Fix #204: High memory usage of Metamorph tests

The metamorph test framework loads all test definitions into memory
prior to running the tests. For each test definition the Metamorph
script under test is instantiated. If there are many test cases this can
consume a lot of memory (in particular if the script is large).

This is changed so that the Metamorph module is created in the `run`
function of `TestCase` and stored in a local variable.

Author: cboehme

src/main/java/org/culturegraph/mf/test/TestCase.java

@@ -51,20 +51,13 @@ public final class TestCase {
 	private static final String STRICT_KEY_ORDER_ATTR = "strict-key-order";
 	private static final String STRICT_VALUE_ORDER_ATTR = "strict-value-order";
 
-
 	private static final String MIME_METAMORPH = "text/x-metamorph+xml";
 	private static final String MIME_JAVACLASS = "application/java";
 
 	private final Element config;
 
-	private final Reader inputReader;
-	private final StreamPipe<StreamReceiver> transformation;
-
-	@SuppressWarnings("unchecked")
 	public TestCase(final Element config) {
 		this.config = config;
-		inputReader = getReader(INPUT_TAG);
-		transformation = getTransformation();
 	}
 
 	public String getName() {
@@ -76,8 +69,11 @@ public boolean isIgnore() {
 	}
 
 	public void run() {
-
+		final Reader inputReader = getReader(INPUT_TAG);
+		@SuppressWarnings("unchecked")
+		final StreamPipe<StreamReceiver>transformation = getTransformation();
 		final EventList resultStream = new EventList();
+
 		if (transformation == null) {
 			inputReader.setReceiver(resultStream);
 		} else {