Junit 5 extension - how to access testDescriptor - java

I am writing an extension for a test using #ParameterizedTest. My test looks like:
#ParameterizedTest
#ValueSource(strings={"string1", "string2"})
public void test1(String name){
System.out.println(name);
}
In the extensions, how do I get the TestDesciptor to find out which invocation in currently active?
public class MyExtension implements BeforeEachCallBack{
#Override
public void beforeEach(ExtensionContext extensionContext)
// What to do here? extensionContext.?
}
}

As you can see by its package name org.junit.platform.engine.TestDescriptor is not part of JUnit Jupiter API which has org.junit.jupiter.api as its base package. Moreover, org.junit.platform.engine is not even imported by the API.
So the sad answer is you cannot get at the test descriptor, at least not without some dirty and unstable reflection. I am, however, quite sure that the underlying reason you have for wanting access can be mitigated in a different way. So what is it you’d like to achieve?

Related

How to create method that could be used only for tests

Are the any ways to create method/contractor that could be used only in Junit ( test purpose only ) ?
Maybe there is an annotation?
For methods that are only used for testing... why not make them part of the actual test-code? At least in build-systems such as Maven, test code is not included in packaged jars, and is only distributed as part of the sources. In that sense, it cannot be called from normal classes, since it is simply not included in the final .jar (or .war).
I very frequently write such methods to make my test-code more maintainable.
To clarify:
src/
main/
java/
my/package/
MyClass.java <-- leave necessary protected accessors here
test/
java/
my/package/
MyClassTest.java <-- implement test-code here
And in MyClassTest...
public class MyClassTest {
...
private static Foo doSomethingCoolButTesty(MyClass instance) {
// access protected or package-private MyClass code here
}
}
MyClassTest.doSomethingCoolButTesty will be kept separate from the main code, and will obviously only be available to test code. Yes, it is somewhat uglier than including it as a method of the main code, but I find a fair price to pay.
For what purpose do you need this method?
(J)UnitTests should verify the behavior of the class by using its public interface. No "special" method in the tested code should be used in unit tests.
But Unittests should replace the dependencies of the tested code with test doubles (aka fakes and mocks). The preferred way to provide those test doubles is dependency injection (DI).
Sometimes its to much effort to introduce DI to your code. In that case it is acceptable to introduce low visibility getter methods as a seam where the dependency can be replaced by the mock.
class CodeUnderTest{
private final SomeOtherClass dependency = new SomeOtherClass();
SomeOtherClass getDependency(){ // package private getter
return dependency;
}
public void doSomething(){
dependency.expectedMethodCalled();
}
}
class TestInSamePackage{
#Rule
public MockitoRule rule = MockitoJUnit.rule();
#Mock
private SomeOtherClass testDouble;
#Spy
private CodeUnderTest cut;
#Before
public void setup(){
doReturn(testDouble).when(cut).getDependency();
}
#Test
public void shouldDoSomething() {
// configure testDouble
cut.doSomething();
verify(testDouble).expectedMethodCalled();
}
}
There is nothing that would prevent to call methods "outside" of a junit test case.
My pragmatic answer: make the method package protected and add a simple comment like "unit test only" as javadoc. And educate your team to honor such statements.
And ideally: design your production code in a way that does not require such "tricks" in order to make it testable!
Given the comments on the question: it might be technically possible to somehow acquire stack trace information; to then search for the presence of #Test annotations on the corresponding methods. But that seems to be absolute overkill - and it would mean to add even more "test only" code into the production code.
And it would also be the wrong approach - as it tries to solve a "social" problem using technical means: if you don't want that people are calling a certain method - then make sure they understand that.

How do I get an outline specification in Java JUnit?

I'm looking for the ability to nest JUnit tests. I found #RunWith(Enclosed.class), but it only runs one level inclosed and other tests aren't run.
Never mind, I found the answer over here: NitorCreations Nested Runner
This is exactly what I was looking for. It allows JUnit tests to be fully nested.
Because NestedRunner tests did not properly visualize test names in my IntelliJ IDEA I am using HierarchicalContextRunner instead
It provides exactly the same functionality. Just swap them in the #RunWith if you are not happy with how your IDE is showing your tests.
Here is an example of what was wrong:
#RunWith(NestedRunner.class)
public class ATest {
#Test
public void haveARegularTestsInside() {}
public class hasASubClass {
#Test
public void thatHasTests() {}
}
}
looks like this:
Here I expected to have thatHasTests at the last line, but got the whole AClass$hasASubClass.thatHasTests.
change #RunWith to HierarchicalContextRunner and what you get is now this:
Better, isn't it?

getting TestNG to treat class variables like JUnit with Guice

I am trying to setup TestNG so that it gives me new instances of my class variable for each test (basically like JUnit). I need this as I intend to parallelize my tests at the method level. I have been experimenting with both standalone Guice and the built in Guice functionality that TestNG provides to try to accomplish this but I have had no luck. I know that I can use ThreadLocal, but calling .get() for every variable in the test is pretty unappealing. I am weary of using GuiceBerry as it does not really have a lot of updates/activity and it's last release is not even acquirable via Maven. I am pretty set on TestNG as for all the inconvenience this is causing me it still does a lot of great things. I am open to things other tools though to accomplish my goal. Basically I want things setup so the below tests would work consistently. Any help would be greatly appreciated.
// just has a variable thats a class called child with a simple string variable
// with a value of "original
Parent p;
#Test
public void sometest1(){
p.child.value = "Altered";
Assert.assertTrue(p.child.value.equals("Altered"));
}
#Test
public void sometest2(){
Assert.assertTrue(p.child.value.equals("original"));
}
TestNG doesn't create a new instance for each test. If you want such a behavior than I recommend creating separate test classes. e.g.:
public class SomeTest1 {
Parent p;
#Test
public void something(){
p.child.value = "Altered";
Assert.assertTrue(p.child.value.equals("Altered"));
}
}
public class SomeTest2 {
Parent p;
#Test
public void something(){
Assert.assertTrue(p.child.value.equals("original"));
}
}
Note that TestNG can run JUnit 3 and JUnit 4 tests (you might maintain a mixed suite depending on the style you want to use in a given test class).

jUnit4.0 : how to know current test method name?

