Don't override methods that already exist in unit test mixins. Fixes #10201

Author: graemerocher

grails-plugin-testing/src/main/groovy/org/grails/compiler/injection/test/TestMixinTransformation.java

@@ -217,7 +217,7 @@ protected void weaveMixinIntoClass(final ClassNode classNode, final ClassNode mi
 
         boolean implementsTestRuntimeAwareMixin = GrailsASTUtils.findInterface(mixinClassNode, ClassHelper.make(TestRuntimeAwareMixin.class)) != null;
 
-        FieldNode mixinFieldNode = null;
+        FieldNode mixinFieldNode;
         if(!implementsTestRuntimeAwareMixin) { 
             mixinFieldNode = addLegacyMixinFieldIfNonExistent(classNode, mixinClassNode, fieldName);
         } else {
@@ -395,7 +395,7 @@ static protected FieldNode addLegacyMixinFieldIfNonExistent(ClassNode classNode,
     }
 
     static protected boolean hasDeclaredMethod(ClassNode classNode, MethodNode mixinMethod) {
-        return classNode.hasDeclaredMethod(mixinMethod.getName(), mixinMethod.getParameters());
+        return classNode.hasMethod(mixinMethod.getName(), mixinMethod.getParameters());
     }
 
     static protected boolean hasAnnotation(MethodNode mixinMethod, Class<?> beforeClass) {

grails-test-suite-uber/src/test/groovy/grails/test/mixin/ServiceTestMixinInheritanceSpec.groovy

@@ -0,0 +1,31 @@
+package grails.test.mixin
+
+import grails.artefact.Artefact
+import grails.test.mixin.services.ServiceUnitTestMixin
+import org.grails.core.artefact.ServiceArtefactHandler
+import org.grails.datastore.mapping.transactions.DatastoreTransactionManager
+import org.springframework.transaction.PlatformTransactionManager
+import spock.lang.Specification
+
+/**
+ * Created by graemerocher on 04/10/2016.
+ */
+@TestMixin(ServiceUnitTestMixin)
+class ServiceTestMixinInheritanceSpec extends TestSuperClass {
+
+    void "Test inherit transaction manager"() {
+        expect:
+        transactionManager.is(TestSuperClass.manager)
+    }
+}
+@Artefact(ServiceArtefactHandler.TYPE)
+class TestService {
+
+}
+class TestSuperClass extends Specification {
+    public static final DatastoreTransactionManager manager = new DatastoreTransactionManager()
+
+    PlatformTransactionManager getTransactionManager() {
+        return manager
+    }
+}