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| 1 | +package org.junit.internal; |
| 2 | + |
| 3 | +import java.io.BufferedReader; |
| 4 | +import java.io.IOException; |
| 5 | +import java.io.PrintWriter; |
| 6 | +import java.io.StringReader; |
| 7 | +import java.io.StringWriter; |
| 8 | +import java.util.AbstractList; |
| 9 | +import java.util.ArrayList; |
| 10 | +import java.util.Collections; |
| 11 | +import java.util.List; |
| 12 | + |
| 13 | +/** |
| 14 | + * Utility class for working with stack traces. |
| 15 | + */ |
| 16 | +public class StackTraces { |
| 17 | + private StackTraces() { |
| 18 | + } |
| 19 | + |
| 20 | + /** |
| 21 | + * Gets a trimmed version of the stack trace of the given exception. Stack trace |
| 22 | + * elements that are below the test method are filtered out. |
| 23 | + * |
| 24 | + * @return a trimmed stack trace, or the original trace if trimming wasn't possible |
| 25 | + */ |
| 26 | + public static String getTrimmedStackTrace(Throwable exception) { |
| 27 | + StringWriter stringWriter = new StringWriter(); |
| 28 | + PrintWriter writer = new PrintWriter(stringWriter); |
| 29 | + exception.printStackTrace(writer); |
| 30 | + return trimStackTrace(exception.toString(), stringWriter.toString()); |
| 31 | + } |
| 32 | + |
| 33 | + /** |
| 34 | + * Trims the given stack trace. Stack trace elements that are below the test method are |
| 35 | + * filtered. out. |
| 36 | + * |
| 37 | + * @param fullTrace the full stack trace |
| 38 | + * @return a trimmed stack trace, or the original trace if trimming wasn't possible |
| 39 | + */ |
| 40 | + public static String trimStackTrace(String fullTrace) { |
| 41 | + return trimStackTrace("", fullTrace); |
| 42 | + } |
| 43 | + |
| 44 | + static String trimStackTrace(String extracedExceptionMessage, String fullTrace) { |
| 45 | + StringBuilder trimmedTrace = new StringBuilder(extracedExceptionMessage); |
| 46 | + BufferedReader reader = new BufferedReader( |
| 47 | + new StringReader(fullTrace.substring(extracedExceptionMessage.length()))); |
| 48 | + |
| 49 | + try { |
| 50 | + // Collect the stack trace lines for "exception" (but not the cause). |
| 51 | + List<String> stackTraceLines = new ArrayList<String>(); |
| 52 | + String line; |
| 53 | + boolean hasCause = false; |
| 54 | + while ((line = reader.readLine()) != null) { |
| 55 | + if (line.startsWith("Caused by: ")) { |
| 56 | + hasCause= true; |
| 57 | + break; |
| 58 | + } |
| 59 | + stackTraceLines.add(line); |
| 60 | + } |
| 61 | + if (stackTraceLines.isEmpty()) { |
| 62 | + // No stack trace? |
| 63 | + return fullTrace; |
| 64 | + } |
| 65 | + stackTraceLines = trimStackTraceLines(stackTraceLines, hasCause); |
| 66 | + if (stackTraceLines.isEmpty()) { |
| 67 | + // Could not trim stack trace lines. |
| 68 | + return fullTrace; |
| 69 | + } |
| 70 | + appendStackTraceLines(stackTraceLines, trimmedTrace); |
| 71 | + if (line != null) { |
| 72 | + // Print remaining stack trace lines. |
| 73 | + do { |
| 74 | + trimmedTrace.append(line).append("\n"); |
| 75 | + line = reader.readLine(); |
| 76 | + } while (line != null); |
| 77 | + } |
| 78 | + return trimmedTrace.toString(); |
| 79 | + } catch (IOException e) { |
| 80 | + } |
| 81 | + return fullTrace; |
| 82 | + } |
| 83 | + |
| 84 | + private static void appendStackTraceLines( |
| 85 | + List<String> stackTraceLines, StringBuilder destBuilder) { |
| 86 | + for (String stackTraceLine : stackTraceLines) { |
| 87 | + destBuilder.append(stackTraceLine).append("\n"); |
| 88 | + } |
| 89 | + } |
| 90 | + |
| 91 | + private static List<String> trimStackTraceLines( |
| 92 | + List<String> stackTraceLines, boolean hasCause) { |
| 93 | + State state = State.PROCESSING_OTHER_CODE; |
| 94 | + int linesToInclude = stackTraceLines.size(); |
| 95 | + for (String stackTraceLine : asReversedList(stackTraceLines)) { |
| 96 | + state = state.processLine(stackTraceLine); |
| 97 | + if (state == State.DONE) { |
