadcourse/tests/course_test.php
@@ -967,8 +967,14 @@ class course_test extends \advanced_testcase {
         // Restore from a file, checking that the file takes priority over the templatecourse.
         $mode = tool_uploadcourse_processor::MODE_CREATE_NEW;
         $updatemode = tool_uploadcourse_processor::UPDATE_ALL_WITH_DATA_ONLY;
-        $data = array('shortname' => 'A1', 'backupfile' => __DIR__ . '/fixtures/backup.mbz',
-            'summary' => 'A', 'category' => 1, 'fullname' => 'A1', 'templatecourse' => $c1->shortname);
+        $data = [
+            'shortname' => 'A1',
+            'backupfile' => self::get_fixture_path(__NAMESPACE__, 'backup.mbz'),
+            'summary' => 'A',
+            'category' => 1,
+            'fullname' => 'A1',
+            'templatecourse' => $c1->shortname,
+        ];
         $co = new tool_uploadcourse_course($mode, $updatemode, $data);
         $this->assertTrue($co->prepare());
         $co->proceed();
@@ -986,8 +992,13 @@ class course_test extends \advanced_testcase {
         $this->assertTrue($found);
 
         // Restoring twice from the same file should work.
-        $data = array('shortname' => 'B1', 'backupfile' => __DIR__ . '/fixtures/backup.mbz',
-            'summary' => 'B', 'category' => 1, 'fullname' => 'B1');
+        $data = [
+            'shortname' => 'B1',
+            'backupfile' => self::get_fixture_path(__NAMESPACE__, 'backup.mbz'),
+            'summary' => 'B',
+            'category' => 1,
+            'fullname' => 'B1',
+        ];
         $co = new tool_uploadcourse_course($mode, $updatemode, $data);
         $this->assertTrue($co->prepare());
         $co->proceed();
@@ -1020,8 +1031,14 @@ class course_test extends \advanced_testcase {
 
         $mode = tool_uploadcourse_processor::MODE_CREATE_NEW;
         $updatemode = tool_uploadcourse_processor::UPDATE_ALL_WITH_DATA_ONLY;
-        $data = array('shortname' => 'A1', 'backupfile' => __DIR__ . '/fixtures/backup.mbz',
-            'summary' => 'A', 'category' => 1, 'fullname' => 'A1', 'templatecourse' => $c1->shortname);
+        $data = [
+            'shortname' => 'A1',
+            'backupfile' => self::get_fixture_path(__NAMESPACE__, 'backup.mbz'),
+            'summary' => 'A',
+            'category' => 1,
+            'fullname' => 'A1',
+            'templatecourse' => $c1->shortname,
+        ];
         $co = new tool_uploadcourse_course($mode, $updatemode, $data);
         $this->assertTrue($co->prepare());
         $co->proceed();
diff --git a/admin/tool/uploadcourse/tests/processor_test.php b/admin/tool/uploadcourse/tests/processor_test.php
index 9ad956d2114..2b4bcb540e5 100644
--- a/admin/tool/uploadcourse/tests/processor_test.php
+++ b/admin/tool/uploadcourse/tests/processor_test.php
@@ -110,11 +110,11 @@ class processor_test extends \advanced_testcase {
         $cir->load_csv_content($content, 'utf-8', 'comma');
         $cir->init();
 
-        $options = array(
+        $options = [
             'mode' => tool_uploadcourse_processor::MODE_CREATE_NEW,
-            'restorefile' => __DIR__ . '/fixtures/backup.mbz',
-            'templatecourse' => 'DoesNotExist'  // Restorefile takes priority.
-        );
+            'restorefile' => self::get_fixture_path(__NAMESPACE__, 'backup.mbz'),
+            'templatecourse' => 'DoesNotExist',  // Restorefile takes priority.
+        ];
         $defaults = array('category' => '1');
 
         $p = new tool_uploadcourse_processor($cir, $options, $defaults);
diff --git a/admin/tool/usertours/tests/helper_test.php b/admin/tool/usertours/tests/helper_test.php
index 2b118af6899..ddc7db3c78a 100644
--- a/admin/tool/usertours/tests/helper_test.php
+++ b/admin/tool/usertours/tests/helper_test.php
@@ -106,7 +106,7 @@ final class helper_test extends \advanced_testcase {
         \core\di::set(
             \core\hook\manager::class,
             \core\hook\manager::phpunit_get_instance([
-                'test_plugin1' => __DIR__ . '/fixtures/invalid_serverside_hook_fixture.php',
+                'test_plugin1' => self::get_fixture_path(__NAMESPACE__, 'invalid_serverside_hook_fixture.php'),
             ]),
         );
 
@@ -118,7 +118,7 @@ final class helper_test extends \advanced_testcase {
         \core\di::set(
             \core\hook\manager::class,
             \core\hook\manager::phpunit_get_instance([
-                'test_plugin1' => __DIR__ . '/fixtures/clientside_filter_for_serverside_hook.php',
+                'test_plugin1' => self::get_fixture_path(__NAMESPACE__, 'clientside_filter_for_serverside_hook.php'),
             ]),
         );
 
@@ -130,7 +130,7 @@ final class helper_test extends \advanced_testcase {
         \core\di::set(
             \core\hook\manager::class,
             \core\hook\manager::phpunit_get_instance([
-                'test_plugin1' => __DIR__ . '/fixtures/serverside_filter_for_clientside_hook.php',
+                'test_plugin1' => self::get_fixture_path(__NAMESPACE__, 'serverside_filter_for_clientside_hook.php'),
             ]),
         );
 
@@ -142,7 +142,7 @@ final class helper_test extends \advanced_testcase {
         \core\di::set(
             \core\hook\manager::class,
             \core\hook\manager::phpunit_get_instance([
-                'test_plugin1' => __DIR__ . '/fixtures/hook_fixtures.php',
+                'test_plugin1' => self::get_fixture_path(__NAMESPACE__, 'hook_fixtures.php'),
             ]),
         );
 
@@ -175,7 +175,7 @@ final class helper_test extends \advanced_testcase {
         \core\di::set(
             \core\hook\manager::class,
             \core\hook\manager::phpunit_get_instance([
-                'test_plugin1' => __DIR__ . '/fixtures/invalid_clientside_hook_fixture.php',
+                'test_plugin1' => self::get_fixture_path(__NAMESPACE__, 'invalid_clientside_hook_fixture.php'),
             ]),
         );
 
diff --git a/analytics/tests/analysis_test.php b/analytics/tests/analysis_test.php
index 5d6fa8804fc..c9e7db37115 100644
--- a/analytics/tests/analysis_test.php
+++ b/analytics/tests/analysis_test.php
@@ -30,7 +30,7 @@ class analysis_test extends \advanced_testcase {
      * @return null
      */
     public function test_fill_firstanalyses_cache(): void {
-        require_once(__DIR__ . '/fixtures/test_timesplitting_upcoming_seconds.php');
+        require_once(self::get_fixture_path(__NAMESPACE__, 'test_timesplitting_upcoming_seconds.php'));
         $this->resetAfterTest();
 
