MOBILE-4901 lang: Add behat testing for custom lang strings

Author: crazyserver

src/core/tests/behat/customlangstrings.feature

@@ -20,3 +20,26 @@ Feature: Test language changes
 
     When I change language to "es" in the app
     Then I should find "Mis cursos" in the app
+
+  Scenario: Custom lang strings
+    Given I log in as "admin"
+    And I navigate to "General > Mobile app > Mobile features" in site administration
+    And I set the field "Custom language strings" to multiline:
+    """
+    core.courses.mycourses|Foo|en
+    core.courses.mycourses| Foo amb espais |ca
+    core.course.nocontentavailable| No content here |en_us
+    addon.block_timeline.pluginnames|Linetime|en
+    """
+    And I press "Save changes"
+
+    When I entered the app as "student1"
+    Then I should be able to press "Foo" in the app
+    Then I should not find "No content here" in the app
+
+    When I change language to "ca" in the app
+    Then I should be able to press "Foo amb espais" in the app
+
+    When I change language to "en_us" in the app
+    Then I should be able to press "Foo" in the app
+    Then I should find "No content here" in the app