Allow libs for test to be discovered via the classpath as well as via system properties.

This has been implemented to suppprt running tests via the maven surefire plugin, but is
a general-purpose mechanism.


git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/logging/trunk@427394 13f79535-47bb-0310-9956-ffa450edef68

src/test/org/apache/commons/logging/PathableClassLoader.java

@@ -197,22 +197,66 @@ public class PathableClassLoader extends URLClassLoader {
      * classes. 
      */
     public void addLogicalLib(String logicalLib) {
+        // first, check the system properties
         String filename = System.getProperty(logicalLib);
-        if (filename == null) {
-            throw new UnknownError(
-                "Logical lib [" + logicalLib + "] is not defined"
-                + " as a System property.");
-        }
-
+        if (filename != null) {
             try {
-            URL url = new File(filename).toURL();
-            addURL(url);
+                URL libUrl = new File(filename).toURL();
+                addURL(libUrl);
+                return;
             } catch(java.net.MalformedURLException e) {
                 throw new UnknownError(
                     "Invalid file [" + filename + "] for logical lib [" + logicalLib + "]");
             }
         }
 
+        // now check the classpath for a similar-named lib
+        URL libUrl = libFromClasspath(logicalLib);
+        if (libUrl != null) {
+            addURL(libUrl);
+            return;
+        }
+
+        // lib not found
+        throw new UnknownError(
+            "Logical lib [" + logicalLib + "] is not defined"
+            + " as a System property.");
+    }
+
+    private URL libFromClasspath(String logicalLib) {
+        ClassLoader cl = this.getClass().getClassLoader();
+        if (cl instanceof URLClassLoader == false) {
+            return null;
+        }
+        
+        URLClassLoader ucl = (URLClassLoader) cl;
+        URL[] path = ucl.getURLs();
+        for(int i=0; i<path.length; ++i) {
+            URL u = path[i];
+            
+            // extract the filename bit on the end of the url
+            String filename = u.toString();
+            if (!filename.endsWith(".jar")) {
+                // not a jarfile, ignore it
+                continue;
+            }
+
+            int lastSlash = filename.lastIndexOf('/');
+            if (lastSlash >= 0) {
+                filename = filename.substring(lastSlash+1);
+            }
+            
+            if (filename.startsWith(logicalLib)) {
+                System.out.println("found lib " + logicalLib + " at url " + u);
+                return u;
+            } else {
+                System.out.println("lib " + logicalLib + " does not match [" + filename + "] at url " + u);
+            }
+        }
+        
+        return null;
+        
+    }
     /**
      * Override ClassLoader method.
      * <p>