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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.cts.util;
     18 
     19 import android.content.Context;
     20 import android.content.pm.PackageManager;
     21 
     22 /**
     23  * Utilities to enable the android.webkit.* CTS tests (and others that rely on a functioning
     24  * android.webkit.WebView implementation) to determine whether a functioning WebView is present
     25  * on the device or not.
     26  *
     27  * Test cases that require android.webkit.* classes should wrap their first usage of WebView in a
     28  * try catch block, and pass any exception that is thrown to
     29  * NullWebViewUtils.determineIfWebViewAvailable. The return value of
     30  * NullWebViewUtils.isWebViewAvailable will then determine if the test should expect to be able to
     31  * use a WebView.
     32  */
     33 public class NullWebViewUtils {
     34 
     35     private static boolean sWebViewUnavailable;
     36 
     37     /**
     38      * @param context Current Activity context, used to query the PackageManager.
     39      * @param t       An exception thrown by trying to invoke android.webkit.* APIs.
     40      */
     41     public static void determineIfWebViewAvailable(Context context, Throwable t) {
     42         sWebViewUnavailable = !hasWebViewFeature(context) && checkCauseWasUnsupportedOperation(t);
     43     }
     44 
     45     /**
     46      * After calling determineIfWebViewAvailable, this returns whether a WebView is available on the
     47      * device and wheter the test can rely on it.
     48      * @return True iff. PackageManager determined that there is no WebView on the device and the
     49      *         exception thrown from android.webkit.* was UnsupportedOperationException.
     50      */
     51     public static boolean isWebViewAvailable() {
     52         return !sWebViewUnavailable;
     53     }
     54 
     55     private static boolean hasWebViewFeature(Context context) {
     56         // Query the system property that determins if there is a functional WebView on the device.
     57         PackageManager pm = context.getPackageManager();
     58         return pm.hasSystemFeature(PackageManager.FEATURE_WEBVIEW);
     59     }
     60 
     61     private static boolean checkCauseWasUnsupportedOperation(Throwable t) {
     62         if (t == null) return false;
     63         while (t.getCause() != null) {
     64             t = t.getCause();
     65         }
     66         return t instanceof UnsupportedOperationException;
     67     }
     68 
     69     /**
     70      * Some CTS tests (by design) first use android.webkit.* from a background thread. This helper
     71      * allows the test to catch the UnsupportedOperationException from that background thread, and
     72      * then query the result from the test main thread.
     73      */
     74     public static class NullWebViewFromThreadExceptionHandler
     75             implements Thread.UncaughtExceptionHandler {
     76         private Throwable mPendingException;
     77 
     78         @Override
     79         public void uncaughtException(Thread t, Throwable e) {
     80             mPendingException = e;
     81         }
     82 
     83         public boolean isWebViewAvailable(Context context) {
     84             return hasWebViewFeature(context) ||
     85                     !checkCauseWasUnsupportedOperation(mPendingException);
     86         }
     87     }
     88 }