Reduce some test duplication by moving common classes to the main directory.

This allowed me to declare a test dependency on the servlet-3.0:testing directory.  (Test directories can't depend on other test directories.)

Still needed to copy over all the actual test classes because of how the test hierarchy is declared.

Author: tylerbenson

instrumentation/servlet/servlet-3.0/library/build.gradle.kts

@@ -5,6 +5,8 @@ plugins {
 dependencies {
   compileOnly("javax.servlet:javax.servlet-api:3.0.1")
 
+  testImplementation(project(":instrumentation:servlet:servlet-3.0:testing"))
+
   testLibrary("org.eclipse.jetty:jetty-server:8.0.0.v20110901")
   testLibrary("org.eclipse.jetty:jetty-servlet:8.0.0.v20110901")
   testLibrary("org.apache.tomcat.embed:tomcat-embed-core:8.0.41")

instrumentation/servlet/servlet-3.0/library/src/test/java/io/opentelemetry/instrumentation/servlet/v3_0/AbstractServlet3LibraryTest.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.servlet.v3_0;
+
+
+import io.opentelemetry.instrumentation.api.internal.HttpConstants;
+import io.opentelemetry.instrumentation.servlet.v3_0.copied.HttpServerResponseCustomizerHolder;
+import io.opentelemetry.instrumentation.testing.junit.http.HttpServerTestOptions;
+import io.opentelemetry.instrumentation.testing.junit.http.ServerEndpoint;
+import io.opentelemetry.javaagent.instrumentation.servlet.v3_0.AbstractServlet3Test;
+
+public abstract class AbstractServlet3LibraryTest<SERVER, CONTEXT>
+    extends AbstractServlet3Test<SERVER, CONTEXT> {
+
+  @Override
+  protected void configure(HttpServerTestOptions options) {
+    super.configure(options);
+    options.setTestCaptureRequestParameters(false); // Requires AgentConfig.
+    options.setTestCaptureHttpHeaders(false); // Requires AgentConfig.
+    options.disableTestNonStandardHttpMethod(); // test doesn't use route mapping correctly.
+    options.setTestException(false); // filters don't have visibility into exception handling above.
+    HttpServerResponseCustomizerHolder.setCustomizer(new TestAgentHttpResponseCustomizer());
+    options.setHasResponseCustomizer(e -> true);
+  }
+
+  @Override
+  public String expectedHttpRoute(ServerEndpoint endpoint, String method) {
+    // no need to compute route if we're not expecting it
+    if (!hasHttpRouteAttribute(endpoint)) {
+      return null;
+    }
+
+    if (method.equals(HttpConstants._OTHER)) {
+      return getContextPath() + endpoint.getPath();
+    }
+
+    // NOTE: Primary difference from javaagent servlet instrumentation!
+    // Since just we're working with a filter, we can't actually get the proper servlet path.
+    return getContextPath() + "/*";
+  }
+
+  @Override
+  protected void snippetInjectionWithServletOutputStream() {
+    // override
+  }
+
+  @Override
+  protected void snippetInjectionWithPrintWriter() {
+    // override
+  }
+}