Extract base test class and move Config class changes there.

dd-java-agent/agent-tooling/src/test/groovy/datadog/trace/agent/decorator/BaseDecoratorTest.groovy

@@ -1,21 +1,16 @@
 package datadog.trace.agent.decorator
 
-
 import datadog.trace.agent.test.utils.ConfigUtils
 import datadog.trace.api.DDTags
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.Scope
 import io.opentracing.Span
 import io.opentracing.tag.Tags
 import spock.lang.Shared
-import spock.lang.Specification
 
 import static io.opentracing.log.Fields.ERROR_OBJECT
 
-class BaseDecoratorTest extends Specification {
+class BaseDecoratorTest extends DDSpecification {
-
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
 
   @Shared
   def decorator = newDecorator()

dd-java-agent/agent-tooling/src/test/groovy/datadog/trace/agent/test/ClassLoaderMatcherTest.groovy

@@ -2,9 +2,9 @@ package datadog.trace.agent.test
 
 import datadog.trace.agent.tooling.ClassLoaderMatcher
 import datadog.trace.bootstrap.DatadogClassLoader
-import spock.lang.Specification
+import datadog.trace.util.test.DDSpecification
 
-class ClassLoaderMatcherTest extends Specification {
+class ClassLoaderMatcherTest extends DDSpecification {
 
   def "skip non-delegating classloader"() {
     setup:

dd-java-agent/agent-tooling/src/test/groovy/datadog/trace/agent/test/DefaultInstrumenterTest.groovy

@@ -2,18 +2,15 @@ package datadog.trace.agent.test
 
 import datadog.trace.agent.test.utils.ConfigUtils
 import datadog.trace.agent.tooling.Instrumenter
+import datadog.trace.util.test.DDSpecification
 import net.bytebuddy.agent.builder.AgentBuilder
 import net.bytebuddy.description.type.TypeDescription
 import net.bytebuddy.matcher.ElementMatcher
 import org.junit.Rule
 import org.junit.contrib.java.lang.system.EnvironmentVariables
 import org.junit.contrib.java.lang.system.RestoreSystemProperties
-import spock.lang.Specification
 
-class DefaultInstrumenterTest extends Specification {
+class DefaultInstrumenterTest extends DDSpecification {
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
 
   @Rule
   public final RestoreSystemProperties restoreSystemProperties = new RestoreSystemProperties()

dd-java-agent/agent-tooling/src/test/groovy/datadog/trace/agent/test/ExceptionHandlerTest.groovy

@@ -5,18 +5,18 @@ import ch.qos.logback.classic.Logger
 import ch.qos.logback.core.read.ListAppender
 import datadog.trace.agent.tooling.ExceptionHandlers
 import datadog.trace.bootstrap.ExceptionLogger
+import datadog.trace.util.test.DDSpecification
 import net.bytebuddy.agent.ByteBuddyAgent
 import net.bytebuddy.agent.builder.AgentBuilder
 import net.bytebuddy.agent.builder.ResettableClassFileTransformer
 import net.bytebuddy.dynamic.ClassFileLocator
 import org.slf4j.LoggerFactory
 import spock.lang.Shared
-import spock.lang.Specification
 
 import static net.bytebuddy.matcher.ElementMatchers.isMethod
 import static net.bytebuddy.matcher.ElementMatchers.named
 
-class ExceptionHandlerTest extends Specification {
+class ExceptionHandlerTest extends DDSpecification {
   @Shared
   ListAppender testAppender = new ListAppender()
   @Shared

dd-java-agent/agent-tooling/src/test/groovy/datadog/trace/agent/test/HelperInjectionTest.groovy

@@ -1,14 +1,14 @@
 package datadog.trace.agent.test
 
-import datadog.trace.agent.test.utils.ConfigUtils
+
 import datadog.trace.agent.tooling.AgentInstaller
 import datadog.trace.agent.tooling.HelperInjector
 import datadog.trace.agent.tooling.Utils
+import datadog.trace.util.test.DDSpecification
 import net.bytebuddy.agent.ByteBuddyAgent
 import net.bytebuddy.description.type.TypeDescription
 import net.bytebuddy.dynamic.ClassFileLocator
 import net.bytebuddy.dynamic.loading.ClassInjector
-import spock.lang.Specification
 import spock.lang.Timeout
 
 import java.lang.ref.WeakReference
@@ -18,10 +18,7 @@ import static datadog.trace.agent.test.utils.ClasspathUtils.isClassLoaded
 import static datadog.trace.agent.tooling.ClassLoaderMatcher.BOOTSTRAP_CLASSLOADER
 import static datadog.trace.util.gc.GCUtils.awaitGC
 
-class HelperInjectionTest extends Specification {
+class HelperInjectionTest extends DDSpecification {
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
 
   @Timeout(10)
   def "helpers injected to non-delegating classloader"() {

dd-java-agent/agent-tooling/src/test/groovy/datadog/trace/agent/test/ResourceLocatingTest.groovy

@@ -1,12 +1,13 @@
 package datadog.trace.agent.test
 
 import datadog.trace.agent.tooling.DDLocationStrategy
-import java.util.concurrent.atomic.AtomicReference
+import datadog.trace.util.test.DDSpecification
 import net.bytebuddy.agent.builder.AgentBuilder
 import spock.lang.Shared
-import spock.lang.Specification
 
-class ResourceLocatingTest extends Specification {
+import java.util.concurrent.atomic.AtomicReference
+
+class ResourceLocatingTest extends DDSpecification {
   @Shared
   def lastLookup = new AtomicReference<String>()
   @Shared

dd-java-agent/agent-tooling/src/test/groovy/datadog/trace/agent/tooling/CleanerTest.groovy

@@ -1,7 +1,7 @@
 package datadog.trace.agent.tooling
 
 import datadog.trace.util.gc.GCUtils
-import spock.lang.Specification
+import datadog.trace.util.test.DDSpecification
 import spock.lang.Subject
 
 import java.lang.ref.WeakReference
@@ -10,7 +10,7 @@ import java.util.concurrent.atomic.AtomicInteger
 
 import static java.util.concurrent.TimeUnit.MILLISECONDS
 
-class CleanerTest extends Specification {
+class CleanerTest extends DDSpecification {
 
   @Subject
   def cleaner = new Cleaner()

dd-java-agent/agent-tooling/src/test/groovy/datadog/trace/agent/tooling/EvictingCacheProviderTest.groovy

@@ -1,9 +1,9 @@
 package datadog.trace.agent.tooling
 
 import datadog.trace.util.gc.GCUtils
+import datadog.trace.util.test.DDSpecification
 import net.bytebuddy.description.type.TypeDescription
 import net.bytebuddy.pool.TypePool
-import spock.lang.Specification
 import spock.lang.Timeout
 
 import java.lang.ref.WeakReference
@@ -13,7 +13,7 @@ import java.util.concurrent.atomic.AtomicReference
 import static datadog.trace.agent.tooling.AgentTooling.CLEANER
 