| 98 | + List<String> trimmedLines = stackTraceLines.subList(0, linesToInclude); |
| 99 | + if (!hasCause) { |
| 100 | + return trimmedLines; |
| 101 | + } |
| 102 | + List<String> copy = new ArrayList<String>(trimmedLines); |
| 103 | + copy.add("\t..." + (stackTraceLines.size() - copy.size()) + "more"); |
| 104 | + return copy; |
| 105 | + } |
| 106 | + linesToInclude--; |
| 107 | + } |
| 108 | + return Collections.emptyList(); |
| 109 | + } |
| 110 | + |
| 111 | + private static <T> List<T> asReversedList(final List<T> list) { |
| 112 | + return new AbstractList<T>() { |
| 113 | + |
| 114 | + @Override |
| 115 | + public T get(int index) { |
| 116 | + return list.get(list.size() - index - 1); |
| 117 | + } |
| 118 | + |
| 119 | + @Override |
| 120 | + public int size() { |
| 121 | + return list.size(); |
| 122 | + } |
| 123 | + }; |
| 124 | + } |
| 125 | + |
| 126 | + private enum State { |
| 127 | + PROCESSING_OTHER_CODE { |
| 128 | + @Override public State processLine(String line) { |
| 129 | + if (isTestFrameworkStackTraceLine(line)) { |
| 130 | + return PROCESSING_TEST_FRAMEWORK_CODE; |
| 131 | + } |
| 132 | + return this; |
| 133 | + } |
| 134 | + }, |
| 135 | + PROCESSING_TEST_FRAMEWORK_CODE { |
| 136 | + @Override public State processLine(String line) { |
| 137 | + if (isReflectionStackTraceLine(line)) { |
| 138 | + return PROCESSING_REFLECTION_CODE; |
| 139 | + } else if (isTestFrameworkStackTraceLine(line)) { |
| 140 | + return this; |
| 141 | + } |
| 142 | + return PROCESSING_OTHER_CODE; |
| 143 | + } |
| 144 | + }, |
| 145 | + PROCESSING_REFLECTION_CODE { |
| 146 | + @Override public State processLine(String line) { |
| 147 | + if (isReflectionStackTraceLine(line)) { |
| 148 | + return this; |
| 149 | + } else if (isTestFrameworkStackTraceLine(line)) { |
| 150 | + /* |
| 151 | + * This is here to handle TestCase.runBare() calling TestCase.runTest(). |
| 152 | + * We could in theory get here if a built-in rule is accessed via |
| 153 | + * reflection. |
| 154 | + */ |
| 155 | + return PROCESSING_TEST_FRAMEWORK_CODE; |
| 156 | + } |
| 157 | + return DONE; |
| 158 | + } |
| 159 | + }, |
| 160 | + DONE { |
| 161 | + @Override public State processLine(String line) { |
| 162 | + return this; |
| 163 | + } |
| 164 | + }; |
| 165 | + |
| 166 | + /** Processes a stack trace line, possibly moving to a new state. */ |
| 167 | + public abstract State processLine(String line); |
| 168 | + } |
| 169 | + |
| 170 | + private static final String[] TEST_FRAMEWORK_METHOD_NAME_PREFIXES = { |
| 171 | + "org.junit.runner.", |
| 172 | + "org.junit.runners.", |
| 173 | + "org.junit.experimental.runners.", |
| 174 | + "org.junit.internal.", |
| 175 | + "junit.", |
| 176 | + "org.apache.maven.surefire." |
| 177 | + }; |
| 178 | + |
| 179 | + private static boolean isTestFrameworkStackTraceLine(String line) { |
| 180 | + return isMatchingStackTraceLine(line, TEST_FRAMEWORK_METHOD_NAME_PREFIXES); |
| 181 | + } |
| 182 | + |
| 183 | + private static final String[] REFLECTION_METHOD_NAME_PREFIXES = { |
| 184 | + "sun.reflect.", |
| 185 | + "java.lang.reflect.", |
| 186 | + "org.junit.rules.RunRules.evaluate(", // get better stack traces for failures in method rules |
| 187 | + "junit.framework.TestCase.runBare(", // runBare() directly calls setUp() and tearDown() |
| 188 | + }; |
| 189 | + |
| 190 | + private static boolean isReflectionStackTraceLine(String line) { |
| 191 | + return isMatchingStackTraceLine(line, REFLECTION_METHOD_NAME_PREFIXES); |
| 192 | + } |
| 193 | + |
| 194 | + private static boolean isMatchingStackTraceLine(String line, String[] packagePrefixes) { |
| 195 | + if (!line.startsWith("\tat ")) { |
| 196 | + return false; |
| 197 | + } |
| 198 | + line = line.substring(4); |
| 199 | + for (String packagePrefix : packagePrefixes) { |
| 200 | + if (line.startsWith(packagePrefix)) { |
| 201 | + return true; |
| 202 | + } |
| 203 | + } |
| 204 | + |
| 205 | + return false; |
| 206 | + } |
| 207 | +} |
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