diff --git a/test/unit/php/includes/core/classes/class-test-event-setup.php b/test/unit/php/includes/core/classes/class-test-event-setup.php
index a54e7aed5..eb4eb3974 100644
--- a/test/unit/php/includes/core/classes/class-test-event-setup.php
+++ b/test/unit/php/includes/core/classes/class-test-event-setup.php
@@ -125,9 +125,32 @@ public function test_get_localized_post_type_slug(): void {
 		$this->assertSame(
 			'event',
 			Event_Setup::get_localized_post_type_slug(),
-			'Failed to assert english post type slug is "event".'
+			'Failed to assert English post type slug is "event".'
 		);
 
+		$user_id  = $this->factory->user->create();
+		update_user_meta( $user_id, 'locale', 'es_ES' );
+		switch_to_user_locale( $user_id );
+
+		// @todo This assertion CAN NOT FAIL,
+		//       until real translations do exist in the wp-env instance.
+		//       Because WordPress doesn't have any translation files to load,
+		//       it will return the string in English.
+		$this->assertSame(
+			'event',
+			Event_Setup::get_localized_post_type_slug(),
+			'Failed to assert post type slug is "event", even the locale is not English anymore.'
+		);
+		// But at least the restoring of the user locale can be tested, without .po files.
+		$this->assertSame(
+			'es_ES',
+			determine_locale(),
+			'Failed to assert locale was reset to Spanish, after switching to ~ and restoring from English.'
+		);
+
+		// Restore default locale for following tests.
+		switch_to_locale( 'en_US' );
+
 		// This also checks that the post type is still registered with the same 'Post Type Singular Name' label,
 		// which is used by the method under test and the test itself.
 		$filter = static function ( string $translation, string $text, string $context ): string {
diff --git a/test/unit/php/includes/core/classes/class-test-topic.php b/test/unit/php/includes/core/classes/class-test-topic.php
index b5e6b0fd1..cc16b2097 100644
--- a/test/unit/php/includes/core/classes/class-test-topic.php
+++ b/test/unit/php/includes/core/classes/class-test-topic.php
@@ -70,9 +70,32 @@ public function test_get_localized_taxonomy_slug(): void {
 		$this->assertSame(
 			'topic',
 			Topic::get_localized_taxonomy_slug(),
-			'Failed to assert english taxonomy slug is "topic".'
+			'Failed to assert English taxonomy slug is "topic".'
 		);
 
+		$user_id  = $this->factory->user->create();
+		update_user_meta( $user_id, 'locale', 'es_ES' );
+		switch_to_user_locale( $user_id );
+
+		// @todo This assertion CAN NOT FAIL,
+		//       until real translations do exist in the wp-env instance.
+		//       Because WordPress doesn't have any translation files to load,
+		//       it will return the string in English.
+		$this->assertSame(
+			'topic',
+			Topic::get_localized_taxonomy_slug(),
+			'Failed to assert taxonomy slug is "topic", even the locale is not English anymore.'
+		);
+		// But at least the restoring of the user locale can be tested, without .po files.
+		$this->assertSame(
+			'es_ES',
+			determine_locale(),
+			'Failed to assert locale was reset to Spanish, after switching to ~ and restoring from English.'
+		);
+
+		// Restore default locale for following tests.
+		switch_to_locale( 'en_US' );
+
 		// This also checks that the taxonomy is still registered with the same 'Taxonomy Singular Name' label,
 		// which is used by the method under test and the test itself.
 		$filter = static function ( string $translation, string $text, string $context ): string {
diff --git a/test/unit/php/includes/core/classes/class-test-venue.php b/test/unit/php/includes/core/classes/class-test-venue.php
index 39590efa4..a3332175f 100644
--- a/test/unit/php/includes/core/classes/class-test-venue.php
+++ b/test/unit/php/includes/core/classes/class-test-venue.php
@@ -100,9 +100,32 @@ public function test_get_localized_post_type_slug(): void {
 		$this->assertSame(
 			'venue',
 			Venue::get_localized_post_type_slug(),
-			'Failed to assert english post type slug is "venue".'
+			'Failed to assert English post type slug is "venue".'
 		);
 
+		$user_id  = $this->factory->user->create();
+		update_user_meta( $user_id, 'locale', 'es_ES' );
+		switch_to_user_locale( $user_id );
+
+		// @todo This assertion CAN NOT FAIL,
+		//       until real translations do exist in the wp-env instance.
+		//       Because WordPress doesn't have any translation files to load,
+		//       it will return the string in English.
+		$this->assertSame(
+			'venue',
+			Venue::get_localized_post_type_slug(),
+			'Failed to assert post type slug is "venue", even the locale is not English anymore.'
+		);
+		// But at least the restoring of the user locale can be tested, without .po files.
+		$this->assertSame(
+			'es_ES',
+			determine_locale(),
+			'Failed to assert locale was reset to Spanish, after switching to ~ and restoring from English.'
+		);
+
+		// Restore default locale for following tests.
+		switch_to_locale( 'en_US' );
+
 		// This also checks that the post type is still registered with the same 'Post Type Singular Name' label,
 		// which is used by the method under test and the test itself.
 		$filter = static function ( string $translation, string $text, string $context ): string {