         $modelid = 1;
diff --git a/course/tests/course_image_cache_test.php b/course/tests/course_image_cache_test.php
index 2a825e7dad0..ce0a9cef2f2 100644
--- a/course/tests/course_image_cache_test.php
+++ b/course/tests/course_image_cache_test.php
@@ -125,7 +125,9 @@ class course_image_cache_test extends \advanced_testcase {
         $cache = course_image::get_instance_for_cache(new cache_definition());
 
         // Create course without one image.
-        $draftid1 = $this->fill_draft_area(['filename1.jpg' => file_get_contents(__DIR__ . '/fixtures/image.jpg')]);
+        $draftid1 = $this->fill_draft_area([
+            'filename1.jpg' => file_get_contents(self::get_fixture_path(__NAMESPACE__, 'image.jpg')),
+        ]);
         $course1 = $this->getDataGenerator()->create_course(['overviewfiles_filemanager' => $draftid1]);
         $expected = $this->build_expected_course_image_url($course1, 'filename1.jpg');
         $this->assertEquals($expected, $method->invokeArgs($cache, [$course1]));
@@ -140,8 +142,8 @@ class course_image_cache_test extends \advanced_testcase {
 
         // Create course with two image files.
         $draftid1 = $this->fill_draft_area([
-            'filename1.jpg' => file_get_contents(__DIR__ . '/fixtures/image.jpg'),
-            'filename2.jpg' => file_get_contents(__DIR__ . '/fixtures/image.jpg'),
+            'filename1.jpg' => file_get_contents(self::get_fixture_path(__NAMESPACE__, 'image.jpg')),
+            'filename2.jpg' => file_get_contents(self::get_fixture_path(__NAMESPACE__, 'image.jpg')),
         ]);
         $course1 = $this->getDataGenerator()->create_course(['overviewfiles_filemanager' => $draftid1]);
 
@@ -159,8 +161,8 @@ class course_image_cache_test extends \advanced_testcase {
         // Create course with two image files and one zip file.
         $draftid1 = $this->fill_draft_area([
             'filename1.zip' => 'Test file contents2',
-            'filename2.jpg' => file_get_contents(__DIR__ . '/fixtures/image.jpg'),
-            'filename3.jpg' => file_get_contents(__DIR__ . '/fixtures/image.jpg'),
+            'filename2.jpg' => file_get_contents(self::get_fixture_path(__NAMESPACE__, 'image.jpg')),
+            'filename3.jpg' => file_get_contents(self::get_fixture_path(__NAMESPACE__, 'image.jpg')),
         ]);
         $course1 = $this->getDataGenerator()->create_course(['overviewfiles_filemanager' => $draftid1]);
 
diff --git a/course/tests/course_summary_exporter_test.php b/course/tests/course_summary_exporter_test.php
index e95c7a77783..d697d6ad478 100644
--- a/course/tests/course_summary_exporter_test.php
+++ b/course/tests/course_summary_exporter_test.php
@@ -61,7 +61,7 @@ class course_summary_exporter_test extends \advanced_testcase {
             'filepath' => '/',
         ];
         $fs = get_file_storage();
-        $fs->create_file_from_string($filerecord, file_get_contents(__DIR__ . '/fixtures/image.jpg'));
+        $fs->create_file_from_string($filerecord, file_get_contents(self::get_fixture_path(__NAMESPACE__, 'image.jpg')));
         $course = $this->getDataGenerator()->create_course(['overviewfiles_filemanager' => $draftid]);
         $coursecontext = context_course::instance($course->id);
 
diff --git a/course/tests/externallib_test.php b/course/tests/externallib_test.php
index 0c4c8af2053..d72350c2922 100644
--- a/course/tests/externallib_test.php
+++ b/course/tests/externallib_test.php
@@ -2876,7 +2876,7 @@ final class externallib_test extends externallib_advanced_testcase {
             'filepath' => '/',
         ];
         $fs = get_file_storage();
-        $fs->create_file_from_pathname($filerecord, __DIR__ . '/fixtures/image.jpg');
+        $fs->create_file_from_pathname($filerecord, self::get_fixture_path('core_course', 'image.jpg'));
         $course2 = self::getDataGenerator()->create_course([
             'visible' => 0,
             'category' => $category2->id,
diff --git a/enrol/lti/tests/helper_test.php b/enrol/lti/tests/helper_test.php
index e1e99fdb6c6..479215224f2 100644
--- a/enrol/lti/tests/helper_test.php
+++ b/enrol/lti/tests/helper_test.php
@@ -479,11 +479,11 @@ class helper_test extends \advanced_testcase {
         $function = $helper->getMethod('set_xpath');
 
         $document = new \DOMDocument();
-        $document->load(realpath(__DIR__ . '/fixtures/input.xml'));
+        $document->load(realpath(self::get_fixture_path(__NAMESPACE__, 'input.xml')));
         $xpath = new \DOMXpath($document);
         $function->invokeArgs(null, [$xpath, $parameters]);
         $result = $document->saveXML();
-        $expected = file_get_contents(realpath(__DIR__ . '/fixtures/' . $expected));
+        $expected = file_get_contents(realpath(self::get_fixture_path(__NAMESPACE__, $expected)));
         $this->assertEquals($expected, $result);
     }
 
@@ -503,7 +503,7 @@ class helper_test extends \advanced_testcase {
         $function = $helper->getMethod('set_xpath');
 
         $document = new \DOMDocument();
-        $document->load(realpath(__DIR__ . '/fixtures/input.xml'));
+        $document->load(realpath(self::get_fixture_path(__NAMESPACE__, 'input.xml')));
         $xpath = new \DOMXpath($document);
 
         $this->expectException('coding_exception');
diff --git a/enrol/lti/tests/tool_provider_test.php b/enrol/lti/tests/tool_provider_test.php
index 7d8754614a0..874c44bdd22 100644
--- a/enrol/lti/tests/tool_provider_test.php
+++ b/enrol/lti/tests/tool_provider_test.php
@@ -206,7 +206,7 @@ class tool_provider_test extends \advanced_testcase {
         $consumer->consumerVersion = 'TEST CONSUMER INFO VERSION';
         $consumer->enabled = true;
         $consumer->protected = true;
-        $profilejson = file_get_contents(__DIR__ . '/fixtures/tool_consumer_profile.json');
+        $profilejson = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'tool_consumer_profile.json'));
         $consumer->profile = json_decode($profilejson);
         $consumer->save();
 
@@ -239,7 +239,7 @@ class tool_provider_test extends \advanced_testcase {
         $consumer->consumerVersion = 'TEST CONSUMER INFO VERSION';
         $consumer->enabled = true;
         $consumer->protected = true;
-        $profilejson = file_get_contents(__DIR__ . '/fixtures/tool_consumer_profile.json');
+        $profilejson = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'tool_consumer_profile.json'));
         $consumer->profile = json_decode($profilejson);
         $consumer->save();
 
diff --git a/h5p/tests/api_test.php b/h5p/tests/api_test.php
index b3fe6c3322d..ae497f4797b 100644
--- a/h5p/tests/api_test.php
+++ b/h5p/tests/api_test.php
@@ -287,7 +287,7 @@ class api_test extends \advanced_testcase {
 
         // Create the H5P data.
         $filename = 'find-the-words.h5p';
-        $path = __DIR__ . '/fixtures/' . $filename;
+        $path = self::get_fixture_path(__NAMESPACE__, $filename);
         $fakefile = helper::create_fake_stored_file_from_path($path);
         $config = (object)[
             'frame' => 1,
@@ -350,7 +350,7 @@ class api_test extends \advanced_testcase {
 
