断言，对于在方法层面已经被捕获的一场，没法通过单元测试再次捕获异常，可以通过sys-rules对控制台的ERROR、OUT信息进行捕获，从而进行断言
System Rules is a collection of JUnit rules for testing code which uses `java.lang.System`.
# System Rules
Linux(https://travis-ci.org/stefanbirkner/system-rules.svg?branch=master)](https://travis-ci.org/stefanbirkner/system-rules)
Windows(https://ci.appveyor.com/api/projects/status/vr0c93rssc6mhetl/branch/master?svg=true)](https://ci.appveyor.com/project/stefanbirkner/system-rules)
mvn依赖
<dependency>
<groupId>com.github.stefanbirkner</groupId>
<artifactId>system-rules</artifactId>
<version>1.18.0<version>
</dependency>
Please don't forget to add the scope `test` if you're using System Rules for tests only.
具体的使用参见UnitTest中TestException 类及AcceptanceTestRunner类
package com.XXX.XXXX;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.ClassRule;
import org.junit.Ignore;
import org.junit.internal.AssumptionViolatedException;
import org.junit.internal.runners.model.EachTestNotifier;
import org.junit.internal.runners.statements.RunAfters;
import org.junit.internal.runners.statements.RunBefores;
import org.junit.rules.RunRules;
import org.junit.rules.TestRule;
import org.junit.runner.Description;
import org.junit.runner.notification.Failure;
import org.junit.runner.notification.RunNotifier;
import org.junit.runners.BlockJUnit4ClassRunner;
import org.junit.runners.model.FrameworkMethod;
import org.junit.runners.model.InitializationError;
import org.junit.runners.model.Statement;
import org.junit.runners.model.TestClass;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Collection;
import java.util.List;
import static java.util.Collections.emptyList;
import static java.util.Collections.singleton;
public class AcceptanceTestRunner extends BlockJUnit4ClassRunner {
private static final Collection<Failure> NO_FAILURES = emptyList();
private final Method expectFailure;
private final Method verifyStateAfterTest;
private final Method verifyResult;
private final TestClass testClass;
public AcceptanceTestRunner(Class<?> testClass) throws InitializationError {
super(extractInnerTestClass(testClass));
expectFailure = extractMethod(testClass, "expectFailure", Failure.class);
verifyResult = extractMethod(testClass, "verifyResult", Collection.class);
verifyStateAfterTest = extractMethod(testClass, "verifyStateAfterTest");
this.testClass = new TestClass(testClass);
verifyCheckPresent();
}
private static Class<?> extractInnerTestClass(Class<?> testClass)
throws InitializationError {
Class<?>[] innerClasses = testClass.getClasses();
if (innerClasses.length > 1)
throw new InitializationError("The class " + testClass
+ " has " + innerClasses.length + " inner classes, but only"
+ " one inner class with name TestClass is expected.");
else if (innerClasses.length == 0
|| !innerClasses[0].getSimpleName().equals("TestClass"))
throw new InitializationError("The class " + testClass
+ " has no inner class with name TestClass.");
else
return innerClasses[0];
}
private void verifyCheckPresent() {
boolean noCheck = expectFailure == null
&& verifyResult == null
&& verifyStateAfterTest == null;
if (noCheck)
throw new IllegalStateException(
"No expectation is defined for the " + getName()
+ ". It needs either a method expectFailure, verifyResult or verifyStateAfterTest.");
}
private static Method extractMethod(Class<?> testClass, String name, Class<?>... parameterTypes) {
try {
return testClass.getMethod(name, parameterTypes);
} catch (NoSuchMethodException e) {
return null;
}
}
@Override
protected void runChild(final FrameworkMethod method, RunNotifier notifier) {
Description description = describeChild(method);
if (method.getAnnotation(Ignore.class) != null)
notifier.fireTestIgnored(description);
else
runTest(methodBlock(method), description, notifier);
}
protected Statement classBlock(final RunNotifier notifier) {
Statement statement = super.classBlock(notifier);
statement = withBeforeClasses(statement);
statement = withAfterClasses(statement);
statement = withClassRules(statement);
return statement;
}
protected Statement withBeforeClasses(Statement statement) {
List<FrameworkMethod> befores = testClass
