[Junit-devel] Strange JUnit interaction behaviour?

[Renouf, T. (Canopy) <Tim...@ch...>]

Hi all, 

I was trying to use JUnit to test an SAP JCO wrapper I had written. I began
to notice a problem with re-running the test from the JUnit GUI. I could run
the test successfully the first time, but the second run would error with...

java.lang.ExceptionInInitializerError: JCO.classInitialize(): Could not load
middleware layer 'com.sap.mw.jco.rfc.MiddlewareRFC' 

Native Library C:\Dev\externals\sapjco-ntintel-2.0.8\sapjcorfc.dll already
loaded in another classloader 
at com.sap.mw.jco.JCO.(Unknown Source) 
at SAPTest.testSAP(SAPTest.java:29) 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39
) 
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl
.java:25) 

...so I wrote a simplifed JUnit test... 

import com.sap.mw.jco.JCO; 
import junit.framework.TestCase; 

public class SAPTest extends TestCase { 
        private String client = "750"; 
        private String lang = "en"; 
        private String host = "xyz"; 
        private String sysnr = "03"; 

        private String userid = "fred"; 
        private String password = "super111"; 

        public void testSAP() { 
                // Get a client and connect 
                JCO.Client jclient = JCO.createClient(client, userid,
password, lang, host, sysnr); 
        } 
} 

...to check it and it still occurs. I'm starting to think this has something
to do with how JUnit use class loaders. Any ideas?

I guess I'm off to start trolling through the JUnit source. :-) 

Thanks, 

Tim. 


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