         // Create the original file.
         $filename = 'greeting-card.h5p';
-        $path = __DIR__ . '/fixtures/' . $filename;
+        $path = self::get_fixture_path(__NAMESPACE__, $filename);
         $originalfile = helper::create_fake_stored_file_from_path($path);
         $originalfilerecord = [
             'contextid' => $originalfile->get_contextid(),
@@ -492,7 +492,7 @@ class api_test extends \advanced_testcase {
 
         // Create the file.
         $filename = 'greeting-card.h5p';
-        $path = __DIR__ . '/fixtures/' . $filename;
+        $path = self::get_fixture_path(__NAMESPACE__, $filename);
         if ($filecomponent === 'contentbank') {
             $generator = $this->getDataGenerator()->get_plugin_generator('core_contentbank');
             $contents = $generator->generate_contentbank_data(
@@ -754,7 +754,7 @@ class api_test extends \advanced_testcase {
 
         // Create the H5P data.
         $filename = 'find-the-words.h5p';
-        $path = __DIR__ . '/fixtures/' . $filename;
+        $path = self::get_fixture_path(__NAMESPACE__, $filename);
         $fakefile = helper::create_fake_stored_file_from_path($path);
         $config = (object)[
             'frame' => 1,
@@ -812,7 +812,7 @@ class api_test extends \advanced_testcase {
 
         // Create the H5P data.
         $filename = 'find-the-words.h5p';
-        $path = __DIR__ . '/fixtures/' . $filename;
+        $path = self::get_fixture_path(__NAMESPACE__, $filename);
         $fakefile = helper::create_fake_stored_file_from_path($path);
         $config = (object)[
             'frame' => 1,
diff --git a/h5p/tests/editor_test.php b/h5p/tests/editor_test.php
index b04e5c6c070..b0aed637542 100644
--- a/h5p/tests/editor_test.php
+++ b/h5p/tests/editor_test.php
@@ -84,7 +84,7 @@ class editor_test extends advanced_testcase {
         // Add H5P content.
         // This is a valid .H5P file.
         $filename = 'find-the-words.h5p';
-        $path = __DIR__ . '/fixtures/' . $filename;
+        $path = self::get_fixture_path(__NAMESPACE__, $filename);
         $syscontext = \context_system::instance();
         $filerecord = [
             'contextid' => $syscontext->id,
diff --git a/h5p/tests/file_storage_test.php b/h5p/tests/file_storage_test.php
index 065f0e516c2..4ab8353dff6 100644
--- a/h5p/tests/file_storage_test.php
+++ b/h5p/tests/file_storage_test.php
@@ -475,7 +475,7 @@ class file_storage_test extends \advanced_testcase {
     public function test_saveFileFromZip(): void {
 
         $ziparchive = new zip_archive();
-        $path = __DIR__ . '/fixtures/h5ptest.zip';
+        $path = self::get_fixture_path(__NAMESPACE__, 'h5ptest.zip');
         $result = $ziparchive->open($path, file_archive::OPEN);
 
         $files = $ziparchive->list_files();
@@ -562,7 +562,7 @@ class file_storage_test extends \advanced_testcase {
         $admin = get_admin();
 
         // Prepare a valid .H5P file.
-        $path = __DIR__ . '/fixtures/'.$filename;
+        $path = self::get_fixture_path(__NAMESPACE__, $filename);
 
         // Libraries can be updated when the file has been created by admin, even when the current user is not the admin.
         $this->setUser($admin);
diff --git a/h5p/tests/framework_test.php b/h5p/tests/framework_test.php
index c7d2fc32df6..116c024b257 100644
--- a/h5p/tests/framework_test.php
+++ b/h5p/tests/framework_test.php
@@ -803,7 +803,7 @@ class framework_test extends \advanced_testcase {
         $this->getDataGenerator()->enrol_user($user->id, $course->id, 'student');
 
         // Create the .h5p file.
-        $path = __DIR__ . '/fixtures/h5ptest.zip';
+        $path = self::get_fixture_path(__NAMESPACE__, 'h5ptest.zip');
 
         // Admin and manager should have permission to update libraries.
         $file = helper::create_fake_stored_file_from_path($path, $admin->id, $contextsys);
@@ -860,7 +860,7 @@ class framework_test extends \advanced_testcase {
         $user = $this->getDataGenerator()->create_user();
 
         // The H5P file.
-        $path = __DIR__ . '/fixtures/h5ptest.zip';
+        $path = self::get_fixture_path(__NAMESPACE__, 'h5ptest.zip');
 
         // An error should be raised when it's called before initialitzing it.
         $this->expectException('coding_exception');
diff --git a/h5p/tests/helper_test.php b/h5p/tests/helper_test.php
index a257d04e246..b538bf49532 100644
--- a/h5p/tests/helper_test.php
+++ b/h5p/tests/helper_test.php
@@ -137,7 +137,7 @@ class helper_test extends \advanced_testcase {
         $this->setUser($user);
 
         // This is a valid .H5P file.
-        $path = __DIR__ . '/fixtures/greeting-card.h5p';
+        $path = self::get_fixture_path(__NAMESPACE__, 'greeting-card.h5p');
         $file = helper::create_fake_stored_file_from_path($path, (int)$user->id);
         $factory->get_framework()->set_file($file);
 
@@ -173,7 +173,7 @@ class helper_test extends \advanced_testcase {
         $this->setUser($user);
 
         // This is a valid .H5P file.
-        $path = __DIR__ . '/fixtures/greeting-card.h5p';
+        $path = self::get_fixture_path(__NAMESPACE__, 'greeting-card.h5p');
         $file = helper::create_fake_stored_file_from_path($path, (int)$user->id);
         $factory->get_framework()->set_file($file);
 
@@ -217,7 +217,7 @@ class helper_test extends \advanced_testcase {
         $this->setUser($user);
 
         // This is a valid .H5P file.
-        $path = __DIR__ . '/fixtures/guess-the-answer.h5p';
+        $path = self::get_fixture_path(__NAMESPACE__, 'guess-the-answer.h5p');
         $file = helper::create_fake_stored_file_from_path($path, (int)$user->id);
         $factory->get_framework()->set_file($file);
 
@@ -263,7 +263,7 @@ class helper_test extends \advanced_testcase {
         $this->setUser($user);
 
         // Prepare an invalid .H5P file.
-        $path = __DIR__ . '/fixtures/h5ptest.zip';
+        $path = self::get_fixture_path(__NAMESPACE__, 'h5ptest.zip');
         $file = helper::create_fake_stored_file_from_path($path, (int)$user->id);
         $factory->get_framework()->set_file($file);
         $config = (object)[
@@ -297,7 +297,7 @@ class helper_test extends \advanced_testcase {
         $admin = get_admin();
 
         // Prepare a valid .H5P file.
-        $path = __DIR__ . '/fixtures/greeting-card.h5p';
+        $path = self::get_fixture_path(__NAMESPACE__, 'greeting-card.h5p');
 
         // Files created by users can't be deployed.
         $file = helper::create_fake_stored_file_from_path($path, (int)$user->id);
@@ -335,7 +335,7 @@ class helper_test extends \advanced_testcase {
         $admin = get_admin();
 
