Make Localization.relativeTime testable

Problem is global state in static variable prettyTime. But for performance reasons on Android that is preferred.
Now allow injecting prettyTime dependency by making init function public.

app/src/main/java/org/schabi/newpipe/App.java

@@ -6,16 +6,26 @@ import android.content.Context;
 import android.content.SharedPreferences;
 import android.os.Build;
 import android.util.Log;
-
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.multidex.MultiDexApplication;
 import androidx.preference.PreferenceManager;
-
 import com.nostra13.universalimageloader.cache.memory.impl.LRULimitedMemoryCache;
 import com.nostra13.universalimageloader.core.ImageLoader;
 import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;
-
+import io.reactivex.rxjava3.disposables.Disposable;
+import io.reactivex.rxjava3.exceptions.CompositeException;
+import io.reactivex.rxjava3.exceptions.MissingBackpressureException;
+import io.reactivex.rxjava3.exceptions.OnErrorNotImplementedException;
+import io.reactivex.rxjava3.exceptions.UndeliverableException;
+import io.reactivex.rxjava3.functions.Consumer;
+import io.reactivex.rxjava3.plugins.RxJavaPlugins;
+import java.io.IOException;
+import java.io.InterruptedIOException;
+import java.net.SocketException;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
 import org.acra.ACRA;
 import org.acra.config.ACRAConfigurationException;
 import org.acra.config.CoreConfiguration;
@@ -31,21 +41,6 @@ import org.schabi.newpipe.util.Localization;
 import org.schabi.newpipe.util.ServiceHelper;
 import org.schabi.newpipe.util.StateSaver;
 
-import java.io.IOException;
-import java.io.InterruptedIOException;
-import java.net.SocketException;
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.List;
-
-import io.reactivex.rxjava3.disposables.Disposable;
-import io.reactivex.rxjava3.exceptions.CompositeException;
-import io.reactivex.rxjava3.exceptions.MissingBackpressureException;
-import io.reactivex.rxjava3.exceptions.OnErrorNotImplementedException;
-import io.reactivex.rxjava3.exceptions.UndeliverableException;
-import io.reactivex.rxjava3.functions.Consumer;
-import io.reactivex.rxjava3.plugins.RxJavaPlugins;
-
 /*
  * Copyright (C) Hans-Christoph Steiner 2016 <hans@eds.org>
  * App.java is part of NewPipe.
@@ -93,9 +88,9 @@ public class App extends MultiDexApplication {
         SettingsActivity.initSettings(this);
 
         NewPipe.init(getDownloader(),
-                Localization.getPreferredLocalization(this),
+            Localization.getPreferredLocalization(this),
-                Localization.getPreferredContentCountry(this));
+            Localization.getPreferredContentCountry(this));
-        Localization.init(getApplicationContext());
+        Localization.initPrettyTime(Localization.resolvePrettyTime(getApplicationContext()));
 
         StateSaver.init(this);
         initNotificationChannels();

app/src/main/java/org/schabi/newpipe/MainActivity.java

@@ -20,6 +20,8 @@
 
 package org.schabi.newpipe;
 
+import static org.schabi.newpipe.util.Localization.assureCorrectAppLanguage;
+
 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
@@ -41,7 +43,6 @@ import android.widget.AdapterView;
 import android.widget.ArrayAdapter;
 import android.widget.FrameLayout;
 import android.widget.Spinner;
-
 import androidx.annotation.NonNull;
 import androidx.appcompat.app.ActionBar;
 import androidx.appcompat.app.ActionBarDrawerToggle;
@@ -52,9 +53,10 @@ import androidx.drawerlayout.widget.DrawerLayout;
 import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentManager;
 import androidx.preference.PreferenceManager;
-
 import com.google.android.material.bottomsheet.BottomSheetBehavior;
-
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
 import org.schabi.newpipe.databinding.ActivityMainBinding;
 import org.schabi.newpipe.databinding.DrawerHeaderBinding;
 import org.schabi.newpipe.databinding.DrawerLayoutBinding;
@@ -87,12 +89,6 @@ import org.schabi.newpipe.util.TLSSocketFactoryCompat;
 import org.schabi.newpipe.util.ThemeHelper;
 import org.schabi.newpipe.views.FocusOverlayView;
 
