我想为解析器编写单元测试,并希望检查它是否正确地为列表中的所有输入字符串抛出异常。根据我的理解,使用 JUnit 的标准方法是为每个案例编写一个单独的测试方法:
public final class ParseFailureTest1 {
@Test(expected = ParseException.class)
public void testParseFailure1() throws Exception {
Parser.parse("[1 2]"); // Missing comma
}
@Test(expected = ParseException.class)
public void testParseFailure2() throws Exception {
Parser.parse("[1, 2,]"); // Additional commas
}
}
但是,由于我想将相同的测试应用于20或50个不同的字符串,这似乎是不切实际的。
另一种方法是使用catch
块明确检查异常:
public final class ParseFailureTest2 {
@Test
public void testParseFailure() throws Exception {
List<String> documents = Arrays.asList(
"[1 2]", // Missing comma
"[1, 2,]"); // Additional commas
for (String document : documents) {
try {
Parser.parse(document);
throw new AssertionError("Exception was not thrown");
} catch (ParseException e) {
// Expected, do nothing.
}
}
}
}
但是这很容易出错,我不会得到任何关于预期的异常的信息,如果抛出了不同的异常,它将被视为测试错误,而不是失败。
我的解决方案是使用类似于以下expectException
的方法:
public final class ParseFailureTest3 {
@Test
public void testParseFailure() throws Exception {
List<String> documents = Arrays.asList(
"[1 2]", // Missing comma
"[1, 2,]"); // Additional commas
for (final String document : documents) {
expectException(ParseException.class, new TestRunnable() {
@Override
public void run() throws Throwable {
Parser.parse(document);
}
});
}
}
public static void expectException(Class<? extends Throwable> expected, TestRunnable test) {
try {
test.run();
} catch (Throwable e) {
if (e.getClass() == expected) {
return; // Expected, do nothing.
} else {
throw new AssertionError(String.format("Wrong exception was thrown: %s instead of %s", e.getClass(), expected), e);
}
}
throw new AssertionError(String.format("Expected exception was not thrown: %s", expected));
}
public interface TestRunnable {
void run() throws Throwable;
}
}
在JUnit框架或相关库中是否存在用于此目的的方法,或者您是否会针对该问题提出不同的方法(或我拒绝的方法之一)?
答案 0 :(得分:3)
使用JUnit4进行参数化测试功能。以下代码应该可以使用。
import java.util.Arrays;
import java.util.Collection;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;
@RunWith(value = Parameterized.class)
public class ParseTest {
private String parseValue;
public ParseTest(String parseValue) {
this.parseValue = parseValue;
}
@Parameters
public static Collection<Object[]> data() {
Object[][] data = new Object[][] { { "[1 2]" }, { "[1,2,]" } };
return Arrays.asList(data);
}
@Test(expected = ParseException.class)
public void testParseFailure1() throws Exception {
Parse.parse(parseValue);
}
}
有关详细信息,请参阅http://www.mkyong.com/unittest/junit-4-tutorial-6-parameterized-test/
答案 1 :(得分:2)
使用fail()
方法:
@Test
public void testParseFailure() throws Exception {
List<String> documents = Arrays.asList(
"[1 2]", // Missing comma
"[1, 2,]"); // Additional commas
for (String document : documents) {
try {
Parser.parse(document);
fail("Parsing " + document + " should have thrown a ParseException");
}
catch (ParseException e) {
// Expected, do nothing.
}
}
}
答案 2 :(得分:0)
如果您关心在异常中获取正确的消息,那么这是另一种选择,保留前一个答案的fail
想法。
public final class ParseFailureTest {
@Test
public void testParseFailure() throws Exception {
Map<String, String> documents = new LinkedHashMap<String,String>();
documents.put("[1 2]", "Missing comma");
documents.put("[1, 2,]", "Additional commas");
for (Entry<String,String> entry : documents.entrySet()) {
try {
Parser.parse(entry.getKey());
fail("Parsing " + entry.getKey() +
" should have thrown a ParseException");
} catch (ParseException e) {
assertEquals(entry.getValue(), e.getMessage());
}
}
}
}