         // Prepare a valid .H5P file.
-        $path = __DIR__ . '/fixtures/greeting-card.h5p';
+        $path = self::get_fixture_path(__NAMESPACE__, 'greeting-card.h5p');
 
         // Libraries can't be updated when the file has been created by users.
         $file = helper::create_fake_stored_file_from_path($path, (int)$user->id);
@@ -385,7 +385,7 @@ class helper_test extends \advanced_testcase {
         $this->assertCount(2, $messages->info);
 
         // When saving an invalid .h5p file, 6 errors should be raised.
-        $path = __DIR__ . '/fixtures/h5ptest.zip';
+        $path = self::get_fixture_path(__NAMESPACE__, 'h5ptest.zip');
         $file = helper::create_fake_stored_file_from_path($path);
         $factory->get_framework()->set_file($file);
         $config = (object)[
diff --git a/lib/tests/date_test.php b/lib/tests/date_test.php
index 98f4396cb90..99405ee69e1 100644
--- a/lib/tests/date_test.php
+++ b/lib/tests/date_test.php
@@ -126,7 +126,7 @@ class date_test extends advanced_testcase {
      * @covers ::normalise_timezone
      */
     public function test_windows_conversion(): void {
-        $file = __DIR__ . '/fixtures/timezonewindows.xml';
+        $file = self::get_fixture_path('core', 'timezonewindows.xml');
 
         $contents = file_get_contents($file);
         preg_match_all('/<mapZone other="([^"]+)" territory="001" type="([^"]+)"\/>/', $contents, $matches, PREG_SET_ORDER);
diff --git a/lib/tests/update_code_manager_test.php b/lib/tests/update_code_manager_test.php
index d5df6d54084..c223322037b 100644
--- a/lib/tests/update_code_manager_test.php
+++ b/lib/tests/update_code_manager_test.php
@@ -66,7 +66,7 @@ class update_code_manager_test extends \advanced_testcase {
 
     public function test_unzip_plugin_file(): void {
         $codeman = new \core\update\testable_code_manager();
-        $zipfilepath = __DIR__.'/fixtures/update_validator/zips/invalidroot.zip';
+        $zipfilepath = self::get_fixture_path(__NAMESPACE__, 'update_validator/zips/invalidroot.zip');
         $targetdir = make_request_directory();
         mkdir($targetdir.'/aaa_another');
 
@@ -102,13 +102,13 @@ class update_code_manager_test extends \advanced_testcase {
             }
         }
 
-        $zipfilepath = __DIR__.'/fixtures/update_validator/zips/bar.zip';
+        $zipfilepath = self::get_fixture_path(__NAMESPACE__, 'update_validator/zips/bar.zip');
         $files = $codeman->unzip_plugin_file($zipfilepath, $targetdir, 'bar');
     }
 
     public function test_unzip_plugin_file_multidir(): void {
         $codeman = new \core\update\testable_code_manager();
-        $zipfilepath = __DIR__.'/fixtures/update_validator/zips/multidir.zip';
+        $zipfilepath = self::get_fixture_path(__NAMESPACE__, 'update_validator/zips/multidir.zip');
         $targetdir = make_request_directory();
         // Attempting to rename the root folder if there are multiple ones should lead to exception.
         $this->expectException(\moodle_exception::class);
@@ -118,18 +118,18 @@ class update_code_manager_test extends \advanced_testcase {
     public function test_get_plugin_zip_root_dir(): void {
         $codeman = new \core\update\testable_code_manager();
 
-        $zipfilepath = __DIR__.'/fixtures/update_validator/zips/invalidroot.zip';
+        $zipfilepath = self::get_fixture_path(__NAMESPACE__, 'update_validator/zips/invalidroot.zip');
         $this->assertEquals('invalid-root', $codeman->get_plugin_zip_root_dir($zipfilepath));
 
-        $zipfilepath = __DIR__.'/fixtures/update_validator/zips/bar.zip';
+        $zipfilepath = self::get_fixture_path(__NAMESPACE__, 'update_validator/zips/bar.zip');
         $this->assertEquals('bar', $codeman->get_plugin_zip_root_dir($zipfilepath));
 
-        $zipfilepath = __DIR__.'/fixtures/update_validator/zips/multidir.zip';
+        $zipfilepath = self::get_fixture_path(__NAMESPACE__, 'update_validator/zips/multidir.zip');
         $this->assertSame(false, $codeman->get_plugin_zip_root_dir($zipfilepath));
     }
 
     public function test_list_plugin_folder_files(): void {
-        $fixtures = __DIR__.'/fixtures/update_validator/plugindir';
+        $fixtures = self::get_fixture_path(__NAMESPACE__, 'update_validator/plugindir');
         $codeman = new \core\update\testable_code_manager();
         $files = $codeman->list_plugin_folder_files($fixtures.'/foobar');
         $this->assertIsArray($files);
@@ -140,7 +140,7 @@ class update_code_manager_test extends \advanced_testcase {
     }
 
     public function test_zip_plugin_folder(): void {
-        $fixtures = __DIR__.'/fixtures/update_validator/plugindir';
+        $fixtures = self::get_fixture_path(__NAMESPACE__, 'update_validator/plugindir');
         $storage = make_request_directory();
         $codeman = new \core\update\testable_code_manager();
         $codeman->zip_plugin_folder($fixtures.'/foobar', $storage.'/foobar.zip');
@@ -159,7 +159,7 @@ class update_code_manager_test extends \advanced_testcase {
     }
 
     public function test_archiving_plugin_version(): void {
-        $fixtures = __DIR__.'/fixtures/update_validator/plugindir';
+        $fixtures = self::get_fixture_path(__NAMESPACE__, 'update_validator/plugindir');
         $codeman = new \core\update\testable_code_manager();
 
         $this->assertFalse($codeman->archive_plugin_version($fixtures.'/foobar', 'local_foobar', 0));
diff --git a/mod/book/tool/importhtml/tests/locallib_test.php b/mod/book/tool/importhtml/tests/locallib_test.php
index 56c1166f1e1..cff080ecef6 100644
--- a/mod/book/tool/importhtml/tests/locallib_test.php
+++ b/mod/book/tool/importhtml/tests/locallib_test.php
@@ -57,7 +57,7 @@ class locallib_test extends \advanced_testcase {
         $record->filename = 'chapters.zip';
 
         $fs = get_file_storage();
-        $file = $fs->create_file_from_pathname($record, __DIR__ . '/fixtures/chapters.zip');
+        $file = $fs->create_file_from_pathname($record, self::get_fixture_path(__NAMESPACE__, 'chapters.zip'));
 
         // Importing the chapters.
         $sink = $this->redirectEvents();
diff --git a/mod/data/tests/entries_export_test.php b/mod/data/tests/entries_export_test.php
index 0323fbe7f56..84cda6b9d4b 100644
--- a/mod/data/tests/entries_export_test.php
+++ b/mod/data/tests/entries_export_test.php
@@ -130,7 +130,7 @@ class entries_export_test extends \advanced_testcase {
         $includefiles = false;
         utils::data_exportdata($data->id, $fields, $selectedfields, $exporter, $currentgroup, $context,
             $exportuser, $exporttime, $exportapproval, $tags, $includefiles);
-        $this->assertEquals(file_get_contents(__DIR__ . '/fixtures/test_data_export_without_files.csv'),
+        $this->assertEquals(file_get_contents(self::get_fixture_path(__NAMESPACE__, 'test_data_export_without_files.csv')),
             $exporter->send_file(false));
 