 @Timeout(5)
-class EvictingCacheProviderTest extends Specification {
+class EvictingCacheProviderTest extends DDSpecification {
 
   def "test provider"() {
     setup:

dd-java-agent/agent-tooling/src/test/groovy/datadog/trace/agent/tooling/UtilsTest.groovy

@@ -1,9 +1,8 @@
 package datadog.trace.agent.tooling
 
-import spock.lang.Specification
+import datadog.trace.util.test.DDSpecification
 
-
+class UtilsTest extends DDSpecification {
-class UtilsTest extends Specification {
 
   def "getStackTraceAsString() returns the stack trace as a single new line separated string"() {
     setup:

dd-java-agent/agent-tooling/src/test/groovy/datadog/trace/agent/tooling/WeakConcurrentSupplierTest.groovy

@@ -2,9 +2,9 @@ package datadog.trace.agent.tooling
 
 import datadog.trace.bootstrap.WeakMap
 import datadog.trace.util.gc.GCUtils
+import datadog.trace.util.test.DDSpecification
 import spock.lang.Retry
 import spock.lang.Shared
-import spock.lang.Specification
 
 import java.lang.ref.WeakReference
 import java.util.concurrent.TimeUnit
@@ -13,7 +13,7 @@ import static datadog.trace.agent.tooling.AgentTooling.CLEANER
 
 @Retry
 // These tests fail sometimes in CI.
-class WeakConcurrentSupplierTest extends Specification {
+class WeakConcurrentSupplierTest extends DDSpecification {
   @Shared
   def weakConcurrentSupplier = new WeakMapSuppliers.WeakConcurrent(CLEANER)
   @Shared

dd-java-agent/instrumentation/jdbc/src/test/groovy/JDBCConnectionUrlParserTest.groovy

@@ -1,10 +1,10 @@
 import datadog.trace.instrumentation.jdbc.DBInfo
+import datadog.trace.util.test.DDSpecification
 import spock.lang.Shared
-import spock.lang.Specification
 
 import static datadog.trace.instrumentation.jdbc.JDBCConnectionUrlParser.parse
 
-class JDBCConnectionUrlParserTest extends Specification {
+class JDBCConnectionUrlParserTest extends DDSpecification {
 
   @Shared
   def stdProps = {

dd-java-agent/instrumentation/twilio/twilio.gradle

@@ -20,7 +20,6 @@ dependencies {
   testCompile group: 'com.twilio.sdk', name: 'twilio', version: '0.0.1'
   testCompile project(':dd-java-agent:instrumentation:apache-httpclient-4')
   testCompile project(':dd-java-agent:instrumentation:java-concurrent')
-  testCompile group: 'org.objenesis', name: 'objenesis', version: '2.6' // Last version to support Java7
   testCompile group: 'nl.jqno.equalsverifier', name: 'equalsverifier', version: '2.5.2' // Last version to support Java7
 
   latestDepTestCompile group: 'com.twilio.sdk', name: 'twilio', version: '+'

dd-java-agent/testing/src/main/groovy/datadog/trace/agent/test/AgentTestRunner.java

@@ -7,13 +7,13 @@ import datadog.opentracing.DDSpan;
 import datadog.opentracing.DDTracer;
 import datadog.opentracing.PendingTrace;
 import datadog.trace.agent.test.asserts.ListWriterAssert;
-import datadog.trace.agent.test.utils.ConfigUtils;
 import datadog.trace.agent.test.utils.GlobalTracerUtils;
 import datadog.trace.agent.tooling.AgentInstaller;
 import datadog.trace.agent.tooling.Instrumenter;
 import datadog.trace.api.GlobalTracer;
 import datadog.trace.common.writer.ListWriter;
 import datadog.trace.common.writer.Writer;
+import datadog.trace.util.test.DDSpecification;
 import groovy.lang.Closure;
 import groovy.lang.DelegatesTo;
 import groovy.transform.stc.ClosureParams;
@@ -41,7 +41,6 @@ import org.junit.BeforeClass;
 import org.junit.runner.RunWith;
 import org.slf4j.LoggerFactory;
 import org.spockframework.runtime.model.SpecMetadata;
-import spock.lang.Specification;
 
 /**
  * A spock test runner which automatically applies instrumentation and exposes a global trace
@@ -61,7 +60,7 @@ import spock.lang.Specification;
 @RunWith(SpockRunner.class)
 @SpecMetadata(filename = "AgentTestRunner.java", line = 0)
 @Slf4j
-public abstract class AgentTestRunner extends Specification {
+public abstract class AgentTestRunner extends DDSpecification {
   private static final long TIMEOUT_MILLIS = 10 * 1000;
   /**
    * For test runs, agent's global tracer will report to this list writer.
@@ -88,8 +87,6 @@ public abstract class AgentTestRunner extends Specification {
     ((Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME)).setLevel(Level.WARN);
     ((Logger) LoggerFactory.getLogger("datadog")).setLevel(Level.DEBUG);
 
-    ConfigUtils.makeConfigInstanceModifiable();
-
     TEST_WRITER =
         new ListWriter() {
           @Override

dd-java-agent/testing/src/main/groovy/datadog/trace/agent/test/utils/ConfigUtils.groovy

@@ -2,44 +2,32 @@ package datadog.trace.agent.test.utils
 
 import datadog.trace.api.Config
 import lombok.SneakyThrows
-import net.bytebuddy.agent.ByteBuddyAgent
-import net.bytebuddy.agent.builder.AgentBuilder
-import net.bytebuddy.dynamic.ClassFileLocator
-import net.bytebuddy.dynamic.Transformer
 
 import java.lang.reflect.Modifier
 import java.util.concurrent.Callable
 
-import static net.bytebuddy.description.modifier.FieldManifestation.VOLATILE
-import static net.bytebuddy.description.modifier.Ownership.STATIC
-import static net.bytebuddy.description.modifier.Visibility.PUBLIC
-import static net.bytebuddy.matcher.ElementMatchers.named
-import static net.bytebuddy.matcher.ElementMatchers.none
-
 class ConfigUtils {
-  private static class ConfigInstance {
+
-    // Wrapped in a static class to lazy load.
+  static final CONFIG_INSTANCE_FIELD = Config.getDeclaredField("INSTANCE")
-    static final FIELD = Config.getDeclaredField("INSTANCE")
   static final RUNTIME_ID_FIELD = Config.getDeclaredField("runtimeId")
-  }
 
