I'm using Eclipse and JUnit 4 while developing an application within a tomcat container. The container manages the connection to our Oracle database.
While testing with JUnit i've got the following problem: In the constructor of the test subject there is something like this:
public Subject() {
// stuff
FancySingleton.getInstance().getFancy("stuff");
}
Unfortunately the method getFancy() tries to execute a Query which it can't because JUnit does not run within the tomcat container and ends up in an endless loop.
My first idea was to out-commend the code. At second thought it appeared to be a bad idea. I could forget to remove the comments before committing.
My second idea was to highlight the code for eclipse so that it doesn't execute it while running a JUnit test. But it requires eclipse to support such a method.
At last i thought of something like preprocessor directives.
What is your idea? Just passing in a boolean to the constructor is imho not a clean way of dealing with such a circumstance.
You'd either mock FancySingleton, or you'd do it right and inject an implementation.
Related
I'm using a Java lib within my Scala project. I want to call a specific static method adjustLib of that lib as early as possible and for every possible starting point of an execution (e.g. before runing the "main" App and before executing tests) to achieve the desired behaviour.
One solution would be to place this statement at the very top of each class, that might be executed (applies for all classes extending App and for all tests).
However, if someone implements a new, executable class but forgets adjustLib, things might get weird.
Is there any chance to define an object or something similar, that executes this adjustLib statement in a "static" manner every time anything in the given project is executed?
I am developing an eclipse plugin that runs code violation checker on the difference of two versions of a file. Right now I am using diff.exe to get the difference between the two files. But as diff.exe is an extrenal app, I realized that its better to use eclipse built-in compare tool to get the file difference.
So I used org.eclipse.compare and reached up to this point:
public static List<Patch> compare(String old, String recent) {
try{
IRangeComparator left = new TokenComparator(old); //what exactly to be passed in this constructor, a file path, a literal value or something else?
IRangeComparator right = new TokenComparator(recent);
RangeDifference[] diffs = RangeDifferencer.findDifferences(left, right); // This line is throwing NPE
//..
// Process RangeDifferences into Collection of Patch collection
//..
}catch(Exception e){}
//Returns a collection of file differences.
return null;
}
Now the problem is I am not sure what exactly to be passed in the constructor TokenComparator(String). The document says this constructor Creates a TokenComparator for the given string. But it is not written what exactly to be passed in this constructor, a file path, a literal value or something else? When I'm passing a file path or a string literal I am getting NullPointerException on the next line of finding differences.
java.lang.NullPointerException
at org.eclipse.compare.internal.core.LCS.isCappingDisabled(LCS.java:98)
at org.eclipse.compare.internal.core.LCS.longestCommonSubsequence(LCS.java:55)
at org.eclipse.compare.rangedifferencer.RangeComparatorLCS.longestCommonSubsequence(RangeComparatorLCS.java:186)
at org.eclipse.compare.rangedifferencer.RangeComparatorLCS.findDifferences(RangeComparatorLCS.java:31)
at org.eclipse.compare.rangedifferencer.RangeDifferencer.findDifferences(RangeDifferencer.java:98)
at org.eclipse.compare.rangedifferencer.RangeDifferencer.findDifferences(RangeDifferencer.java:82)
at org.eclipse.compare.rangedifferencer.RangeDifferencer.findDifferences(RangeDifferencer.java:67)
at com.dassault_systemes.eclipseplugin.codemonview.util.CodeMonDiff.compare(CodeMonDiff.java:48)
at com.dassault_systemes.eclipseplugin.codemonview.util.CodeMonDiff.main(CodeMonDiff.java:56)
Someone please tell what is right way to proceed.
If the question is What value the token comparators constructor takes then the answer is it takes the input string to compare. Specified in javadoc here http://help.eclipse.org/indigo/index.jsp?topic=%2Forg.eclipse.platform.doc.isv%2Freference%2Fapi%2Forg%2Feclipse%2Fcompare%2Fcontentmergeviewer%2FTokenComparator.html
TokenComparator(String text)
Creates a TokenComparator for the given string.
And the null pointer yo are getting is because in function isCappingDisabled it tries to open the compare plugin which seems to be null. You seem to be missing a direct dependency to the plugin "org.eclipse.compare.core"
The org.eclipse.compare plugin was never meant to be used in standalone : many of its functionalities require a running instance of Eclipse. Furthermore, it mixes core and UI code within the same plugin, which will lead to unexpected behavior if you are not very careful about what you use and what dependencies are actually available in your environment.
You mentionned that you were developping an Eclipse plugin. However, the NPE you get indicates that you are not running your code as an Eclipse plugin, but rather as a standard Java program. In an Eclipse environment, ComparePlugin.getDefault() cannot return null : the plugin needs to be started for that call to return anything but null.... and the mere loading of the ComparePlugin class within Eclipse is enough to start it.
The answer will be a choice :
You need your code to run as a standalone Java program out of Eclipse. In such an event, you cannot use org.eclipse.compare and diff.exe is probably your best choice (or you could switch to an implementation of diff that was implemented in Java in order to be independent of the platform).
