LOGBACK-833 - unit test improvements to check that a local timestamp …

…property really was set

logback-classic/src/test/input/joran/timestamp-local.xml

@@ -1,4 +1,7 @@
 <configuration>
   <timestamp key="testTimestamp" datePattern="yyyy-MM"/>
+  <property scope="system"  
+  	name="ch.qos.logback.classic.joran.JoranConfiguratorTest.timestampLocal" 
+  	value="today is ${testTimestamp}"/>
 </configuration>
 

logback-classic/src/test/java/ch/qos/logback/classic/joran/JoranConfiguratorTest.java

@@ -15,6 +15,8 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.text.SimpleDateFormat;
+import java.util.Date;
 import java.util.concurrent.TimeUnit;
 
 import ch.qos.logback.classic.jul.JULHelper;
@@ -326,13 +328,27 @@ public void timestamp() throws JoranException, IOException,
   @Test
   public void timestampLocal() throws JoranException, IOException,
           InterruptedException {
+
+	String sysProp = "ch.qos.logback.classic.joran.JoranConfiguratorTest.timestampLocal";
+	System.setProperty(sysProp, "");
 
     String configFileAsStr = ClassicTestConstants.JORAN_INPUT_PREFIX
             + "timestamp-local.xml";
     configure(configFileAsStr);
 
+	// It's hard to test the local variable has been set, as it's not
+	// visible from here. But instead we test that it's not set in the
+	// context. And check that a system property has been replaced with the
+	// contents of the local variable
+
     String r = loggerContext.getProperty("testTimestamp");
     assertNull(r);
+
+    String exprected = "today is " + new SimpleDateFormat("yyyy-MM").format(new Date());
+    String sysPropValue = System.getProperty(sysProp);
+    assertEquals(exprected, sysPropValue);
+
+
   }
 
   @Test