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Objects;
-
-import static org.schabi.newpipe.util.Localization.assureCorrectAppLanguage;
-
 public class MainActivity extends AppCompatActivity {
     private static final String TAG = "MainActivity";
     public static final boolean DEBUG = !BuildConfig.BUILD_TYPE.equals("release");
@@ -468,7 +464,7 @@ public class MainActivity extends AppCompatActivity {
     protected void onResume() {
         assureCorrectAppLanguage(this);
         // Change the date format to match the selected language on resume
-        Localization.init(getApplicationContext());
+        Localization.initPrettyTime(Localization.resolvePrettyTime(getApplicationContext()));
         super.onResume();
 
         // Close drawer on return, and don't show animation,

app/src/main/java/org/schabi/newpipe/util/Localization.java

@@ -9,19 +9,10 @@ import android.icu.text.CompactDecimalFormat;
 import android.os.Build;
 import android.text.TextUtils;
 import android.util.DisplayMetrics;
-
 import androidx.annotation.NonNull;
 import androidx.annotation.PluralsRes;
 import androidx.annotation.StringRes;
 import androidx.preference.PreferenceManager;
-
-import org.ocpsoft.prettytime.PrettyTime;
-import org.ocpsoft.prettytime.units.Decade;
-import org.schabi.newpipe.R;
-import org.schabi.newpipe.extractor.ListExtractor;
-import org.schabi.newpipe.extractor.localization.ContentCountry;
-import org.schabi.newpipe.ktx.OffsetDateTimeKt;
-
 import java.math.BigDecimal;
 import java.math.RoundingMode;
 import java.text.NumberFormat;
@@ -33,6 +24,12 @@ import java.util.Arrays;
 import java.util.Calendar;
 import java.util.List;
 import java.util.Locale;
+import org.ocpsoft.prettytime.PrettyTime;
+import org.ocpsoft.prettytime.units.Decade;
+import org.schabi.newpipe.R;
+import org.schabi.newpipe.extractor.ListExtractor;
+import org.schabi.newpipe.extractor.localization.ContentCountry;
+import org.schabi.newpipe.ktx.OffsetDateTimeKt;
 
 
 /*
@@ -62,10 +59,6 @@ public final class Localization {
 
     private Localization() { }
 
-    public static void init(final Context context) {
-        initPrettyTime(context);
-    }
-
     @NonNull
     public static String concatenateStrings(final String... strings) {
         return concatenateStrings(Arrays.asList(strings));
@@ -307,12 +300,16 @@ public final class Localization {
     // Pretty Time
     //////////////////////////////////////////////////////////////////////////*/
 
-    private static void initPrettyTime(final Context context) {
+    public static void initPrettyTime(final PrettyTime time) {
-        prettyTime = new PrettyTime(getAppLocale(context));
+        prettyTime = time;
         // Do not use decades as YouTube doesn't either.
         prettyTime.removeUnit(Decade.class);
     }
 
+    public static PrettyTime resolvePrettyTime(final Context context) {
+        return new PrettyTime(getAppLocale(context));
+    }
+
     public static String relativeTime(final OffsetDateTime offsetDateTime) {
         return relativeTime(OffsetDateTimeKt.toCalendar(offsetDateTime));
     }

app/src/test/java/org/schabi/newpipe/util/LocalizationTest.kt

@@ -0,0 +1,39 @@
+package org.schabi.newpipe.util
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import org.ocpsoft.prettytime.PrettyTime
+import java.text.SimpleDateFormat
+import java.time.OffsetDateTime
+import java.time.ZoneOffset
+import java.util.GregorianCalendar
+import java.util.Locale
+
+class LocalizationTest {
+
+    @Test
+    fun `After initializing pretty time relativeTime() with a Calendar must work`() {
+        val reference = SimpleDateFormat("yyyy/MM/dd").parse("2021/1/1")
+        Localization.initPrettyTime(PrettyTime(reference, Locale.ENGLISH))
+
+        val actual = Localization.relativeTime(GregorianCalendar(2021, 1, 6))
+
+        assertEquals("1 month from now", actual)
+    }
+
+    @Test(expected = NullPointerException::class)
+    fun `relativeTime() must fail without initializing pretty time`() {
+        Localization.relativeTime(GregorianCalendar(2021, 1, 6))
+    }
+
+    @Test
+    fun `relativeTime() with a OffsetDateTime must work`() {
+        val reference = SimpleDateFormat("yyyy/MM/dd").parse("2021/1/1")
+        Localization.initPrettyTime(PrettyTime(reference, Locale.ENGLISH))
+
+        val offset = OffsetDateTime.of(2021, 1, 6, 0, 0, 0, 0, ZoneOffset.UTC)
+        val actual = Localization.relativeTime(offset)
+
+        assertEquals("5 days from now", actual)
+    }
+}