Add test to ensure legacy storage access

brouter-routing-app/build.gradle

@@ -17,6 +17,8 @@ android {
         setProperty("archivesBaseName","BRouterApp." + defaultConfig.versionName)
 
         minSdkVersion 14
+        
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 
     sourceSets.main.assets.srcDirs += new File(project.buildDir, 'assets')
@@ -99,6 +101,10 @@ dependencies {
     implementation project(':brouter-expressions')
     implementation project(':brouter-util')
 
+    testImplementation 'junit:junit:4.13.2'
+
+    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
 }
 
 task generateProfiles(type: Exec) {

brouter-routing-app/src/androidTest/java/btools/routingapp/BRouterActivityTest.java

@@ -0,0 +1,47 @@
+package btools.routingapp;
+
+import static org.hamcrest.Matchers.empty;
+import static org.hamcrest.Matchers.hasItem;
+import static org.hamcrest.Matchers.not;
+import static org.junit.Assert.assertThat;
+
+import android.os.Build;
+import android.os.Environment;
+
+import androidx.test.core.app.ActivityScenario;
+import androidx.test.ext.junit.rules.ActivityScenarioRule;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.io.File;
+import java.util.List;
+
+@RunWith(AndroidJUnit4.class)
+public class BRouterActivityTest {
+  @Rule
+  public ActivityScenarioRule<BRouterActivity> rule = new ActivityScenarioRule<>(BRouterActivity.class);
+
+  @Test
+  public void storageDirectories() {
+    ActivityScenario<BRouterActivity> scenario = rule.getScenario();
+    scenario.onActivity(activity -> {
+      List<File> storageDirectories = activity.getStorageDirectories();
+
+      // Before Android Q (10) legacy storage access is possible
+      if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q) {
+        assertThat(storageDirectories, hasItem(Environment.getExternalStorageDirectory()));
+      }
+
+      // When targeting older SDK we can access legacy storage on any android version
+      if (activity.getApplicationInfo().targetSdkVersion < Build.VERSION_CODES.Q) {
+        assertThat(storageDirectories, hasItem(Environment.getExternalStorageDirectory()));
+      }
+
+      assertThat(storageDirectories, not(empty()));
+    });
+  }
+
+}