[android] - fix accesstoken validation

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/Mapbox.java

@@ -7,7 +7,6 @@ import android.net.NetworkInfo;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.annotation.UiThread;
-import android.text.TextUtils;
 import com.mapbox.mapboxsdk.constants.MapboxConstants;
 import com.mapbox.mapboxsdk.exceptions.MapboxConfigurationException;
 import com.mapbox.mapboxsdk.maps.Telemetry;
@@ -138,8 +137,12 @@ public final class Mapbox {
    * @param accessToken the access token to validate
    * @return true is valid, false otherwise
    */
-  private static boolean isAccessTokenValid(String accessToken) {
-    return !(TextUtils.isEmpty(accessToken)
-      || (!accessToken.toLowerCase(MapboxConstants.MAPBOX_LOCALE).startsWith("pk.")));
+  static boolean isAccessTokenValid(String accessToken) {
+    if (accessToken == null) {
+      return false;
+    }
+
+    accessToken = accessToken.trim().toLowerCase(MapboxConstants.MAPBOX_LOCALE);
+    return accessToken.length() != 0 && (accessToken.startsWith("pk.") || accessToken.startsWith("sk."));
   }
 }

platform/android/MapboxGLAndroidSDK/src/test/java/com/mapbox/mapboxsdk/MapboxTest.java

@@ -3,7 +3,6 @@ package com.mapbox.mapboxsdk;
 import android.content.Context;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
-
 import org.junit.Before;
 import org.junit.Test;
 
@@ -45,6 +44,31 @@ public class MapboxTest {
     assertEquals(appContext, appContext);
   }
 
+  @Test
+  public void testPkTokenValid() {
+    assertTrue(Mapbox.isAccessTokenValid("pk.0000000001"));
+  }
+
+  @Test
+  public void testSkTokenValid() {
+    assertTrue(Mapbox.isAccessTokenValid("sk.0000000001"));
+  }
+
+  @Test
+  public void testEmptyToken() {
+    assertFalse(Mapbox.isAccessTokenValid(""));
+  }
+
+  @Test
+  public void testNullToken() {
+    assertFalse(Mapbox.isAccessTokenValid(null));
+  }
+
+  @Test
+  public void testBlaBlaToken() {
+    assertFalse(Mapbox.isAccessTokenValid("blabla"));
+  }
+
   @Test
   public void testConnected() {
     injectMapboxSingleton("dummy");