         $this->assertEquals(1, $exporter->get_records_count());
@@ -158,7 +158,7 @@ class entries_export_test extends \advanced_testcase {
             // that the filenames in the csv file correspond to the names of the exported file.
             // It also verifies that files with identical file names in different fields (or records) will be numbered
             // automatically (samplefile.png, samplefile_1.png, ...).
-            'testexportfile.csv' => __DIR__ . '/fixtures/test_data_export_with_files.csv'
+            'testexportfile.csv' => self::get_fixture_path(__NAMESPACE__, 'test_data_export_with_files.csv'),
         ];
         for ($i = 0; $i < $ziparchive->count(); $i++) {
             // We here iterate over all files in the zip archive and check if their content is identical to the files
diff --git a/mod/data/tests/entries_import_test.php b/mod/data/tests/entries_import_test.php
index 8c2dd51d971..416207bd98a 100644
--- a/mod/data/tests/entries_import_test.php
+++ b/mod/data/tests/entries_import_test.php
@@ -104,7 +104,7 @@ final class entries_import_test extends \advanced_testcase {
             'teacher' => $teacher,
         ] = $this->get_test_data();
 
-        $importer = new csv_entries_importer(__DIR__ . '/fixtures/test_data_import.csv',
+        $importer = new csv_entries_importer(self::get_fixture_path(__NAMESPACE__, 'test_data_import.csv'),
             'test_data_import.csv');
         $importer->import_csv($cm, $data, 'UTF-8', 'comma');
 
@@ -136,7 +136,7 @@ final class entries_import_test extends \advanced_testcase {
             'student' => $student,
         ] = $this->get_test_data();
 
-        $importer = new csv_entries_importer(__DIR__ . '/fixtures/test_data_import_with_userdata.csv',
+        $importer = new csv_entries_importer(self::get_fixture_path(__NAMESPACE__, 'test_data_import_with_userdata.csv'),
             'test_data_import_with_userdata.csv');
         $importer->import_csv($cm, $data, 'UTF-8', 'comma');
 
@@ -177,7 +177,7 @@ final class entries_import_test extends \advanced_testcase {
         $fieldrecord->type = 'text';
         $generator->create_field($fieldrecord, $data);
 
-        $importer = new csv_entries_importer(__DIR__ . '/fixtures/test_data_import_with_field_username.csv',
+        $importer = new csv_entries_importer(self::get_fixture_path(__NAMESPACE__, 'test_data_import_with_field_username.csv'),
             'test_data_import_with_field_username.csv');
         $importer->import_csv($cm, $data, 'UTF-8', 'comma');
 
@@ -239,7 +239,7 @@ final class entries_import_test extends \advanced_testcase {
         $fieldrecord->type = 'text';
         $generator->create_field($fieldrecord, $data);
 
-        $importer = new csv_entries_importer(__DIR__ . '/fixtures/test_data_import_with_userdata.csv',
+        $importer = new csv_entries_importer(self::get_fixture_path(__NAMESPACE__, 'test_data_import_with_userdata.csv'),
             'test_data_import_with_userdata.csv');
         $importer->import_csv($cm, $data, 'UTF-8', 'comma');
 
@@ -298,7 +298,7 @@ final class entries_import_test extends \advanced_testcase {
 
         $this->setUser($testdata[$user]);
 
-        $importer = new csv_entries_importer(__DIR__ . '/fixtures/test_data_import.csv', 'test_data_import.csv');
+        $importer = new csv_entries_importer(self::get_fixture_path(__NAMESPACE__, 'test_data_import.csv'), 'test_data_import.csv');
         $importer->import_csv($cm, $data, 'UTF-8', 'comma');
 
         $records = $this->get_data_records($data->id);
@@ -331,7 +331,7 @@ final class entries_import_test extends \advanced_testcase {
 
         $this->setUser($testdata[$user]);
 
-        $importer = new csv_entries_importer(__DIR__ . '/fixtures/test_data_import_with_approved.csv',
+        $importer = new csv_entries_importer(self::get_fixture_path(__NAMESPACE__, 'test_data_import_with_approved.csv'),
             'test_data_import_with_approved.csv');
         $importer->import_csv($cm, $data, 'UTF-8', 'comma');
 
@@ -348,13 +348,13 @@ final class entries_import_test extends \advanced_testcase {
             'cm' => $cm,
         ] = $this->get_test_data();
 
-        $importer = new csv_entries_importer(__DIR__ . '/fixtures/test_data_import_with_files.zip',
+        $importer = new csv_entries_importer(self::get_fixture_path(__NAMESPACE__, 'test_data_import_with_files.zip'),
             'test_data_import_with_files.zip');
         $importer->import_csv($cm, $data, 'UTF-8', 'comma');
 
         $records = $this->get_data_records($data->id);
         $ziparchive = new zip_archive();
-        $ziparchive->open(__DIR__ . '/fixtures/test_data_import_with_files.zip');
+        $ziparchive->open(self::get_fixture_path(__NAMESPACE__, 'test_data_import_with_files.zip'));
 
         $importedcontent = array_values($records)[0]->items;
         $this->assertEquals(17, $importedcontent['ID']->content);
@@ -395,13 +395,13 @@ final class entries_import_test extends \advanced_testcase {
             'cm' => $cm,
         ] = $this->get_test_data();
 
-        $importer = new csv_entries_importer(__DIR__ . '/fixtures/test_data_import_with_files_missing_file.zip',
+        $importer = new csv_entries_importer(self::get_fixture_path(__NAMESPACE__, 'test_data_import_with_files_missing_file.zip'),
             'test_data_import_with_files_missing_file.zip');
         $importer->import_csv($cm, $data, 'UTF-8', 'comma');
 
         $records = $this->get_data_records($data->id);
         $ziparchive = new zip_archive();
-        $ziparchive->open(__DIR__ . '/fixtures/test_data_import_with_files_missing_file.zip');
+        $ziparchive->open(self::get_fixture_path(__NAMESPACE__, 'test_data_import_with_files_missing_file.zip'));
 
         $importedcontent = array_values($records)[0]->items;
         $this->assertEquals(17, $importedcontent['ID']->content);
diff --git a/mod/quiz/accessrule/seb/tests/access_manager_test.php b/mod/quiz/accessrule/seb/tests/access_manager_test.php
index b07acd4dd45..daf59d45c99 100644
--- a/mod/quiz/accessrule/seb/tests/access_manager_test.php
+++ b/mod/quiz/accessrule/seb/tests/access_manager_test.php
@@ -325,7 +325,7 @@ class access_manager_test extends \advanced_testcase {
         $this->quiz = $this->create_test_quiz($this->course, settings_provider::USE_SEB_CONFIG_MANUALLY);
         $quizsettings = seb_quiz_settings::get_record(['quizid' => $this->quiz->id]);
         $quizsettings->set('requiresafeexambrowser', settings_provider::USE_SEB_UPLOAD_CONFIG); // Doesn't check basic header.
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
         $this->create_module_test_file($xml, $this->quiz->cmid);
         $quizsettings->save();
         $accessmanager = $this->get_access_manager();
diff --git a/mod/quiz/accessrule/seb/tests/backup_restore_test.php b/mod/quiz/accessrule/seb/tests/backup_restore_test.php
index 3a6cb0e3db5..63cd799f63e 100644
--- a/mod/quiz/accessrule/seb/tests/backup_restore_test.php
+++ b/mod/quiz/accessrule/seb/tests/backup_restore_test.php
@@ -201,7 +201,7 @@ class backup_restore_test extends \advanced_testcase {
 
