1) instrumentation requires a single plugin jar and the runtime jar must be also be supplied on the classpath

2) testing instrumented code does not require the plugin jar
3) reporting on coverage files requires all scoverage jars.

Author: maiflai

src/main/groovy/org/scoverage/ScoverageExtension.groovy

@@ -2,7 +2,8 @@ package org.scoverage
 
 import org.gradle.api.Action
 import org.gradle.api.Project
-import org.gradle.api.artifacts.ResolvedConfiguration
+import org.gradle.api.artifacts.Configuration
+import org.gradle.api.file.FileCollection
 import org.gradle.api.plugins.JavaPlugin
 import org.gradle.api.plugins.scala.ScalaPlugin
 import org.gradle.api.tasks.JavaExec
@@ -77,13 +78,14 @@ class ScoverageExtension {
             extension.dataDir.mkdirs()
             extension.reportDir.mkdirs()
 
-            ResolvedConfiguration s = t.configurations[ScoveragePlugin.CONFIGURATION_NAME].resolvedConfiguration
-            String pluginPath = s.getFirstLevelModuleDependencies().iterator().next().moduleArtifacts.iterator().next().file.absolutePath
+            Configuration configuration = t.configurations[ScoveragePlugin.CONFIGURATION_NAME]
+            File pluginFile = configuration.filter { it.name.contains('plugin') }.iterator().next()
+            FileCollection pluginDependencies = configuration.filter { it != pluginFile }
 
             t.tasks[ScoveragePlugin.COMPILE_NAME].configure {
 
 
-                List<String> plugin = ['-Xplugin:' + pluginPath]
+                List<String> plugin = ['-Xplugin:' + pluginFile.absolutePath]
                 List<String> parameters = scalaCompileOptions.additionalParameters
                 if (parameters != null) {
                     plugin.addAll(parameters)
@@ -100,19 +102,18 @@ class ScoverageExtension {
                 }
                 scalaCompileOptions.additionalParameters = plugin
                 // exclude the scala libraries that are added to enable scala version detection
-                classpath += t.configurations[ScoveragePlugin.CONFIGURATION_NAME]
+                classpath += pluginDependencies
             }
 
             t.tasks[ScoveragePlugin.TEST_NAME].configure {
                 def existingClasspath = classpath
                 classpath = t.files(t.sourceSets[ScoveragePlugin.CONFIGURATION_NAME].output.classesDir) +
-                        project.configurations[ScoveragePlugin.CONFIGURATION_NAME] +
+                        pluginDependencies +
                         existingClasspath
             }
 
             t.tasks[ScoveragePlugin.REPORT_NAME].configure {
-                classpath = project.buildscript.configurations.classpath +
-                        project.configurations[ScoveragePlugin.CONFIGURATION_NAME]
+                classpath = project.buildscript.configurations.classpath + configuration
                 main = 'org.scoverage.ScoverageReport'
                 args = [
                         extension.sources,