EspressoCategoryUnitTest needs to set metricUnits.

src/androidTest/java/de/dennisguse/opentracks/EspressoCategoryUnitTest.java

@@ -1,6 +1,7 @@
 package de.dennisguse.opentracks;
 
 
+import android.content.Context;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.ViewParent;
@@ -12,6 +13,7 @@ import androidx.test.espresso.ViewInteraction;
 import androidx.test.ext.junit.rules.ActivityScenarioRule;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import androidx.test.filters.LargeTest;
+import androidx.test.platform.app.InstrumentationRegistry;
 import androidx.test.rule.GrantPermissionRule;
 
 import org.hamcrest.Description;
@@ -19,6 +21,7 @@ import org.hamcrest.Matcher;
 import org.hamcrest.TypeSafeMatcher;
 import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.TestRule;
 import org.junit.runner.RunWith;
 
 import static androidx.test.espresso.Espresso.onData;
@@ -47,7 +50,12 @@ public class EspressoCategoryUnitTest {
     public ActivityScenarioRule<TrackListActivity> mActivityTestRule = new ActivityScenarioRule<>(TrackListActivity.class);
 
     @Rule
-    public GrantPermissionRule mRuntimePermissionRule = GrantPermissionRule.grant(android.Manifest.permission.ACCESS_FINE_LOCATION);
+    public TestRule mRuntimePermissionRule = GrantPermissionRule.grant(android.Manifest.permission.ACCESS_FINE_LOCATION);
+
+    private final Context context = InstrumentationRegistry.getInstrumentation().getTargetContext();
+
+    @Rule
+    public TestRule mLocaleRule = new PreferenceMetricUnitRule(context, true);
 
     @Test
     public void changeBetweenCategoryUpdateProperlyUnitTest() {

src/androidTest/java/de/dennisguse/opentracks/PreferenceMetricUnitRule.java

@@ -0,0 +1,40 @@
+package de.dennisguse.opentracks;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+
+import androidx.annotation.NonNull;
+
+import org.junit.rules.TestRule;
+import org.junit.runner.Description;
+import org.junit.runners.model.Statement;
+
+import de.dennisguse.opentracks.util.PreferencesUtils;
+
+public class PreferenceMetricUnitRule implements TestRule {
+    private final Context context;
+    private final boolean metricUnits;
+
+    public PreferenceMetricUnitRule(@NonNull Context context, boolean metricUnits) {
+        this.context = context;
+        this.metricUnits = metricUnits;
+    }
+
+    @Override
+    public Statement apply(final Statement base, final Description description) {
+        return new Statement() {
+            @Override
+            public void evaluate() throws Throwable {
+                SharedPreferences sharedPreferences = PreferencesUtils.getSharedPreferences(context);
+                final boolean previousMetricUnits = PreferencesUtils.isMetricUnits(sharedPreferences, context);
+
+                try {
+                    PreferencesUtils.setMetricUnits(sharedPreferences, context, metricUnits);
+                    base.evaluate();
+                } finally {
+                    PreferencesUtils.setMetricUnits(sharedPreferences, context, previousMetricUnits);
+                }
+            }
+        };
+    }
+}

src/main/java/de/dennisguse/opentracks/Startup.java

@@ -30,8 +30,7 @@ public class Startup extends Application {
         // Set default values of preferences on first start.
         SharedPreferences sharedPreferences = PreferencesUtils.resetPreferences(this, false);
         if (PreferencesUtils.getString(sharedPreferences, this, R.string.stats_units_key, "").equals("")) {
-            String statsUnits = getString(Locale.US.equals(Locale.getDefault()) ? R.string.stats_units_imperial : R.string.stats_units_metric);
-            PreferencesUtils.setString(sharedPreferences, this, R.string.stats_units_key, statsUnits);
+            PreferencesUtils.setMetricUnits(sharedPreferences, this, !Locale.US.equals(Locale.getDefault()));
         }
 
         ActivityUtils.applyNightMode(sharedPreferences, this);

src/main/java/de/dennisguse/opentracks/util/PreferencesUtils.java

@@ -112,6 +112,16 @@ public class PreferencesUtils {
         return STATS_UNIT.equals(getString(sharedPreferences, context, R.string.stats_units_key, STATS_UNIT));
     }
 
+    public static void setMetricUnits(SharedPreferences sharedPreferences, Context context, boolean metricUnits) {
+        String unit;
+        if (metricUnits) {
+            unit = context.getString(R.string.stats_units_metric);
+        } else {
+            unit = context.getString(R.string.stats_units_imperial);
+        }
+        setString(sharedPreferences, context, R.string.stats_units_key, unit);
+    }
+
     public static boolean isReportSpeed(SharedPreferences sharedPreferences, Context context, String category) {
         final String STATS_RATE_DEFAULT = context.getString(R.string.stats_rate_default);
         String currentStatsRate = getString(sharedPreferences, context, R.string.stats_rate_key, STATS_RATE_DEFAULT);