   @SneakyThrows
   synchronized static <T extends Object> Object withConfigOverride(final String name, final String value, final Callable<T> r) {
-    // Ensure the class was retransformed properly in AgentTestRunner.makeConfigInstanceModifiable()
+    // Ensure the class was retransformed properly in DDSpecification.makeConfigInstanceModifiable()
-    assert Modifier.isPublic(ConfigInstance.FIELD.getModifiers())
+    assert Modifier.isPublic(CONFIG_INSTANCE_FIELD.getModifiers())
-    assert Modifier.isStatic(ConfigInstance.FIELD.getModifiers())
+    assert Modifier.isStatic(CONFIG_INSTANCE_FIELD.getModifiers())
-    assert Modifier.isVolatile(ConfigInstance.FIELD.getModifiers())
+    assert Modifier.isVolatile(CONFIG_INSTANCE_FIELD.getModifiers())
-    assert !Modifier.isFinal(ConfigInstance.FIELD.getModifiers())
+    assert !Modifier.isFinal(CONFIG_INSTANCE_FIELD.getModifiers())
 
     def existingConfig = Config.get()
     Properties properties = new Properties()
     properties.put(name, value)
-    ConfigInstance.FIELD.set(null, new Config(properties, existingConfig))
+    CONFIG_INSTANCE_FIELD.set(null, new Config(properties, existingConfig))
     assert Config.get() != existingConfig
     try {
       return r.call()
     } finally {
-      ConfigInstance.FIELD.set(null, existingConfig)
+      CONFIG_INSTANCE_FIELD.set(null, existingConfig)
     }
   }
 
@@ -50,7 +38,6 @@ class ConfigUtils {
    * @return
    */
   static updateConfig(final Callable r) {
-    makeConfigInstanceModifiable()
     r.call()
     resetConfig()
   }
@@ -59,71 +46,22 @@ class ConfigUtils {
    * Reset the global configuration. Please note that Runtime ID is preserved to the pre-existing value.
    */
   static void resetConfig() {
-    // Ensure the class was re-transformed properly in AgentTestRunner.makeConfigInstanceModifiable()
+    // Ensure the class was re-transformed properly in DDSpecification.makeConfigInstanceModifiable()
-    assert Modifier.isPublic(ConfigInstance.FIELD.getModifiers())
+    assert Modifier.isPublic(CONFIG_INSTANCE_FIELD.getModifiers())
-    assert Modifier.isStatic(ConfigInstance.FIELD.getModifiers())
+    assert Modifier.isStatic(CONFIG_INSTANCE_FIELD.getModifiers())
-    assert Modifier.isVolatile(ConfigInstance.FIELD.getModifiers())
+    assert Modifier.isVolatile(CONFIG_INSTANCE_FIELD.getModifiers())
-    assert !Modifier.isFinal(ConfigInstance.FIELD.getModifiers())
+    assert !Modifier.isFinal(CONFIG_INSTANCE_FIELD.getModifiers())
 
-    assert Modifier.isPublic(ConfigInstance.RUNTIME_ID_FIELD.getModifiers())
+    assert Modifier.isPublic(RUNTIME_ID_FIELD.getModifiers())
-    assert !Modifier.isStatic(ConfigInstance.RUNTIME_ID_FIELD.getModifiers())
+    assert !Modifier.isStatic(RUNTIME_ID_FIELD.getModifiers())
-    assert Modifier.isVolatile(ConfigInstance.RUNTIME_ID_FIELD.getModifiers())
+    assert Modifier.isVolatile(RUNTIME_ID_FIELD.getModifiers())
-    assert !Modifier.isFinal(ConfigInstance.RUNTIME_ID_FIELD.getModifiers())
+    assert !Modifier.isFinal(RUNTIME_ID_FIELD.getModifiers())
 
-    def previousConfig = ConfigInstance.FIELD.get(null)
+    def previousConfig = CONFIG_INSTANCE_FIELD.get(null)
     def newConfig = new Config()
-    ConfigInstance.FIELD.set(null, newConfig)
+    CONFIG_INSTANCE_FIELD.set(null, newConfig)
     if (previousConfig != null) {
-      ConfigInstance.RUNTIME_ID_FIELD.set(newConfig, ConfigInstance.RUNTIME_ID_FIELD.get(previousConfig))
+      RUNTIME_ID_FIELD.set(newConfig, RUNTIME_ID_FIELD.get(previousConfig))
     }
   }
-
-  // Keep track of config instance already made modifiable
-  private static isConfigInstanceModifiable = false
-
-  static void makeConfigInstanceModifiable() {
-    if (isConfigInstanceModifiable) {
-      return
-    }
-
-    def instrumentation = ByteBuddyAgent.install()
-    final transformer =
-      new AgentBuilder.Default()
-        .with(AgentBuilder.RedefinitionStrategy.RETRANSFORMATION)
-        .with(AgentBuilder.RedefinitionStrategy.Listener.ErrorEscalating.FAIL_FAST)
-        // Config is injected into the bootstrap, so we need to provide a locator.
-        .with(
-          new AgentBuilder.LocationStrategy.Simple(
-            ClassFileLocator.ForClassLoader.ofSystemLoader()))
-        .ignore(none()) // Allow transforming bootstrap classes
-        .type(named("datadog.trace.api.Config"))
-        .transform { builder, typeDescription, classLoader, module ->
-          builder
-            .field(named("INSTANCE"))
-            .transform(Transformer.ForField.withModifiers(PUBLIC, STATIC, VOLATILE))
-        }
-        // Making runtimeId modifiable so that it can be preserved when resetting config in tests
-        .transform { builder, typeDescription, classLoader, module ->
-          builder
-            .field(named("runtimeId"))
-            .transform(Transformer.ForField.withModifiers(PUBLIC, VOLATILE))
-        }
-        .installOn(instrumentation)
-    isConfigInstanceModifiable = true
-
-    final field = ConfigInstance.FIELD
-    assert Modifier.isPublic(field.getModifiers())
-    assert Modifier.isStatic(field.getModifiers())
-    assert Modifier.isVolatile(field.getModifiers())
-    assert !Modifier.isFinal(field.getModifiers())
-
-    final runtimeIdField = ConfigInstance.RUNTIME_ID_FIELD
-    assert Modifier.isPublic(runtimeIdField.getModifiers())
-    assert !Modifier.isStatic(ConfigInstance.RUNTIME_ID_FIELD.getModifiers())
-    assert Modifier.isVolatile(runtimeIdField.getModifiers())
-    assert !Modifier.isFinal(runtimeIdField.getModifiers())
-
-    // No longer needed (Unless class gets retransformed somehow).
-    instrumentation.removeTransformer(transformer)
-  }
 }

dd-java-agent/testing/testing.gradle

@@ -24,6 +24,7 @@ dependencies {
   compile group: 'org.eclipse.jetty', name: 'jetty-server', version: '8.0.0.v20110901'
 
   compile project(':dd-java-agent:agent-tooling')
+  compile project(':utils:test-utils')
 
   annotationProcessor deps.autoservice
   implementation deps.autoservice
@@ -31,6 +32,7 @@ dependencies {
   compile deps.groovy
 
   testCompile project(':utils:gc-utils')
+  testCompile project(':utils:test-utils')
   testCompile project(':dd-java-agent:instrumentation:trace-annotation')
 
   testCompile group: 'cglib', name: 'cglib', version: '3.2.5'

dd-trace-api/dd-trace-api.gradle

@@ -15,5 +15,5 @@ excludedClassesCoverage += [
 description = 'dd-trace-api'
 dependencies {
   compile deps.slf4j
-  testCompile deps.junit
+  testCompile project(':utils:test-utils')
 }

dd-trace-api/src/test/groovy/datadog/trace/api/ConfigTest.groovy

@@ -1,9 +1,9 @@
 package datadog.trace.api
 
+import datadog.trace.util.test.DDSpecification
 import org.junit.Rule
 import org.junit.contrib.java.lang.system.EnvironmentVariables
 import org.junit.contrib.java.lang.system.RestoreSystemProperties
-import spock.lang.Specification
 
 import static datadog.trace.api.Config.AGENT_HOST
 import static datadog.trace.api.Config.AGENT_PORT_LEGACY
@@ -41,7 +41,7 @@ import static datadog.trace.api.Config.TRACE_REPORT_HOSTNAME
 import static datadog.trace.api.Config.TRACE_RESOLVER_ENABLED
 import static datadog.trace.api.Config.WRITER_TYPE
 
