Add unit tests for glassfish 4.1 instrumentation

dd-java-agent/instrumentation/glassfish-4.1/src/main/java/datadog/trace/instrumentation/glassfish4/GlassfishInstrumentation.java

@@ -46,7 +46,7 @@ public final class GlassfishInstrumentation extends Instrumenter.Default {
   @Override
   public Map<? extends ElementMatcher<? super MethodDescription>, String> transformers() {
     return singletonMap(
-        isMethod().and(named("addToBlackList")).and(takesArguments(0)),
+        isMethod().and(named("addToBlackList")).and(takesArguments(1)),
         AvoidGlassFishBlacklistAdvice.class.getName());
   }
 

dd-java-agent/instrumentation/glassfish-4.1/src/test/java/datadog/trace/instrumentation/glassfish4/GlassfishInstrumentationTest.groovy

@@ -0,0 +1,34 @@
+package datadog.trace.instrumentation.glassfish4
+
+import datadog.trace.agent.test.AgentTestRunner
+import datadog.trace.agent.tooling.Constants
+import net.bytebuddy.matcher.NameMatcher
+
+class GlassfishInstrumentationTest extends AgentTestRunner {
+
+  def "test type matches the correct class loader"() {
+    setup:
+    def matchingType = new GlassfishInstrumentation().typeMatcher()
+
+    expect:
+    matchingType instanceof NameMatcher
+    matchingType.toString() == 'name(equals(com.sun.enterprise.v3.server.APIClassLoaderServiceImpl$APIClassLoader))'
+  }
+
+  def "test correct classes are added to the helpers"() {
+    setup:
+    def helpers = new GlassfishInstrumentation().helperClassNames()
+
+    expect:
+    Constants.class.getName() in helpers
+  }
+
+  def "test the advice is registered for the 'addToBlackList' method"() {
+    setup:
+    def transformers = new GlassfishInstrumentation().transformers()
+    def transformer = transformers.entrySet()[0]
+
+    expect:
+    transformer.key.toString() == '((isMethod() and name(equals(addToBlackList))) and hasParameter(ofSize(1)))'
+  }
+}