         $expected = seb_quiz_settings::get_record(['quizid' => $this->quiz->id]);
         $expected->set('requiresafeexambrowser', settings_provider::USE_SEB_UPLOAD_CONFIG);
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
         $this->create_module_test_file($xml, $this->quiz->cmid);
         $expected->save();
 
diff --git a/mod/quiz/accessrule/seb/tests/config_key_test.php b/mod/quiz/accessrule/seb/tests/config_key_test.php
index 7fcc0ed40c0..351c3fb167f 100644
--- a/mod/quiz/accessrule/seb/tests/config_key_test.php
+++ b/mod/quiz/accessrule/seb/tests/config_key_test.php
@@ -53,7 +53,7 @@ class config_key_test extends \advanced_testcase {
      * @dataProvider real_ck_hash_provider
      */
     public function test_config_key_hash_is_derived_correctly($config, $hash): void {
-        $xml = file_get_contents(__DIR__ . '/fixtures/' . $config);
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, $config));
         $derivedhash = config_key::generate($xml)->get_hash();
         $this->assertEquals($hash, $derivedhash);
     }
@@ -62,8 +62,8 @@ class config_key_test extends \advanced_testcase {
      * Check that the Config Key hash is not altered if the originatorVersion is present in the XML or not.
      */
     public function test_presence_of_originator_version_does_not_effect_hash(): void {
-        $xmlwithoriginatorversion = file_get_contents(__DIR__ . '/fixtures/simpleunencrypted.seb');
-        $xmlwithoutoriginatorversion = file_get_contents(__DIR__ . '/fixtures/simpleunencryptedwithoutoriginator.seb');
+        $xmlwithoriginatorversion = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'simpleunencrypted.seb'));
+        $xmlwithoutoriginatorversion = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'simpleunencryptedwithoutoriginator.seb'));
         $hashwithorigver = config_key::generate($xmlwithoriginatorversion)->get_hash();
         $hashwithoutorigver = config_key::generate($xmlwithoutoriginatorversion)->get_hash();
         $this->assertEquals($hashwithorigver, $hashwithoutorigver);
diff --git a/mod/quiz/accessrule/seb/tests/property_list_test.php b/mod/quiz/accessrule/seb/tests/property_list_test.php
index bcb513ef187..ab23fe88e8e 100644
--- a/mod/quiz/accessrule/seb/tests/property_list_test.php
+++ b/mod/quiz/accessrule/seb/tests/property_list_test.php
@@ -235,11 +235,11 @@ class property_list_test extends \advanced_testcase {
      * Test that the xml is exported to JSON from a real SEB config file. Expected JSON extracted from SEB logs.
      */
     public function test_export_to_json_full_file(): void {
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted_mac_001.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted_mac_001.seb'));
         $plist = new property_list($xml);
         $plist->delete_element('originatorVersion'); // JSON should not contain originatorVersion key.
         $generatedjson = $plist->to_json();
-        $json = trim(file_get_contents(__DIR__ . '/fixtures/JSON_unencrypted_mac_001.txt'));
+        $json = trim(file_get_contents(self::get_fixture_path(__NAMESPACE__, 'JSON_unencrypted_mac_001.txt')));
         $this->assertEquals($json, $generatedjson);
     }
 
diff --git a/mod/quiz/accessrule/seb/tests/quiz_settings_test.php b/mod/quiz/accessrule/seb/tests/quiz_settings_test.php
index b70988aeb7a..feef8a5a21d 100644
--- a/mod/quiz/accessrule/seb/tests/quiz_settings_test.php
+++ b/mod/quiz/accessrule/seb/tests/quiz_settings_test.php
@@ -499,7 +499,7 @@ class quiz_settings_test extends \advanced_testcase {
         $this->save_settings_with_optional_template($quizsettings, settings_provider::USE_SEB_TEMPLATE, $templateid);
 
         // Case for USE_SEB_UPLOAD_CONFIG, ensure template id reverts to 0.
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
         $this->create_module_test_file($xml, $this->quiz->cmid);
         $this->save_settings_with_optional_template($quizsettings, settings_provider::USE_SEB_UPLOAD_CONFIG);
         $quizsettings = seb_quiz_settings::get_record(['quizid' => $this->quiz->id]);
@@ -709,7 +709,7 @@ class quiz_settings_test extends \advanced_testcase {
         $this->assertNull($quizsettings->get_config());
 
         $quizsettings->set('requiresafeexambrowser', settings_provider::USE_SEB_UPLOAD_CONFIG);
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
         $this->create_module_test_file($xml, $this->quiz->cmid);
         $quizsettings->save();
         $quizsettings = seb_quiz_settings::get_record(['quizid' => $this->quiz->id]);
diff --git a/mod/quiz/accessrule/seb/tests/rule_test.php b/mod/quiz/accessrule/seb/tests/rule_test.php
index 9a9305bed4c..cf083d9ec22 100644
--- a/mod/quiz/accessrule/seb/tests/rule_test.php
+++ b/mod/quiz/accessrule/seb/tests/rule_test.php
@@ -413,7 +413,7 @@ class rule_test extends \advanced_testcase {
         // Set quiz setting to require seb and save BEK.
         $quizsettings = seb_quiz_settings::get_record(['quizid' => $this->quiz->id]);
         $quizsettings->set('requiresafeexambrowser', settings_provider::USE_SEB_UPLOAD_CONFIG);
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
         $this->create_module_test_file($xml, $this->quiz->cmid);
         $quizsettings->save();
 
@@ -517,7 +517,7 @@ class rule_test extends \advanced_testcase {
         // Set quiz setting to require seb and save BEK.
         $quizsettings = seb_quiz_settings::get_record(['quizid' => $this->quiz->id]);
         $quizsettings->set('requiresafeexambrowser', settings_provider::USE_SEB_UPLOAD_CONFIG);
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
         $this->create_module_test_file($xml, $this->quiz->cmid);
         $quizsettings->save();
 
@@ -576,7 +576,7 @@ class rule_test extends \advanced_testcase {
         $quizsettings = seb_quiz_settings::get_record(['quizid' => $this->quiz->id]);
         $quizsettings->set('requiresafeexambrowser', settings_provider::USE_SEB_UPLOAD_CONFIG);
         $quizsettings->set('allowedbrowserexamkeys', $browserexamkey);
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
         $this->create_module_test_file($xml, $this->quiz->cmid);
         $quizsettings->save();
 
@@ -694,7 +694,7 @@ class rule_test extends \advanced_testcase {
         $quizsettings = seb_quiz_settings::get_record(['quizid' => $this->quiz->id]);
         $quizsettings->set('requiresafeexambrowser', settings_provider::USE_SEB_UPLOAD_CONFIG);
         $quizsettings->set('allowedbrowserexamkeys', $browserexamkey);
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
         $this->create_module_test_file($xml, $this->quiz->cmid);
         $quizsettings->save();
 