-class ConfigTest extends Specification {
+class ConfigTest extends DDSpecification {
   @Rule
   public final RestoreSystemProperties restoreSystemProperties = new RestoreSystemProperties()
   @Rule

dd-trace-ot/dd-trace-ot.gradle

@@ -44,10 +44,7 @@ dependencies {
 
   testCompile project(":dd-java-agent:testing")
   testCompile project(':utils:gc-utils')
-  testCompile group: 'org.assertj', name: 'assertj-core', version: '2.9.+'
+//  testCompile group: 'cglib', name: 'cglib-nodep', version: '3.2.5'
-  testCompile group: 'org.mockito', name: 'mockito-core', version: '2.19.0'
-  testCompile group: 'org.objenesis', name: 'objenesis', version: '2.6' // Last version to support Java7
-  testCompile group: 'cglib', name: 'cglib-nodep', version: '3.2.5'
   testCompile group: 'com.github.stefanbirkner', name: 'system-rules', version: '1.17.1'
 
   traceAgentTestCompile deps.testcontainers

dd-trace-ot/src/test/groovy/datadog/opentracing/ContainerInfoTest.groovy

@@ -1,10 +1,9 @@
 package datadog.opentracing
 
-import spock.lang.Specification
+import datadog.trace.util.test.DDSpecification
 import spock.lang.Unroll
 
-
+class ContainerInfoTest extends DDSpecification {
-class ContainerInfoTest extends Specification {
 
   @Unroll
   def "CGroupInfo is parsed from individual lines"() {

dd-trace-ot/src/test/groovy/datadog/opentracing/DDSpanBuilderTest.groovy

@@ -2,24 +2,18 @@ package datadog.opentracing
 
 import datadog.opentracing.propagation.ExtractedContext
 import datadog.opentracing.propagation.TagContext
-import datadog.trace.agent.test.utils.ConfigUtils
 import datadog.trace.api.Config
 import datadog.trace.api.DDTags
 import datadog.trace.api.sampling.PrioritySampling
 import datadog.trace.common.writer.ListWriter
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.Scope
 import io.opentracing.noop.NoopSpan
-import spock.lang.Specification
 
 import static datadog.opentracing.DDSpanContext.ORIGIN_KEY
 import static java.util.concurrent.TimeUnit.MILLISECONDS
-import static org.mockito.Mockito.mock
-import static org.mockito.Mockito.when
 
-class DDSpanBuilderTest extends Specification {
+class DDSpanBuilderTest extends DDSpecification {
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
 
   def writer = new ListWriter()
   def config = Config.get()
@@ -158,11 +152,12 @@ class DDSpanBuilderTest extends Specification {
     final String spanId = "1"
     final long expectedParentId = spanId
 
-    final DDSpanContext mockedContext = mock(DDSpanContext)
+    final DDSpanContext mockedContext = Mock()
-    when(mockedContext.getTraceId()).thenReturn(spanId)
+    1 * mockedContext.getTraceId() >> spanId
-    when(mockedContext.getSpanId()).thenReturn(spanId)
+    1 * mockedContext.getSpanId() >> spanId
-    when(mockedContext.getServiceName()).thenReturn("foo")
+    _ * mockedContext.getServiceName() >> "foo"
-    when(mockedContext.getTrace()).thenReturn(new PendingTrace(tracer, "1", [:]))
+    1 * mockedContext.getBaggageItems() >> [:]
+    1 * mockedContext.getTrace() >> new PendingTrace(tracer, "1", [:])
 
     final String expectedName = "fakeName"
 

dd-trace-ot/src/test/groovy/datadog/opentracing/DDSpanSerializationTest.groovy

@@ -2,20 +2,16 @@ package datadog.opentracing
 
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.collect.Maps
-import datadog.trace.agent.test.utils.ConfigUtils
 import datadog.trace.api.DDTags
 import datadog.trace.api.sampling.PrioritySampling
 import datadog.trace.common.writer.ListWriter
+import datadog.trace.util.test.DDSpecification
 import org.msgpack.core.MessagePack
 import org.msgpack.core.buffer.ArrayBufferInput
 import org.msgpack.jackson.dataformat.MessagePackFactory
 import org.msgpack.value.ValueType
-import spock.lang.Specification
 
-class DDSpanSerializationTest extends Specification {
+class DDSpanSerializationTest extends DDSpecification {
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
 
   def "serialize spans with sampling #samplingPriority"() throws Exception {
     setup:

dd-trace-ot/src/test/groovy/datadog/opentracing/DDSpanTest.groovy

@@ -1,26 +1,21 @@
 package datadog.opentracing
 
-
 import com.fasterxml.jackson.databind.ObjectMapper
 import datadog.opentracing.propagation.ExtractedContext
 import datadog.opentracing.propagation.TagContext
-import datadog.trace.agent.test.utils.ConfigUtils
 import datadog.trace.api.DDTags
 import datadog.trace.api.sampling.PrioritySampling
 import datadog.trace.common.sampling.RateByServiceSampler
 import datadog.trace.common.writer.ListWriter
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.SpanContext
 import spock.lang.Shared
-import spock.lang.Specification
 
 import java.util.concurrent.TimeUnit
 
 import static datadog.trace.api.Config.DEFAULT_SERVICE_NAME
 
-class DDSpanTest extends Specification {
+class DDSpanTest extends DDSpecification {
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
 
   def writer = new ListWriter()
   def sampler = new RateByServiceSampler()

dd-trace-ot/src/test/groovy/datadog/opentracing/PendingTraceTest.groovy

@@ -1,10 +1,10 @@
 package datadog.opentracing
 
-import datadog.trace.agent.test.utils.ConfigUtils
+
 import datadog.trace.api.Config
 import datadog.trace.common.writer.ListWriter
 import datadog.trace.util.gc.GCUtils
-import spock.lang.Specification
+import datadog.trace.util.test.DDSpecification
 import spock.lang.Subject
 import spock.lang.Timeout
 