.getAnnotatedMethods(BeforeClass.class);
return befores.isEmpty() ? statement :
new RunBefores(statement, befores, null);
}
protected Statement withAfterClasses(Statement statement) {
List<FrameworkMethod> afters = testClass
.getAnnotatedMethods(AfterClass.class);
return afters.isEmpty() ? statement :
new RunAfters(statement, afters, null);
}
private Statement withClassRules(Statement statement) {
List<TestRule> classRules = classRules();
return classRules.isEmpty() ? statement :
new RunRules(statement, classRules, getDescription());
}
protected List<TestRule> classRules() {
return testClass.getAnnotatedFieldValues(
null, ClassRule.class, TestRule.class);
}
private void runTest(Statement statement, Description description,
RunNotifier notifier) {
EachTestNotifier eachNotifier = new EachTestNotifier(notifier, description);
eachNotifier.fireTestStarted();
try {
statement.evaluate();
handleNoFailure(eachNotifier);
} catch (AssumptionViolatedException e) {
handleFailedAssumption(description, eachNotifier, e);
} catch (Throwable e) {
handleException(description, eachNotifier, e);
} finally {
invokeIfPresent(verifyStateAfterTest, eachNotifier);
eachNotifier.fireTestFinished();
}
}
private void handleNoFailure(EachTestNotifier eachNotifier) {
if (expectFailure != null)
eachNotifier.addFailure(new AssertionError("Test did not fail."));
invokeIfPresent(verifyResult, eachNotifier, NO_FAILURES);
}
private void handleFailedAssumption(Description description, EachTestNotifier eachNotifier, AssumptionViolatedException e) {
eachNotifier.addFailedAssumption(e);
if (expectFailure != null)
eachNotifier.addFailure(new AssertionError("Test did not fail."));
invokeIfPresent(
verifyResult, eachNotifier, singleton(new Failure(description, e)));
}
private void handleException(Description description, EachTestNotifier eachNotifier,
Throwable e) {
invokeIfPresent(
verifyResult, eachNotifier, singleton(new Failure(description, e)));
invokeIfPresent(
expectFailure, eachNotifier, new Failure(description, e));
if (expectFailure == null && verifyResult == null)
eachNotifier.addFailure(e);
}
private void invokeIfPresent(Method method, EachTestNotifier notifier, Object... args) {
if (method != null)
try {
method.invoke(null, args);
} catch (IllegalAccessException e) {
fail(notifier, e, "Failed to invoke '" + method.getName() + "'.");
} catch (InvocationTargetException e) {
fail(notifier, e, "Failed to invoke '" + method.getName() + "'.");
} catch (Exception e) {
notifier.addFailure(e);
}
}
private void fail(EachTestNotifier eachNotifier, InvocationTargetException e, String message) {
if (e.getCause() instanceof AssertionError)
eachNotifier.addFailure(e.getCause());
else
fail(eachNotifier, (Exception) e, message);
}
private void fail(EachTestNotifier eachNotifier, Exception e, String message) {
AssertionError error = new AssertionError(message);
error.initCause(e);
eachNotifier.addFailure(error);
}
}
// 在测试类里面添加如下信息
private final ByteArrayOutputStream outContent = new ByteArrayOutputStream();
private final ByteArrayOutputStream errContent = new ByteArrayOutputStream();
@Before
public void setUpStreams() {
System.setOut(new PrintStream(outContent));
System.setErr(new PrintStream(errContent));
}
/*需要添加pom依赖
* 需要@RunWith(AcceptanceTestRunner.class)
* 需要使用内部类
* 需要enableLog()
* */
@RunWith(AcceptanceTestRunner.class)
public static class catch_exception_through_system_rule {
public static class TestClass {
@Rule
public final SystemOutRule systemOutRule = new SystemOutRule();
@Rule
public final SystemErrRule systemErrRule = new SystemErrRule();
/*记得要toString*/
@org.junit.Test
public void test() {
System.out.print("text before enabling log");
systemOutRule.enableLog();
System.out.print("text after enabling log true\n \t \r 123456 ");
assertTrue(systemOutRule.getLog().toString().contains("text after enabling log"));
}
@org.junit.Test
public void testError() {
System.err.print("text before enabling log");
systemErrRule.enableLog();
System.err.print("text after enabling log");
assertTrue(systemErrRule.getLog().equals("text after enabling log"));
}
}
}
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