@@ -823,7 +823,7 @@ class rule_test extends \advanced_testcase {
         // Set quiz setting to require seb.
         $quizsettings = seb_quiz_settings::get_record(['quizid' => $this->quiz->id]);
         $quizsettings->set('requiresafeexambrowser', settings_provider::USE_SEB_UPLOAD_CONFIG); // Doesn't check basic header.
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
         $this->create_module_test_file($xml, $this->quiz->cmid);
         $quizsettings->save();
 
@@ -1082,7 +1082,7 @@ class rule_test extends \advanced_testcase {
 
         // Should see links when using uploaded config.
         $quizsettings->set('requiresafeexambrowser', settings_provider::USE_SEB_UPLOAD_CONFIG);
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
         $this->create_module_test_file($xml, $this->quiz->cmid);
         $quizsettings->save();
         $this->assertStringContainsString($this->get_seb_launch_link(), $method->invoke($this->make_rule()));
diff --git a/mod/quiz/accessrule/seb/tests/settings_provider_test.php b/mod/quiz/accessrule/seb/tests/settings_provider_test.php
index 821d1c9e36a..2fe2944370a 100644
--- a/mod/quiz/accessrule/seb/tests/settings_provider_test.php
+++ b/mod/quiz/accessrule/seb/tests/settings_provider_test.php
@@ -911,7 +911,7 @@ class settings_provider_test extends \advanced_testcase {
         $user = $this->getDataGenerator()->create_user();
         $this->setUser($user);
 
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
         $itemid = $this->create_test_draftarea_file($xml);
         $file = settings_provider::get_current_user_draft_file($itemid);
         $content = $file->get_content();
@@ -929,7 +929,7 @@ class settings_provider_test extends \advanced_testcase {
         $this->context = \context_module::instance($this->quiz->cmid);
         $this->set_up_user_and_role();
 
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
 
         $draftitemid = $this->create_test_draftarea_file($xml);
 
@@ -951,7 +951,7 @@ class settings_provider_test extends \advanced_testcase {
         $this->context = \context_module::instance($this->quiz->cmid);
         $this->set_up_user_and_role();
 
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
         $draftitemid = $this->create_test_draftarea_file($xml);
 
         settings_provider::save_filemanager_sebconfigfile_draftarea($draftitemid, $this->quiz->cmid);
@@ -980,7 +980,7 @@ class settings_provider_test extends \advanced_testcase {
 
         $this->set_up_user_and_role();
 
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
         $draftitemid = $this->create_test_draftarea_file($xml);
 
         $fs = get_file_storage();
@@ -1194,7 +1194,7 @@ class settings_provider_test extends \advanced_testcase {
         $this->context = \context_module::instance($this->quiz->cmid);
 
         // Save file.
-        $xml = file_get_contents(__DIR__ . '/fixtures/unencrypted.seb');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'unencrypted.seb'));
         $draftitemid = $this->create_test_draftarea_file($xml);
         settings_provider::save_filemanager_sebconfigfile_draftarea($draftitemid, $this->quiz->cmid);
         $settings = seb_quiz_settings::get_record(['quizid' => $this->quiz->id]);
diff --git a/mod/quiz/tests/restore_attempt_test.php b/mod/quiz/tests/restore_attempt_test.php
index 5fd21c18c9b..b44161a2c54 100644
--- a/mod/quiz/tests/restore_attempt_test.php
+++ b/mod/quiz/tests/restore_attempt_test.php
@@ -53,7 +53,7 @@ class restore_attempt_test extends \advanced_testcase {
         // Contains a quiz with four attempts from different users. The users are as follows (user ID -> user):
         // 3 -> User 01, 4 -> User 02, 5 -> User 03, 6 -> User 04.
         // The user details for User 02 and User 03 have been removed from the backup file.
-        $testfixture = __DIR__ . '/fixtures/question_attempts_missing_users.mbz';
+        $testfixture = self::get_fixture_path(__NAMESPACE__, 'question_attempts_missing_users.mbz');
 
         // Extract our test fixture, ready to be restored.
         $backuptempdir = 'aaa';
diff --git a/privacy/tests/moodle_content_writer_test.php b/privacy/tests/moodle_content_writer_test.php
index d718f70ca6c..7b05e466e60 100644
--- a/privacy/tests/moodle_content_writer_test.php
+++ b/privacy/tests/moodle_content_writer_test.php
@@ -507,7 +507,7 @@ class moodle_content_writer_test extends advanced_testcase {
                 0,
                 '/',
                 'logo.png',
-                file_get_contents(__DIR__ . '/fixtures/logo.png'),
+                file_get_contents(self::get_fixture_path('core_privacy', 'logo.png')),
             ],
             'UTF8' => [
                 'submission_content',
diff --git a/privacy/tests/request_helper_test.php b/privacy/tests/request_helper_test.php
index 06241f4b813..045312940e1 100644
--- a/privacy/tests/request_helper_test.php
+++ b/privacy/tests/request_helper_test.php
@@ -203,7 +203,7 @@ class request_helper_test extends advanced_testcase {
             'filename'  => 'logo.png',
         );
 
-        $content = file_get_contents(__DIR__ . '/fixtures/logo.png');
+        $content = file_get_contents(self::get_fixture_path('core_privacy', 'logo.png'));
 
         // Store the file.
         $fs = get_file_storage();
diff --git a/question/format/blackboard_six/tests/blackboardformatpool_test.php b/question/format/blackboard_six/tests/blackboardformatpool_test.php
index bc905a2bf66..f11184c250b 100644
--- a/question/format/blackboard_six/tests/blackboardformatpool_test.php
+++ b/question/format/blackboard_six/tests/blackboardformatpool_test.php
@@ -41,7 +41,7 @@ class blackboardformatpool_test extends \question_testcase {
     public function make_test_xml() {
         $xmlfile = new qformat_blackboard_six_file();
         $xmlfile->filetype = 2;
-        $xmlfile->text = file_get_contents(__DIR__ . '/fixtures/sample_blackboard_pool.dat');
+        $xmlfile->text = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'sample_blackboard_pool.dat'));
         return array(0 => $xmlfile);
     }
 
diff --git a/question/format/blackboard_six/tests/blackboardsixformatqti_test.php b/question/format/blackboard_six/tests/blackboardsixformatqti_test.php
index 3482c722850..5e92e8929e3 100644
--- a/question/format/blackboard_six/tests/blackboardsixformatqti_test.php
+++ b/question/format/blackboard_six/tests/blackboardsixformatqti_test.php
@@ -41,7 +41,7 @@ class blackboardsixformatqti_test extends \question_testcase {
     public function make_test_xml() {
         $xmlfile = new qformat_blackboard_six_file();
         $xmlfile->filetype = 1;
-        $xmlfile->text = file_get_contents(__DIR__ . '/fixtures/sample_blackboard_qti.dat');
+        $xmlfile->text = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'sample_blackboard_qti.dat'));
         return array(0 => $xmlfile);
     }
     public function test_import_match(): void {
diff --git a/question/format/multianswer/tests/multianswerformat_test.php b/question/format/multianswer/tests/multianswerformat_test.php
index 6f9db955d0d..ad86c976309 100644
--- a/question/format/multianswer/tests/multianswerformat_test.php
+++ b/question/format/multianswer/tests/multianswerformat_test.php
@@ -37,7 +37,7 @@ require_once($CFG->dirroot . '/question/engine/tests/helpers.php');
 class multianswerformat_test extends \question_testcase {
 
     public function test_import(): void {
-        $lines = file(__DIR__ . '/fixtures/questions.multianswer.txt');
+        $lines = file(self::get_fixture_path(__NAMESPACE__, 'questions.multianswer.txt'));
 