@@ -14,10 +14,7 @@ import java.util.concurrent.atomic.AtomicInteger
 
 import static datadog.trace.api.Config.PARTIAL_FLUSH_MIN_SPANS
 
-class PendingTraceTest extends Specification {
+class PendingTraceTest extends DDSpecification {
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
 
   def traceCount = new AtomicInteger()
   def writer = new ListWriter() {

dd-trace-ot/src/test/groovy/datadog/opentracing/SpanFactory.groovy

@@ -1,13 +1,10 @@
 package datadog.opentracing
 
-import datadog.trace.agent.test.utils.ConfigUtils
+
 import datadog.trace.api.sampling.PrioritySampling
 import datadog.trace.common.writer.ListWriter
 
 class SpanFactory {
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
 
   static DDSpan newSpanOf(long timestampMicro, String threadName = Thread.currentThread().name) {
     def writer = new ListWriter()

dd-trace-ot/src/test/groovy/datadog/opentracing/TraceCorrelationTest.groovy

@@ -1,14 +1,11 @@
 package datadog.opentracing
 
-import datadog.trace.agent.test.utils.ConfigUtils
-import datadog.trace.common.writer.ListWriter
-import spock.lang.Shared
-import spock.lang.Specification
 
-class TraceCorrelationTest extends Specification {
+import datadog.trace.common.writer.ListWriter
-  static {
+import datadog.trace.util.test.DDSpecification
-    ConfigUtils.makeConfigInstanceModifiable()
+import spock.lang.Shared
-  }
+
+class TraceCorrelationTest extends DDSpecification {
 
   static final WRITER = new ListWriter()
 

dd-trace-ot/src/test/groovy/datadog/opentracing/TraceInterceptorTest.groovy

@@ -1,18 +1,15 @@
 package datadog.opentracing
 
-import datadog.trace.agent.test.utils.ConfigUtils
+
 import datadog.trace.api.GlobalTracer
 import datadog.trace.api.interceptor.MutableSpan
 import datadog.trace.api.interceptor.TraceInterceptor
 import datadog.trace.common.writer.ListWriter
-import spock.lang.Specification
+import datadog.trace.util.test.DDSpecification
 
 import java.util.concurrent.atomic.AtomicBoolean
 
-class TraceInterceptorTest extends Specification {
+class TraceInterceptorTest extends DDSpecification {
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
 
   def writer = new ListWriter()
   def tracer = new DDTracer(writer)

dd-trace-ot/src/test/groovy/datadog/opentracing/decorators/SpanDecoratorTest.groovy

@@ -9,17 +9,16 @@ import datadog.trace.api.DDSpanTypes
 import datadog.trace.api.DDTags
 import datadog.trace.common.sampling.AllSampler
 import datadog.trace.common.writer.LoggingWriter
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.tag.StringTag
 import io.opentracing.tag.Tags
-import spock.lang.Specification
 
 import static datadog.trace.api.Config.DEFAULT_SERVICE_NAME
 import static datadog.trace.api.DDTags.EVENT_SAMPLE_RATE
 import static java.util.Collections.emptyMap
 
-class SpanDecoratorTest extends Specification {
+class SpanDecoratorTest extends DDSpecification {
   static {
-    ConfigUtils.makeConfigInstanceModifiable()
     ConfigUtils.updateConfig {
       System.setProperty("dd.$Config.SPLIT_BY_TAGS", "sn.tag1,sn.tag2")
     }

dd-trace-ot/src/test/groovy/datadog/opentracing/decorators/URLAsResourceNameTest.groovy

@@ -3,17 +3,13 @@ package datadog.opentracing.decorators
 import datadog.opentracing.DDSpanContext
 import datadog.opentracing.DDTracer
 import datadog.opentracing.PendingTrace
-import datadog.trace.agent.test.utils.ConfigUtils
 import datadog.trace.api.sampling.PrioritySampling
 import datadog.trace.common.writer.ListWriter
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.tag.Tags
-import spock.lang.Specification
 import spock.lang.Subject
 
-class URLAsResourceNameTest extends Specification {
+class URLAsResourceNameTest extends DDSpecification {
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
 
   def writer = new ListWriter()
   def tracer = new DDTracer(writer)

dd-trace-ot/src/test/groovy/datadog/opentracing/propagation/B3HttpExtractorTest.groovy

@@ -1,16 +1,16 @@
 package datadog.opentracing.propagation
 
 import datadog.trace.api.sampling.PrioritySampling
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.SpanContext
 import io.opentracing.propagation.TextMapExtractAdapter
-import spock.lang.Specification
 
 import static datadog.opentracing.propagation.B3HttpCodec.SAMPLING_PRIORITY_KEY
 import static datadog.opentracing.propagation.B3HttpCodec.SPAN_ID_KEY
 import static datadog.opentracing.propagation.B3HttpCodec.TRACE_ID_KEY
 import static datadog.opentracing.propagation.HttpCodec.UINT64_MAX
 
-class B3HttpExtractorTest extends Specification {
+class B3HttpExtractorTest extends DDSpecification {
 
   HttpCodec.Extractor extractor = new B3HttpCodec.Extractor(["SOME_HEADER": "some-tag"])
 

dd-trace-ot/src/test/groovy/datadog/opentracing/propagation/B3HttpInjectorTest.groovy

@@ -5,15 +5,15 @@ import datadog.opentracing.DDTracer
 import datadog.opentracing.PendingTrace
 import datadog.trace.api.sampling.PrioritySampling
 import datadog.trace.common.writer.ListWriter
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.propagation.TextMapInjectAdapter
-import spock.lang.Specification
 
 import static datadog.opentracing.propagation.B3HttpCodec.SAMPLING_PRIORITY_KEY
 import static datadog.opentracing.propagation.B3HttpCodec.SPAN_ID_KEY
 import static datadog.opentracing.propagation.B3HttpCodec.TRACE_ID_KEY
 import static datadog.opentracing.propagation.HttpCodec.UINT64_MAX
 
-class B3HttpInjectorTest extends Specification {
+class B3HttpInjectorTest extends DDSpecification {
 
   HttpCodec.Injector injector = new B3HttpCodec.Injector()
 

dd-trace-ot/src/test/groovy/datadog/opentracing/propagation/DatadogHttpExtractorTest.groovy

@@ -1,9 +1,9 @@
 package datadog.opentracing.propagation
 
 import datadog.trace.api.sampling.PrioritySampling
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.SpanContext
 import io.opentracing.propagation.TextMapExtractAdapter
-import spock.lang.Specification
 
 import static datadog.opentracing.propagation.DatadogHttpCodec.ORIGIN_KEY
 import static datadog.opentracing.propagation.DatadogHttpCodec.OT_BAGGAGE_PREFIX
@@ -12,7 +12,7 @@ import static datadog.opentracing.propagation.DatadogHttpCodec.SPAN_ID_KEY
 import static datadog.opentracing.propagation.DatadogHttpCodec.TRACE_ID_KEY
 import static datadog.opentracing.propagation.HttpCodec.UINT64_MAX
 
-class DatadogHttpExtractorTest extends Specification {
+class DatadogHttpExtractorTest extends DDSpecification {
 
   HttpCodec.Extractor extractor = new DatadogHttpCodec.Extractor(["SOME_HEADER": "some-tag"])
 

dd-trace-ot/src/test/groovy/datadog/opentracing/propagation/DatadogHttpInjectorTest.groovy