You do not need your program to work in a standalone environment, only as an Eclipse plugin. In this case, you can keep the code you're using. However, when you run your code, you have to launch it as a new "Eclipse application" instead of "Java Application". You might want to look at a tutorial on how to develop Eclipse plugins for this, This simple tutorial from Lars Vogel shows how to run a new Eclipse Application to test an Hello World plugin. You will need a similar code, with a menu entry to launch your plugin somewhere (right-click on a file then select "check violations" in your case?).
There's support for forkMode in Ant and Maven and occasionally we use it with value perTest. However, the JUnit-tests in Eclipse still fail when we run the tests on a class or on a project (Run As -> JUnit Test). Obviously JUnit uses default settings or behaviour and executes the tests in parallel causing some red crosses in the JUnit-view.
Is there a way to code something into the test-class that lets JUnit behave like the forkMode setting? We don't mind if there's an Eclipse-only solution for this.
Or can this be done with a Run Configuration in Eclipse?
EDIT:
I understand that the problems are based on data remaining after tests and further tests will fail due to that. While this makes sense, please understand that this doesn't answer my question. Think of my situation as being part of some sort of a Tiger Team. We have a bunch of issues and fixing that part of existing tests is just one of them. Trust me, we will try to cover everything... (I haven't heard that in a while)
Eclipse runs the JUnit test serially, in a single thread, in the same JVM. If you have tests that normally operate in parallel, this should not affect the test behavior. However, if you assume that you can change settings in the VM, like system properties, or class static variables, and the next test will not have those changes, that will break your tests.
The rule of thumb is that each test should leave the system (vm, database, filesystem) exactly as it found it so that each test can be run at any time, in any order.
I am trying to do some integration testing in a Play! 2 for Scala application. For this, I need to load some fixtures to have the DB in a known state before each test.
At the moment, I am just invoking a method that executes a bunch of Squeryl statements to load data. But declaring the fixtures declaratively, either with a Scala DSL or in a language like JSON or YAML is more readable and easy to mantain.
In this example of a Java application I see that fixtures are loaded from a YAML file, but the equivalent Scala app resorts to manula loading, as I am doing right now.
I have also found this project which is not very well documented, and it seems a bit more complex than I'd like - it is not even clear to me where the fixture data is actually declared.
Are there any other options to load fixtures in a Play! application?
Use Evolutions. Write a setup and teardown script for the fixtures in SQL, or use mysqldump (or equivalent for your DB) to export an existing test DB as sql.
http://www.playframework.org/documentation/1.2/evolutions
I find the most stress-free way to do testing is to set everything up in an in-memory database which means tests run fast and drive the tests from Java using JUnit. I use H2DB, but there are a few gotchas you need to watch out for. I learned these the hard way, so this should save you some time.
Play has a nice system for setting up and tearing down your application for integration testing, using running( FakeAplication() ) { .. }, and you can configure it to use an in memory database with FakeApplication(additionalConfiguration = inMemoryDatabase()) see:
http://www.playframework.org/documentation/2.0/ScalaTest
OutOfMemory errors: However, running a sizeable test fixture a few times on my machine caused OutOfMemory errors. This seems to be because the default implementation of the inMemoryDatabase() function creates a new randomly named database and doesn't clean up the old ones between test runs. This isn't necessary if you've written your evolution teardown scripts correctly, because the database will be emptied out and refilled between each test. So we overrode this behaviour to use the same database and the memory issues disappeared.
DB Dialect: Another issue is that our production database is MySQL which has a number of incompatibilities with H2DB. H2DB has compatibility modes for a number of dbs, which should reduce the number of problems you have:
http://www.h2database.com/html/features.html#compatibility
Putting this all together makes it a little unwieldy to add before each test, so I extracted it into a function:
def memDB[T](code: =>T) =
running( FakeApplication( additionalConfiguration = Map(
"db.default.driver" -> "org.h2.Driver",
"db.default.url" -> "jdbc:h2:mem:test;MODE=MySQL"
) ) )(code)
You can then use it like so (specs example):
"My app" should {
"integrate nicely" in memDB {
.....
}
}
Every test will start a fake application, run your fixture setup evolutions script, run the test, then tear it all down again. Good luck!
Why not use the java example in Scala? That exact code should also work without modifications in Scala...
I have an assignment to code several methods in Scala. The methods will be encapsulated in an object that has no main method. The professor gave us a JAR file that contains an interface (my object implements this interface) as well as a sort of pseudo test object that performs various assert statements against each of my functions. This object also does not contain a main method.
Now in Intellij I simply had to declare the dependency on the JAR in the classpath, and it runs fine. Eclipse is giving me trouble though because when I go to define a Scala application run configuration it specifically asks me to name the class that contains a main method, and there is no main method.
I am assuming that I might be choosing the wrong project type for this type of set up, but I am inexperienced with this and I would appreciate any advice you might have for running something like this in eclipse.
Thanks.
I would either:
just write an object with a main method which calls the test object, or
start a Scala interpreter in your project (from context menu, under Scala).
Preferring the first approach, because it's faster to repeat tests after a modification.