ViewHierarchyExceptionHandler.java
/*
* Copyright (C) 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.test.espresso.base;
import static androidx.test.internal.util.Checks.checkNotNull;
import static com.google.common.base.Throwables.throwIfUnchecked;
import android.util.Log;
import android.view.View;
import androidx.test.espresso.RootViewException;
import androidx.test.espresso.base.DefaultFailureHandler.TypedFailureHandler;
import androidx.test.espresso.util.EspressoOptional;
import androidx.test.espresso.util.HumanReadables;
import androidx.test.platform.io.PlatformTestStorage;
import androidx.test.services.storage.TestStorageException;
import java.io.IOException;
import java.io.OutputStream;
import java.util.concurrent.atomic.AtomicInteger;
import org.hamcrest.Matcher;
/**
* An Espresso failure handler that handles a {@link RootViewException} to dump the full view
* hierarchy to an artifact file.
*/
class ViewHierarchyExceptionHandler<T extends Throwable & RootViewException>
extends TypedFailureHandler<T> {
private static final String TAG = ViewHierarchyExceptionHandler.class.getSimpleName();
// Max stack length that can be printed without being truncated in android log. Used to
// display a truncated version of the view hierarchy and still have some extra room for the
// stack trace.
private static final int MAX_MSG_SIZE = (64 - 2) * 1024;
private static final String VIEW_HIERARCHY_CHAR_LIMIT = "view_hierarchy_char_limit";
private final PlatformTestStorage testStorage;
private final AtomicInteger failureCount;
private final Truncater<T> truncater;
interface Truncater<T> {
Throwable truncateExceptionMessage(
T exception, int msgLen, EspressoOptional<String> viewHierarchyFile);
}
public ViewHierarchyExceptionHandler(
PlatformTestStorage testStorage,
AtomicInteger failureCount,
Class<T> expectedType,
Truncater<T> truncater) {
super(expectedType);
this.testStorage = checkNotNull(testStorage);
this.failureCount = failureCount;
this.truncater = truncater;
}
@Override
public void handleSafely(T exception, Matcher<View> viewMatcher) {
EspressoOptional<String> viewHierarchyFile = dumpFullViewHierarchyToFile(exception);
exception.setStackTrace(Thread.currentThread().getStackTrace());
int msgLen = getMsgLen();
// Truncate exception message to fit within a printable stack frame dump.
Throwable error = truncater.truncateExceptionMessage(exception, msgLen, viewHierarchyFile);
throwIfUnchecked(error);
throw new RuntimeException(error);
}
private int getMsgLen() {
try {
if (testStorage.getInputArgs().containsKey(VIEW_HIERARCHY_CHAR_LIMIT)) {
String limit = testStorage.getInputArg(VIEW_HIERARCHY_CHAR_LIMIT);
if (limit != null) {
return Integer.parseInt(limit);
}
}
} catch (NumberFormatException | TestStorageException e) {
Log.e(TAG, "Failed to parse input argument " + VIEW_HIERARCHY_CHAR_LIMIT, e);
}
return MAX_MSG_SIZE;
}
private EspressoOptional<String> dumpFullViewHierarchyToFile(T error) {
String viewHierarchyMsg =
HumanReadables.getViewHierarchyErrorMessage(
error.getRootView(),
/* problemViews= */ null,
/* errorHeader= */ "",
/* problemViewSuffix= */ null);
String viewHierarchyFile = "view-hierarchy-" + failureCount + ".txt";
try {
addOutputFile(viewHierarchyFile, viewHierarchyMsg);
Log.w(
TAG,
"The complete view hierarchy is available in artifact file '" + viewHierarchyFile + "'.");
return EspressoOptional.of(viewHierarchyFile);
} catch (IOException e) {
// Log and ignore.
Log.w(TAG, "Failed to save the view hierarchy to file " + viewHierarchyFile, e);
return EspressoOptional.absent();
}
}
private void addOutputFile(String filename, String content) throws IOException {
try (OutputStream out = testStorage.openOutputFile(filename)) {
out.write(content.getBytes());
}
}
}