@@ -5,8 +5,8 @@ import datadog.opentracing.DDTracer
 import datadog.opentracing.PendingTrace
 import datadog.trace.api.sampling.PrioritySampling
 import datadog.trace.common.writer.ListWriter
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.propagation.TextMapInjectAdapter
-import spock.lang.Specification
 
 import static datadog.opentracing.propagation.DatadogHttpCodec.ORIGIN_KEY
 import static datadog.opentracing.propagation.DatadogHttpCodec.OT_BAGGAGE_PREFIX
@@ -15,7 +15,7 @@ import static datadog.opentracing.propagation.DatadogHttpCodec.SPAN_ID_KEY
 import static datadog.opentracing.propagation.DatadogHttpCodec.TRACE_ID_KEY
 import static datadog.opentracing.propagation.HttpCodec.UINT64_MAX
 
-class DatadogHttpInjectorTest extends Specification {
+class DatadogHttpInjectorTest extends DDSpecification {
 
   HttpCodec.Injector injector = new DatadogHttpCodec.Injector()
 

dd-trace-ot/src/test/groovy/datadog/opentracing/propagation/HaystackHttpExtractorTest.groovy

@@ -1,16 +1,16 @@
 package datadog.opentracing.propagation
 
 import datadog.trace.api.sampling.PrioritySampling
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.SpanContext
 import io.opentracing.propagation.TextMapExtractAdapter
-import spock.lang.Specification
 
 import static datadog.opentracing.propagation.HaystackHttpCodec.OT_BAGGAGE_PREFIX
 import static datadog.opentracing.propagation.HaystackHttpCodec.SPAN_ID_KEY
 import static datadog.opentracing.propagation.HaystackHttpCodec.TRACE_ID_KEY
 import static datadog.opentracing.propagation.HttpCodec.UINT64_MAX
 
-class HaystackHttpExtractorTest extends Specification {
+class HaystackHttpExtractorTest extends DDSpecification {
 
   HttpCodec.Extractor extractor = new HaystackHttpCodec.Extractor(["SOME_HEADER": "some-tag"])
 

dd-trace-ot/src/test/groovy/datadog/opentracing/propagation/HaystackHttpInjectorTest.groovy

@@ -5,15 +5,15 @@ import datadog.opentracing.DDTracer
 import datadog.opentracing.PendingTrace
 import datadog.trace.api.sampling.PrioritySampling
 import datadog.trace.common.writer.ListWriter
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.propagation.TextMapInjectAdapter
-import spock.lang.Specification
 
 import static datadog.opentracing.propagation.HaystackHttpCodec.OT_BAGGAGE_PREFIX
 import static datadog.opentracing.propagation.HaystackHttpCodec.SPAN_ID_KEY
 import static datadog.opentracing.propagation.HaystackHttpCodec.TRACE_ID_KEY
 import static datadog.opentracing.propagation.HttpCodec.UINT64_MAX
 
-class HaystackHttpInjectorTest extends Specification {
+class HaystackHttpInjectorTest extends DDSpecification {
 
   HttpCodec.Injector injector = new HaystackHttpCodec.Injector()
 
@@ -55,7 +55,6 @@ class HaystackHttpInjectorTest extends Specification {
     1 * carrier.put(OT_BAGGAGE_PREFIX + "k2", "v2")
 
 
-
     where:
     traceId                        | spanId                         | samplingPriority              | origin
     "1"                            | "2"                            | PrioritySampling.SAMPLER_KEEP | null

dd-trace-ot/src/test/groovy/datadog/opentracing/propagation/HttpExtractorTest.groovy

@@ -1,20 +1,17 @@
 package datadog.opentracing.propagation
 
-import datadog.trace.agent.test.utils.ConfigUtils
+
 import datadog.trace.api.Config
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.SpanContext
 import io.opentracing.propagation.TextMapExtractAdapter
 import spock.lang.Shared
-import spock.lang.Specification
 
 import static datadog.opentracing.propagation.HttpCodec.UINT64_MAX
 import static datadog.trace.api.Config.PropagationStyle.B3
 import static datadog.trace.api.Config.PropagationStyle.DATADOG
 
-class HttpExtractorTest extends Specification {
+class HttpExtractorTest extends DDSpecification {
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
 
   @Shared
   String outOfRangeTraceId = UINT64_MAX.add(BigInteger.ONE)

dd-trace-ot/src/test/groovy/datadog/opentracing/propagation/HttpInjectorTest.groovy

@@ -3,20 +3,16 @@ package datadog.opentracing.propagation
 import datadog.opentracing.DDSpanContext
 import datadog.opentracing.DDTracer
 import datadog.opentracing.PendingTrace
-import datadog.trace.agent.test.utils.ConfigUtils
 import datadog.trace.api.Config
 import datadog.trace.api.sampling.PrioritySampling
 import datadog.trace.common.writer.ListWriter
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.propagation.TextMapInjectAdapter
-import spock.lang.Specification
 
 import static datadog.trace.api.Config.PropagationStyle.B3
 import static datadog.trace.api.Config.PropagationStyle.DATADOG
 
-class HttpInjectorTest extends Specification {
+class HttpInjectorTest extends DDSpecification {
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
 
   def "inject http headers"() {
     setup:

dd-trace-ot/src/test/groovy/datadog/opentracing/resolver/DDTracerResolverTest.groovy

@@ -1,15 +1,11 @@
 package datadog.opentracing.resolver
 
 import datadog.opentracing.DDTracer
-import datadog.trace.agent.test.utils.ConfigUtils
 import datadog.trace.api.Config
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.contrib.tracerresolver.TracerResolver
-import spock.lang.Specification
 
-class DDTracerResolverTest extends Specification {
+class DDTracerResolverTest extends DDSpecification {
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
 
   def resolver = new DDTracerResolver()
 

dd-trace-ot/src/test/groovy/datadog/opentracing/scopemanager/ScopeManagerTest.groovy

@@ -3,14 +3,13 @@ package datadog.opentracing.scopemanager
 import datadog.opentracing.DDSpan
 import datadog.opentracing.DDSpanContext
 import datadog.opentracing.DDTracer
-import datadog.trace.agent.test.utils.ConfigUtils
 import datadog.trace.common.writer.ListWriter
 import datadog.trace.context.ScopeListener
 import datadog.trace.util.gc.GCUtils
+import datadog.trace.util.test.DDSpecification
 import io.opentracing.Scope
 import io.opentracing.Span
 import io.opentracing.noop.NoopSpan
-import spock.lang.Specification
 import spock.lang.Subject
 import spock.lang.Timeout
 
@@ -22,10 +21,7 @@ import java.util.concurrent.atomic.AtomicReference
 
 import static java.util.concurrent.TimeUnit.SECONDS
 
-class ScopeManagerTest extends Specification {
+class ScopeManagerTest extends DDSpecification {
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
   def latch
   def writer
   def tracer

dd-trace-ot/src/test/groovy/datadog/trace/DDSpanContextTest.groovy

@@ -2,9 +2,9 @@ package datadog.trace
 
 import datadog.opentracing.SpanFactory
 import datadog.trace.api.DDTags
-import spock.lang.Specification
+import datadog.trace.util.test.DDSpecification
 
