test: add DefaultHomeLocalDataSource tests

app/src/test/java/com/d4rk/androidtutorials/java/data/source/DefaultHomeLocalDataSourceTest.java

@@ -0,0 +1,43 @@
+package com.d4rk.androidtutorials.java.data.source;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import android.content.Context;
+import android.content.res.Resources;
+
+import com.d4rk.androidtutorials.java.R;
+
+import org.junit.Test;
+
+public class DefaultHomeLocalDataSourceTest {
+
+    @Test
+    public void playStoreUrlsFormattedCorrectly() {
+        DefaultHomeLocalDataSource dataSource =
+                new DefaultHomeLocalDataSource(mockContextWithTips(new String[]{"tip"}));
+        assertEquals("https://play.google.com/store/apps/details?id=com.d4rk.androidtutorials", dataSource.getPlayStoreUrl());
+        assertEquals("https://play.google.com/store/apps/details?id=pkg", dataSource.getAppPlayStoreUrl("pkg"));
+    }
+
+    @Test
+    public void dailyTipUsesEpochDayIndex() {
+        String[] tips = {"tip1", "tip2", "tip3"};
+        Context context = mockContextWithTips(tips);
+        DefaultHomeLocalDataSource dataSource = new DefaultHomeLocalDataSource(context);
+
+        long daysSinceEpoch = System.currentTimeMillis() / (24L * 60L * 60L * 1000L);
+        int expectedIndex = (int) (daysSinceEpoch % tips.length);
+        assertEquals(tips[expectedIndex], dataSource.getDailyTip());
+    }
+
+    private static Context mockContextWithTips(String[] tips) {
+        Context context = mock(Context.class);
+        Resources resources = mock(Resources.class);
+        when(context.getApplicationContext()).thenReturn(context);
+        when(context.getResources()).thenReturn(resources);
+        when(resources.getStringArray(R.array.daily_tips)).thenReturn(tips);
+        return context;
+    }
+}