I've implemented a feature in my jUnit tests that takes, for every test case, a fresh copy of a data source. This copy is taken in a folder specific for each test case. The idea is that every test case can start from a clean situation, manipulate it and let it as such after the run. This is often useful when the test fails for analysing the problem.
For now I have to call this feature directly in the test method because I don't know how to retrieve the current test name:
public void testTest1() {
TestHelper th=TestHelper.create("testTest1",subPathToDataSource);
// do the test...
Path dataPath = th.getDataPath();
...
}
I would like to be able to write something like this:
Path dataPath;
#Before
public initTest() {
th=TestHelper.create(SomeJUnitObject.getCurrentTestName(),subPathToDataSource);
...
}
public void testTest1() {
// do the test...
Path dataPath = th.getDataPath();
...
}
Until now I found as answers : "You don't need to know that"... But I do need it !
Is this possible ?
Kind regards
Look at the TestName rule.
You should be able to add in your test class:
#Rule TestName name=new TestName();
And then access it.
(On phone, so can't check versions support/details - might be 4.x only)
Here is an alternative approach; create an abstract class which your "real" test classes inherit.
I have several such examples in my projects and here I will give one, mainly testing for individual JSON Patch operations.
All my test files are JSON, and located under an appropriately named resource directory. The base, abstract class is JsonPatchOperationTest. And here is the full code of AddOperationTest which tests for JSON Patch's add operation:
public final class AddOperationTest
extends JsonPatchOperationTest
{
public AddOperationTest()
throws IOException
{
super("add");
}
}
And that's it! Not even one test method in this class, but of course your implementation may vary.
In your case you probably want to pass the directory name as a constructor argument, or the like.

Mock System class to get system properties

I have a folder path set in system variable through JVM arguments in Eclipse and I am trying to access it in my class as:
System.getProperty("my_files_path").
While writing junit test method for this class, I tried mocking this call as test classes do not consider JVM arguments. I have used PowerMockito to mock static System class and tried returning some path when System.getProperpty is being called.
Had #RunWith(PowerMockRunner.class) and #PrepareForTest(System.class) annotations at class level. However, System class is not getting mocked as a result I always get null result.
Any help is appreciated.
Thanks Satish. This works except with a small modification. I wrote PrepareForTest(PathFinder.class), preparing the class I am testing for test cases instead of System.class
Also, as mock works only once, I called my method right after mocking.
My code just for reference:
#RunWith(PowerMockRunner.class)
#PrepareForTest(PathInformation.class)
public class PathInformationTest {
private PathFinder pathFinder = new PathFinder();
#Test
public void testValidHTMLFilePath() {
PowerMockito.mockStatic(System.class);
PowerMockito.when(System.getProperty("my_files_path")).thenReturn("abc");
assertEquals("abc",pathFinder.getHtmlFolderPath());
}
}
There are certain classes PowerMock can't mock in the usual way. See here:
https://code.google.com/p/powermock/wiki/MockSystem
This, however, may still not work. In order of "good design" preference, you can fall back to these:
Refactor your code! Using a System property for passing a file path around is probably not the best way. Why not use a properties file loaded into a Properties object? Why not use getters/setters for the components that need to know this path? There are many better ways to do this.
The only reason I could think of not to do this is you're trying to wrap a test harness around code you "can't" modify.
Use #Before and #After methods to set the System property to some known value for the test(s). You could even make it part of the #Test method itself. This will be FAR easier than attempting to mock through PowerMock. Just call System.setProperty("my_files_path","fake_path");
System class is declared as final and cannot be mocked by libraries such as PowerMock. Several answers posted here are incorrect. If you are using Apache System Utils you can use getEnvironmentVariable method instead of calling System.getenv directly. SystemUtils can be mocked since it is not declared as final.
Set the system property in your test and ensure that it is restored after the test by using the rule RestoreSystemProperties of the library System Rules.
public class PathInformationTest {
private PathFinder pathFinder = new PathFinder();
#Rule
public TestRule restoreSystemProperties = new RestoreSystemProperties();
#Test
public void testValidHTMLFilePath() {
System.setProperty("my_files_path", "abc");
assertEquals("abc",pathFinder.getHtmlFolderPath());
}
}
The System.setter or getter method should be put in a user defined method and that method can be mocked to return the desired property in unit test.
public String getSysEnv(){
return System.getEnv("thisprp");
}
#RunWith(PowerMockRunner.class)
#PrepareForTest(System.class)
public class MySuperClassTest {
#Test
public void test(){
PowerMockito.mockStatic(System.class);
PowerMockito.when(System.getProperty("java.home")).thenReturn("abc");
System.out.println(System.getProperty("java.home"));
}
}
Sailaja add System.class because as per the power mock guidelines for static,private mocking you should add the class in prepare for test.
#PrepareForTest({PathInformation.class,System.class})
Hope this helps.let me know if it doesn't work

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