         $importer = new qformat_multianswer();
         $qs = $importer->readquestions($lines);
@@ -73,7 +73,7 @@ The capital of France is {#5}.
     }
 
     public function test_read_brokencloze_1(): void {
-        $lines = file(__DIR__ . '/fixtures/broken_multianswer_1.txt');
+        $lines = file(self::get_fixture_path(__NAMESPACE__, 'broken_multianswer_1.txt'));
         $importer = new qformat_multianswer();
 
         // The importer echoes some errors, so we need to capture and check that.
@@ -92,7 +92,7 @@ The capital of France is {#5}.
     }
 
     public function test_read_brokencloze_2(): void {
-        $lines = file(__DIR__ . '/fixtures/broken_multianswer_2.txt');
+        $lines = file(self::get_fixture_path(__NAMESPACE__, 'broken_multianswer_2.txt'));
         $importer = new qformat_multianswer();
 
         // The importer echoes some errors, so we need to capture and check that.
@@ -112,7 +112,7 @@ The capital of France is {#5}.
     }
 
     public function test_read_brokencloze_3(): void {
-        $lines = file(__DIR__ . '/fixtures/broken_multianswer_3.txt');
+        $lines = file(self::get_fixture_path(__NAMESPACE__, 'broken_multianswer_3.txt'));
         $importer = new qformat_multianswer();
 
         // The importer echoes some errors, so we need to capture and check that.
@@ -131,7 +131,7 @@ The capital of France is {#5}.
     }
 
     public function test_read_brokencloze_4(): void {
-        $lines = file(__DIR__ . '/fixtures/broken_multianswer_4.txt');
+        $lines = file(self::get_fixture_path(__NAMESPACE__, 'broken_multianswer_4.txt'));
         $importer = new qformat_multianswer();
 
         // The importer echoes some errors, so we need to capture and check that.
diff --git a/question/format/xml/tests/qformat_xml_import_export_test.php b/question/format/xml/tests/qformat_xml_import_export_test.php
index 37be1dceb16..5b5bdea9a5a 100644
--- a/question/format/xml/tests/qformat_xml_import_export_test.php
+++ b/question/format/xml/tests/qformat_xml_import_export_test.php
@@ -295,7 +295,7 @@ class qformat_xml_import_export_test extends advanced_testcase {
                 'penalty' => '1']);
         $qformat->setCategory($category);
 
-        $expectedxml = file_get_contents(__DIR__ . '/fixtures/export_category.xml');
+        $expectedxml = file_get_contents(self::get_fixture_path('qformat_xml', 'export_category.xml'));
         $this->assert_same_xml($expectedxml, $qformat->exportprocess());
     }
 
@@ -459,7 +459,7 @@ class qformat_xml_import_export_test extends advanced_testcase {
                 'penalty' => '1']);
         $qformat->setCategory($categoryiota);
 
-        $expectedxml = file_get_contents(__DIR__ . '/fixtures/nested_categories_with_questions.xml');
+        $expectedxml = file_get_contents(self::get_fixture_path('qformat_xml', 'nested_categories_with_questions.xml'));
         $this->assert_same_xml($expectedxml, $qformat->exportprocess());
     }
 
@@ -498,7 +498,7 @@ class qformat_xml_import_export_test extends advanced_testcase {
                 'penalty' => '1']);
         $qformat->setCategory($category);
 
-        $expectedxml = file_get_contents(__DIR__ . '/fixtures/html_chars_in_idnumbers.xml');
+        $expectedxml = file_get_contents(self::get_fixture_path('qformat_xml', 'html_chars_in_idnumbers.xml'));
         $this->assert_same_xml($expectedxml, $qformat->exportprocess());
     }
 
@@ -506,7 +506,7 @@ class qformat_xml_import_export_test extends advanced_testcase {
      * Test that bad multianswer questions are not imported.
      */
     public function test_import_broken_multianswer_questions(): void {
-        $lines = file(__DIR__ . '/fixtures/broken_cloze_questions.xml');
+        $lines = file(self::get_fixture_path('qformat_xml', 'broken_cloze_questions.xml'));
         $importer = $qformat = new qformat_xml();
 
         // The importer echoes some errors, so we need to capture and check that.
diff --git a/question/type/ordering/tests/questiontype_test.php b/question/type/ordering/tests/questiontype_test.php
index 5a390258ba4..f376717c832 100644
--- a/question/type/ordering/tests/questiontype_test.php
+++ b/question/type/ordering/tests/questiontype_test.php
@@ -237,7 +237,7 @@ final class questiontype_test extends \question_testcase {
     public function test_xml_import(): void {
         $this->resetAfterTest();
         // Import a question from XML.
-        $xml = file_get_contents(__DIR__ . '/fixtures/testimport.moodle.xml');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'testimport.moodle.xml'));
         $xmldata = xmlize($xml);
         $format = new qformat_xml();
         $imported = $format->try_importing_using_qtypes(
@@ -249,7 +249,7 @@ final class questiontype_test extends \question_testcase {
     public function test_xml_import_long(): void {
         $this->resetAfterTest();
         // Import a question from XML.
-        $xml = file_get_contents(__DIR__ . '/fixtures/testimportlong.moodle.xml');
+        $xml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'testimportlong.moodle.xml'));
         $xmldata = xmlize($xml);
         $format = new qformat_xml();
         $imported = $format->try_importing_using_qtypes(
@@ -283,7 +283,7 @@ final class questiontype_test extends \question_testcase {
         $exporter = new qformat_xml();
         $xml = $exporter->writequestion($questiondata);
 
-        $expectedxml = file_get_contents(__DIR__ . '/fixtures/testexport.moodle.xml');
+        $expectedxml = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'testexport.moodle.xml'));
 
         $this->assert_same_xml($expectedxml, $xml);
     }
@@ -291,7 +291,7 @@ final class questiontype_test extends \question_testcase {
     public function test_gift_import(): void {
         $this->resetAfterTest();
         // Import a question from GIFT.
-        $gift = file_get_contents(__DIR__ . '/fixtures/testimport.gift.txt');
+        $gift = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'testimport.gift.txt'));
         $format = new qformat_gift();
         $lines = preg_split('/[\\n\\r]/', phpunit_util::normalise_line_endings($gift));
         $imported = $format->readquestion($lines);
@@ -314,7 +314,7 @@ final class questiontype_test extends \question_testcase {
         $exporter = new qformat_gift();
         $gift = $exporter->writequestion($questiondata);
 
-        $expectedgift = file_get_contents(__DIR__ . '/fixtures/testexport.gift.txt');
+        $expectedgift = file_get_contents(self::get_fixture_path(__NAMESPACE__, 'testexport.gift.txt'));
 
         $this->assertEquals(
             phpunit_util::normalise_line_endings($expectedgift),