Throwables.java
package androidx.test.services.events.internal;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.AbstractList;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
/**
* Copy of org.junit.internal.Throwables#getTrimmedStackTrace from
* https://github.com/junit-team/junit4/pull/1028
*
* <p>TODO(b/128614857): Remove once androidx.test can use JUnit 4.13 directly
*/
final class Throwables {
private Throwables() {}
/**
* Gets a trimmed version of the stack trace of the given exception. Stack trace elements that are
* below the test method are filtered out.
*
* @return a trimmed stack trace, or the original trace if trimming wasn't possible
*/
public static String getTrimmedStackTrace(Throwable exception) {
List<String> trimmedStackTraceLines = getTrimmedStackTraceLines(exception);
if (trimmedStackTraceLines.isEmpty()) {
return getFullStackTrace(exception);
}
StringBuilder result = new StringBuilder(exception.toString());
appendStackTraceLines(trimmedStackTraceLines, result);
appendStackTraceLines(getCauseStackTraceLines(exception), result);
return result.toString();
}
private static List<String> getTrimmedStackTraceLines(Throwable exception) {
List<StackTraceElement> stackTraceElements = Arrays.asList(exception.getStackTrace());
int linesToInclude = stackTraceElements.size();
State state = State.PROCESSING_OTHER_CODE;
for (StackTraceElement stackTraceElement : asReversedList(stackTraceElements)) {
state = state.processStackTraceElement(stackTraceElement);
if (state == State.DONE) {
List<String> trimmedLines = new ArrayList<String>(linesToInclude + 2);
trimmedLines.add("");
for (StackTraceElement each : stackTraceElements.subList(0, linesToInclude)) {
trimmedLines.add("\tat " + each);
}
if (exception.getCause() != null) {
trimmedLines.add(
"\t... " + (stackTraceElements.size() - trimmedLines.size()) + " trimmed");
}
return trimmedLines;
}
linesToInclude--;
}
return Collections.emptyList();
}
private static List<String> getCauseStackTraceLines(Throwable exception) {
if (exception.getCause() != null) {
String fullTrace = getFullStackTrace(exception);
BufferedReader reader =
new BufferedReader(new StringReader(fullTrace.substring(exception.toString().length())));
List<String> causedByLines = new ArrayList<String>();
try {
String line;
while ((line = reader.readLine()) != null) {
if (line.startsWith("Caused by: ")) {
causedByLines.add(line);
while ((line = reader.readLine()) != null) {
causedByLines.add(line);
}
return causedByLines;
}
}
} catch (IOException e) {
// We should never get here, because we are reading from a StringReader
}
}
return Collections.emptyList();
}
private static String getFullStackTrace(Throwable exception) {
StringWriter stringWriter = new StringWriter();
PrintWriter writer = new PrintWriter(stringWriter);
exception.printStackTrace(writer);
return stringWriter.toString();
}
private static void appendStackTraceLines(
List<String> stackTraceLines, StringBuilder destBuilder) {
for (String stackTraceLine : stackTraceLines) {
destBuilder.append(String.format("%s%n", stackTraceLine));
}
}
private static <T> List<T> asReversedList(final List<T> list) {
return new AbstractList<T>() {
@Override
public T get(int index) {
return list.get(list.size() - index - 1);
}
@Override
public int size() {
return list.size();
}
};
}
private enum State {
PROCESSING_OTHER_CODE {
@Override
public State processLine(String methodName) {
if (isTestFrameworkMethod(methodName)) {
return PROCESSING_TEST_FRAMEWORK_CODE;
}
return this;
}
},
PROCESSING_TEST_FRAMEWORK_CODE {
@Override
public State processLine(String methodName) {
if (isReflectionMethod(methodName)) {
return PROCESSING_REFLECTION_CODE;
} else if (isTestFrameworkMethod(methodName)) {
return this;
}
return PROCESSING_OTHER_CODE;
}
},
PROCESSING_REFLECTION_CODE {
@Override
public State processLine(String methodName) {
if (isReflectionMethod(methodName)) {
return this;
} else if (isTestFrameworkMethod(methodName)) {
// This is here to handle TestCase.runBare() calling TestCase.runTest().
return PROCESSING_TEST_FRAMEWORK_CODE;
}
return DONE;
}
},
DONE {
@Override
public State processLine(String methodName) {
return this;
}
};
/** Processes a stack trace element method name, possibly moving to a new state. */
protected abstract State processLine(String methodName);
/** Processes a stack trace element, possibly moving to a new state. */
public final State processStackTraceElement(StackTraceElement element) {
return processLine(element.getClassName() + "." + element.getMethodName() + "()");
}
}
private static final String[] TEST_FRAMEWORK_METHOD_NAME_PREFIXES = {
"org.junit.runner.",
"org.junit.runners.",
"org.junit.experimental.runners.",
"org.junit.internal.",
"junit.",
};
private static final String[] TEST_FRAMEWORK_TEST_METHOD_NAME_PREFIXES = {
"org.junit.internal.StackTracesTest",
};
private static boolean isTestFrameworkMethod(String methodName) {
return isMatchingMethod(methodName, TEST_FRAMEWORK_METHOD_NAME_PREFIXES)
&& !isMatchingMethod(methodName, TEST_FRAMEWORK_TEST_METHOD_NAME_PREFIXES);
}
private static final String[] REFLECTION_METHOD_NAME_PREFIXES = {
"sun.reflect.",
"java.lang.reflect.",
// ANDROID-CHANGED - filter jdk 11
"jdk.internal.reflect.",
"org.junit.rules.RunRules.<init>(",
"org.junit.rules.RunRules.applyAll(", // calls TestRules
"org.junit.runners.BlockJUnit4ClassRunner.withMethodRules(", // calls MethodRules
"junit.framework.TestCase.runBare(", // runBare() directly calls setUp() and tearDown()
};
private static boolean isReflectionMethod(String methodName) {
return isMatchingMethod(methodName, REFLECTION_METHOD_NAME_PREFIXES);
}
private static boolean isMatchingMethod(String methodName, String[] methodNamePrefixes) {
for (String methodNamePrefix : methodNamePrefixes) {
if (methodName.startsWith(methodNamePrefix)) {
return true;
}
}
return false;
}
}