chore: improves error message for when dispatchers are empty accordingly to the agent.

agent-providers/span/src/main/java/com/expedia/www/haystack/agent/core/BaseAgent.java

@@ -4,6 +4,7 @@
 import com.expedia.www.haystack.agent.span.enricher.Enricher;
 import com.google.common.annotations.VisibleForTesting;
 import com.typesafe.config.Config;
+import org.apache.commons.lang3.StringUtils;
 import org.apache.commons.lang3.Validate;
 import org.slf4j.Logger;
 
@@ -53,7 +54,11 @@ public List<Dispatcher> loadAndInitializeDispatchers(final Config config, ClassL
                     });
         }
 
-        Validate.notEmpty(dispatchers, "Span agent dispatchers can't be an empty set");
+        Validate.notEmpty(
+                dispatchers,
+                "%s agent dispatchers can't be an empty set",
+                StringUtils.capitalize(getName())
+        );
 
         return dispatchers;
     }
@@ -66,7 +71,7 @@ public List<Enricher> loadSpanEnrichers(final Config config) {
                     .map(clazz -> {
                         try {
                             final Class c = Class.forName(clazz);
-                            logger.info("Initializing the span enricher with class name '{}'", clazz);
+                            logger.info("Initializing the {} enricher with class name '{}'", getName(), clazz);
                             return (Enricher) c.newInstance();
                         } catch (Exception e) {
                             logger.error("Fail to initialize the enricher with clazz name {}", clazz, e);

agent-providers/span/src/test/scala/com/expedia/www/haystack/agent/pitchfork/spi/PitchforkAgentSpec.scala

@@ -0,0 +1,117 @@
+/*
+ *  Copyright 2017 Expedia, Inc.
+ *
+ *     Licensed under the Apache License, Version 2.0 (the "License");
+ *     you may not use this file except in compliance with the License.
+ *     You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *     Unless required by applicable law or agreed to in writing, software
+ *     distributed under the License is distributed on an "AS IS" BASIS,
+ *     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *     See the License for the specific language governing permissions and
+ *     limitations under the License.
+ *
+ */
+
+
+package com.expedia.www.haystack.agent.pitchfork.spi
+
+import java.io.IOException
+import java.net.URL
+import java.util
+
+import com.expedia.open.tracing.Span
+import com.expedia.www.haystack.agent.span.enricher.Enricher
+import com.typesafe.config.ConfigFactory
+import org.scalatest.easymock.EasyMockSugar
+import org.scalatest.{FunSpec, Matchers}
+
+class DummyEnricher extends Enricher {
+  override def apply(span: Span.Builder): Unit = ()
+}
+
+class PitchforkAgentSpec extends FunSpec with Matchers with EasyMockSugar {
+
+  private val dispatcherLoadFile = "META-INF/services/com.expedia.www.haystack.agent.core.Dispatcher"
+
+  describe("Pitchfork Agent") {
+    it("should return the 'pitchfork' as agent name") {
+      new PitchforkAgent().getName shouldEqual "pitchfork"
+    }
+
+    it("should load the dispatchers from the config") {
+      val agent = new PitchforkAgent()
+      val cfg = ConfigFactory.parseString(
+        """
+          |    k1 = "v1"
+          |    port = 8080
+          |
+          |    dispatchers {
+          |      test-dispatcher {
+          |        queueName = "myqueue"
+          |      }
+          |    }
+        """.stripMargin)
+
+      val cl = new ReplacingClassLoader(getClass.getClassLoader, dispatcherLoadFile, "dispatcherProvider.txt")
+      val dispatchers = agent.loadAndInitializeDispatchers(cfg, cl, "spans")
+      dispatchers.size() shouldBe 1
+      dispatchers.get(0).close()
+    }
+
+    it("initialization should fail if no dispatchers exist") {
+      val agent = new PitchforkAgent()
+      val cfg = ConfigFactory.parseString(
+        """
+          |    k1 = "v1"
+          |    port = 8080
+          |
+          |    dispatchers {
+          |      test-dispatcher {
+          |        queueName = "myqueue"
+          |      }
+          |    }
+        """.stripMargin)
+
+      val caught = intercept[Exception] {
+        agent.loadAndInitializeDispatchers(cfg, getClass.getClassLoader, "spans")
+      }
+
+      caught.getMessage shouldEqual "Pitchfork agent dispatchers can't be an empty set"
+    }
+
+    it ("should load enrichers") {
+      val agent = new PitchforkAgent()
+      val cfg = ConfigFactory.parseString(
+        """
+          |    k1 = "v1"
+          |    port = 8080
+          |
+          |    enrichers = [
+          |       "com.expedia.www.haystack.agent.span.spi.DummyEnricher"
+          |    ]
+        """.stripMargin)
+      val enrichers = agent.loadSpanEnrichers(cfg)
+      enrichers.size() shouldBe 1
+    }
+  }
+
+  class ReplacingClassLoader(val parent: ClassLoader, val resource: String, val replacement: String) extends ClassLoader(parent) {
+    override def getResource(name: String): URL = {
+      if (resource == name) {
+        return getParent.getResource(replacement)
+      }
+      super.getResource(name)
+    }
+
+    @throws[IOException]
+    override def getResources(name: String): util.Enumeration[URL] = {
+      if (resource == name) {
+        return getParent.getResources(replacement)
+      }
+      super.getResources(name)
+    }
+  }
+}

agent-providers/span/src/test/scala/com/expedia/www/haystack/agent/span/spi/SpanAgentSpec.scala

@@ -133,7 +133,7 @@ class SpanAgentSpec extends FunSpec with Matchers with EasyMockSugar {
         agent.loadAndInitializeDispatchers(cfg, getClass.getClassLoader, "spans")
       }
 
-      caught.getMessage shouldEqual "Span agent dispatchers can't be an empty set"
+      caught.getMessage shouldEqual "Spans agent dispatchers can't be an empty set"
     }
 
     it ("should load enrichers") {