[android] add fallback support to local ideograph font families, allow setting a collection of fonts

platform/android/MapboxGLAndroidSDKTestApp/src/androidTest/java/com/mapbox/mapboxsdk/utils/FontUtilsTest.java

@@ -0,0 +1,43 @@
+package com.mapbox.mapboxsdk.utils;
+
+import android.support.test.runner.AndroidJUnit4;
+
+import com.mapbox.mapboxsdk.constants.MapboxConstants;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+@RunWith(AndroidJUnit4.class)
+public class FontUtilsTest {
+
+  @Test
+  public void testExtractedFontShouldMatchDefault() {
+    String[] fonts = new String[] {"foo", "bar"};
+    String actual = FontUtils.extractValidFont(fonts);
+    assertEquals("Selected font should match", MapboxConstants.DEFAULT_FONT, actual);
+  }
+
+  @Test
+  public void testExtractedFontShouldMatchMonospace() {
+    String expected = "monospace";
+    String[] fonts = new String[] {"foo", expected};
+    String actual = FontUtils.extractValidFont(fonts);
+    assertEquals("Selected font should match", expected, actual);
+  }
+
+  @Test
+  public void testExtractedFontArrayShouldBeNull() {
+    String[] fonts = null;
+    String actual = FontUtils.extractValidFont(fonts);
+    assertNull(actual);
+  }
+
+  @Test
+  public void testExtractedFontShouldBeNull() {
+    String actual = FontUtils.extractValidFont(null);
+    assertNull(actual);
+  }
+}