-class DDSpanContextTest extends Specification {
+class DDSpanContextTest extends DDSpecification {
 
   def "null values for tags delete existing tags"() {
     setup:

dd-trace-ot/src/test/groovy/datadog/trace/DDTracerTest.groovy

@@ -2,17 +2,16 @@ package datadog.trace
 
 import datadog.opentracing.DDTracer
 import datadog.opentracing.propagation.HttpCodec
-import datadog.trace.agent.test.utils.ConfigUtils
 import datadog.trace.api.Config
 import datadog.trace.common.sampling.AllSampler
 import datadog.trace.common.sampling.RateByServiceSampler
 import datadog.trace.common.writer.DDAgentWriter
 import datadog.trace.common.writer.ListWriter
 import datadog.trace.common.writer.LoggingWriter
+import datadog.trace.util.test.DDSpecification
 import org.junit.Rule
 import org.junit.contrib.java.lang.system.EnvironmentVariables
 import org.junit.contrib.java.lang.system.RestoreSystemProperties
-import spock.lang.Specification
 
 import static datadog.trace.api.Config.DEFAULT_SERVICE_NAME
 import static datadog.trace.api.Config.HEADER_TAGS
@@ -22,10 +21,7 @@ import static datadog.trace.api.Config.SERVICE_MAPPING
 import static datadog.trace.api.Config.SPAN_TAGS
 import static datadog.trace.api.Config.WRITER_TYPE
 
-class DDTracerTest extends Specification {
+class DDTracerTest extends DDSpecification {
-  static {
-    ConfigUtils.makeConfigInstanceModifiable()
-  }
 
   @Rule
   public final RestoreSystemProperties restoreSystemProperties = new RestoreSystemProperties()

dd-trace-ot/src/test/groovy/datadog/trace/api/sampling/AllSamplerTest.groovy

@@ -0,0 +1,42 @@
+package datadog.trace.api.sampling
+
+import datadog.opentracing.DDSpan
+import datadog.trace.common.sampling.AllSampler
+import datadog.trace.util.test.DDSpecification
+import spock.lang.Subject
+
+import java.util.regex.Pattern
+
+class AllSamplerTest extends DDSpecification {
+
+  @Subject
+  DDSpan span = Mock()
+
+  private final AllSampler sampler = new AllSampler()
+
+  def "test AllSampler"() {
+    expect:
+    for (int i = 0; i < 500; i++) {
+      assert sampler.doSample(span)
+    }
+  }
+
+  def "test skip tag sampler"() {
+    setup:
+    final Map<String, Object> tags = new HashMap<>()
+    2 * span.getTags() >> tags
+    sampler.addSkipTagPattern("http.url", Pattern.compile(".*/hello"))
+
+    when:
+    tags.put("http.url", "http://a/hello")
+
+    then:
+    !sampler.sample(span)
+
+    when:
+    tags.put("http.url", "http://a/hello2")
+
+    then:
+    sampler.sample(span)
+  }
+}

dd-trace-ot/src/test/groovy/datadog/trace/api/sampling/RateByServiceSamplerTest.groovy

@@ -4,11 +4,11 @@ import com.fasterxml.jackson.databind.ObjectMapper
 import datadog.opentracing.DDSpan
 import datadog.opentracing.SpanFactory
 import datadog.trace.common.sampling.RateByServiceSampler
-import spock.lang.Specification
+import datadog.trace.util.test.DDSpecification
 
 import static datadog.trace.common.sampling.RateByServiceSampler.DEFAULT_KEY
 
-class RateByServiceSamplerTest extends Specification {
+class RateByServiceSamplerTest extends DDSpecification {
 
   def "invalid rate -> 1"() {
     setup:

dd-trace-ot/src/test/groovy/datadog/trace/api/writer/DDAgentWriterTest.groovy

@@ -7,7 +7,7 @@ import datadog.opentracing.PendingTrace
 import datadog.trace.api.sampling.PrioritySampling
 import datadog.trace.common.writer.DDAgentWriter
 import datadog.trace.common.writer.DDApi
-import spock.lang.Specification
+import datadog.trace.util.test.DDSpecification
 import spock.lang.Timeout
 
 import java.util.concurrent.TimeUnit
@@ -16,7 +16,7 @@ import static datadog.opentracing.SpanFactory.newSpanOf
 import static datadog.trace.common.writer.DDAgentWriter.DISRUPTOR_BUFFER_SIZE
 
 @Timeout(20)
-class DDAgentWriterTest extends Specification {
+class DDAgentWriterTest extends DDSpecification {
 
   def api = Mock(DDApi)
 

dd-trace-ot/src/test/groovy/datadog/trace/api/writer/DDApiTest.groovy

@@ -5,14 +5,14 @@ import com.fasterxml.jackson.databind.JsonNode
 import datadog.opentracing.SpanFactory
 import datadog.trace.common.writer.DDApi
 import datadog.trace.common.writer.DDApi.ResponseListener
-import spock.lang.Specification
+import datadog.trace.util.test.DDSpecification
 
 import java.util.concurrent.atomic.AtomicLong
 import java.util.concurrent.atomic.AtomicReference
 
 import static datadog.trace.agent.test.server.http.TestHttpServer.httpServer
 
-class DDApiTest extends Specification {
+class DDApiTest extends DDSpecification {
   static mapper = DDApi.OBJECT_MAPPER
 
   def "sending an empty list of traces returns no errors"() {

dd-trace-ot/src/test/groovy/datadog/trace/api/writer/SerializationTest.groovy

@@ -1,16 +1,15 @@
 package datadog.trace.api.writer
 
-
 import com.fasterxml.jackson.core.type.TypeReference
 import com.fasterxml.jackson.databind.ObjectMapper
+import datadog.trace.util.test.DDSpecification
 import org.msgpack.core.MessagePack
 import org.msgpack.jackson.dataformat.MessagePackFactory
 import spock.lang.Shared
-import spock.lang.Specification
 
 import static java.util.Collections.singletonMap
 
-class SerializationTest extends Specification {
+class SerializationTest extends DDSpecification {
   @Shared
   def jsonMapper = new ObjectMapper()
   @Shared

