Android unit testing and best practices

I am new to Android and I have a utility class (something like the following):

  public static TextView constructTextView(Context context, int id,
                                             String text, int size, int color, String font) {
        TextView textView = new TextView(context);
        if (id > 0) {
            textView.setId(id);
        }
        textView.setText(text);
        textView.setTextSize(TypedValue.COMPLEX_UNIT_SP, size);
        Typeface typeface = Typeface.createFromAsset(context.getAssets(),
                "fonts/" + font);
        textView.setTypeface(typeface);
        textView.setTextColor(color);      
        return textView;
    }

This code was written by someone and I thought of writing unit test case for this.

I wrote a test case something like:

Context ctx = ShadowApplication.getInstance().getApplicationContext();
TextView tv = Foo.constructTextView(ctx,...);

How do I mock Typeface here as the Context object itself is mocked or something?

Do you think I need to set typeface as one of the arguments to the method than creating it in the method itself to mock it?

What I found is that when the method gets called by the test case class, the line

Typeface.createFromAsset(context.getAssets(),"fonts/" + font); fails to run.