dd-trace-ot/src/test/java/datadog/trace/api/sampling/AllSamplerTest.java

@@ -1,44 +0,0 @@
-package datadog.trace.api.sampling;
-
-import static org.assertj.core.api.Assertions.assertThat;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.when;
-
-import datadog.opentracing.DDSpan;
-import datadog.trace.common.sampling.AllSampler;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.regex.Pattern;
-import org.junit.Test;
-import org.mockito.Mock;
-
-public class AllSamplerTest {
-
-  @Mock DDSpan mockSpan;
-
-  private final AllSampler sampler = new AllSampler();
-
-  @Test
-  public void testAllSampler() {
-
-    for (int i = 0; i < 500; i++) {
-      assertThat(sampler.doSample(mockSpan)).isTrue();
-    }
-  }
-
-  @Test
-  public void testSkipTagPatternSampler() {
-
-    final Map<String, Object> tags = new HashMap<>();
-    mockSpan = mock(DDSpan.class);
-    when(mockSpan.getTags()).thenReturn(tags).thenReturn(tags);
-
-    sampler.addSkipTagPattern("http.url", Pattern.compile(".*/hello"));
-
-    tags.put("http.url", "http://a/hello");
-    assertThat(sampler.sample(mockSpan)).isFalse();
-
-    tags.put("http.url", "http://a/hello2");
-    assertThat(sampler.sample(mockSpan)).isTrue();
-  }
-}

dd-trace-ot/src/traceAgentTest/groovy/DDApiIntegrationTest.groovy

@@ -6,11 +6,11 @@ import datadog.opentracing.PendingTrace
 import datadog.trace.api.sampling.PrioritySampling
 import datadog.trace.common.writer.DDApi
 import datadog.trace.common.writer.ListWriter
+import datadog.trace.util.test.DDSpecification
 import org.testcontainers.containers.GenericContainer
 import org.testcontainers.containers.startupcheck.MinimumDurationRunningStartupCheckStrategy
 import spock.lang.Requires
 import spock.lang.Shared
-import spock.lang.Specification
 
 import java.time.Duration
 import java.util.concurrent.TimeUnit
@@ -20,7 +20,7 @@ class DDApiIntegrationTest {
   // Do not run tests locally on Java7 since testcontainers are not compatible with Java7
   // It is fine to run on CI because CI provides rabbitmq externally, not through testcontainers
   @Requires({ "true" == System.getenv("CI") || jvm.java8Compatible })
-  static class DDApiIntegrationV4Test extends Specification {
+  static class DDApiIntegrationV4Test extends DDSpecification {
     static final WRITER = new ListWriter()
     static final TRACER = new DDTracer(WRITER)
     static final CONTEXT = new DDSpanContext(

gradle/dependencies.gradle

@@ -49,9 +49,14 @@ ext {
     ],
 
     // Testing
-    spock          : dependencies.create("org.spockframework:spock-core:${versions.spock}", {
+
+    spock          : [
+      dependencies.create("org.spockframework:spock-core:${versions.spock}", {
         exclude group: 'org.codehaus.groovy', module: 'groovy-all'
       }),
+      // Used by Spock for mocking:
+      dependencies.create(group: 'org.objenesis', name: 'objenesis', version: '2.6') // Last version to support Java7
+    ],
     groovy         : "org.codehaus.groovy:groovy-all:${versions.groovy}",
     junit          : "junit:junit:${versions.junit}",
     testcontainers : "org.testcontainers:testcontainers:1.7.3",

settings.gradle

@@ -13,6 +13,7 @@ include ':dd-java-agent:agent-jmxfetch'
 // misc
 include ':dd-java-agent:testing'
 include ':utils:gc-utils'
+include ':utils:test-utils'
 
 // smoke tests
 include ':dd-smoke-tests:cli'

utils/test-utils/src/main/groovy/datadog/trace/util/test/DDSpecification.groovy

@@ -0,0 +1,78 @@
+package datadog.trace.util.test
+
+import net.bytebuddy.agent.ByteBuddyAgent
+import net.bytebuddy.agent.builder.AgentBuilder
+import net.bytebuddy.dynamic.ClassFileLocator
+import net.bytebuddy.dynamic.Transformer
+import spock.lang.Specification
+
+import java.lang.reflect.Modifier
+
+import static net.bytebuddy.description.modifier.FieldManifestation.VOLATILE
+import static net.bytebuddy.description.modifier.Ownership.STATIC
+import static net.bytebuddy.description.modifier.Visibility.PUBLIC
+import static net.bytebuddy.matcher.ElementMatchers.named
+import static net.bytebuddy.matcher.ElementMatchers.none
+
+abstract class DDSpecification extends Specification {
+  private static final String CONFIG = "datadog.trace.api.Config"
+
+  static class ConfigInstance {
+    // Wrapped in a static class to lazy load.
+    static final CONFIG_INSTANCE_FIELD = Class.forName(CONFIG).getDeclaredField("INSTANCE")
+    static final RUNTIME_ID_FIELD = Class.forName(CONFIG).getDeclaredField("runtimeId")
+  }
+
+  static {
+    makeConfigInstanceModifiable()
+  }
+
+  // Keep track of config instance already made modifiable
+  private static isConfigInstanceModifiable = false
+
+  static void makeConfigInstanceModifiable() {
+    if (isConfigInstanceModifiable) {
+      return
+    }
+
+    def instrumentation = ByteBuddyAgent.install()
+    final transformer =
+      new AgentBuilder.Default()
+        .with(AgentBuilder.RedefinitionStrategy.RETRANSFORMATION)
+        .with(AgentBuilder.RedefinitionStrategy.Listener.ErrorEscalating.FAIL_FAST)
+      // Config is injected into the bootstrap, so we need to provide a locator.
+        .with(
+          new AgentBuilder.LocationStrategy.Simple(
+            ClassFileLocator.ForClassLoader.ofSystemLoader()))
+        .ignore(none()) // Allow transforming bootstrap classes
+        .type(named(CONFIG))
+        .transform { builder, typeDescription, classLoader, module ->
+          builder
+            .field(named("INSTANCE"))
+            .transform(Transformer.ForField.withModifiers(PUBLIC, STATIC, VOLATILE))
+        }
+      // Making runtimeId modifiable so that it can be preserved when resetting config in tests
+        .transform { builder, typeDescription, classLoader, module ->
+          builder
+            .field(named("runtimeId"))
+            .transform(Transformer.ForField.withModifiers(PUBLIC, VOLATILE))
+        }
+        .installOn(instrumentation)
+    isConfigInstanceModifiable = true
+
+    final field = ConfigInstance.CONFIG_INSTANCE_FIELD
+    assert Modifier.isPublic(field.getModifiers())
+    assert Modifier.isStatic(field.getModifiers())
+    assert Modifier.isVolatile(field.getModifiers())
+    assert !Modifier.isFinal(field.getModifiers())
+
+    final runtimeIdField = ConfigInstance.RUNTIME_ID_FIELD
+    assert Modifier.isPublic(runtimeIdField.getModifiers())
+    assert !Modifier.isStatic(ConfigInstance.RUNTIME_ID_FIELD.getModifiers())
+    assert Modifier.isVolatile(runtimeIdField.getModifiers())
+    assert !Modifier.isFinal(runtimeIdField.getModifiers())
+
+    // No longer needed (Unless class gets retransformed somehow).
+    instrumentation.removeTransformer(transformer)
+  }
+}

utils/test-utils/test-utils.gradle

@@ -0,0 +1,9 @@
+apply from: "${rootDir}/gradle/java.gradle"
+
+dependencies {
+  compile deps.groovy
+  compile deps.spock
+
+  compile deps.bytebuddy
+  compile deps.bytebuddyagent
+}