diff --git a/src/main/dig/generic/gray/GrayCounter.dig b/src/main/dig/generic/gray/GrayCounter.dig
index 7d76ae064..734c6184a 100644
--- a/src/main/dig/generic/gray/GrayCounter.dig
+++ b/src/main/dig/generic/gray/GrayCounter.dig
@@ -47,8 +47,19 @@ C 0
 </dataString>
           </testData>
         </entry>
+        <entry>
+          <string>generic</string>
+          <string>?&gt;C G
+0 0
+loop (n,(1&lt;&lt; &lt;?=args.bits?&gt; )-1)
+C ((n+1) ^ ((n+1)&gt;&gt;1))
+end loop
+C 0&lt;?
+
+this.Testdata=output();</string>
+        </entry>
       </elementAttributes>
-      <pos x="620" y="40"/>
+      <pos x="680" y="40"/>
     </visualElement>
     <visualElement>
       <elementName>Text</elementName>
@@ -153,7 +164,7 @@ if (args.bits&gt;3) {
           <string>bits := 3;</string>
         </entry>
       </elementAttributes>
-      <pos x="200" y="160"/>
+      <pos x="680" y="100"/>
     </visualElement>
   </visualElements>
   <wires>
diff --git a/src/main/java/de/neemann/digital/cli/CommandLineTester.java b/src/main/java/de/neemann/digital/cli/CommandLineTester.java
index 55fab611a..7bc3432d9 100644
--- a/src/main/java/de/neemann/digital/cli/CommandLineTester.java
+++ b/src/main/java/de/neemann/digital/cli/CommandLineTester.java
@@ -10,17 +10,14 @@ import de.neemann.digital.cli.cli.BasicCommand;
 import de.neemann.digital.cli.cli.CLIException;
 import de.neemann.digital.core.ErrorDetector;
 import de.neemann.digital.core.Model;
-import de.neemann.digital.core.element.Keys;
 import de.neemann.digital.draw.elements.Circuit;
-import de.neemann.digital.draw.elements.VisualElement;
 import de.neemann.digital.lang.Lang;
-import de.neemann.digital.testing.TestCaseDescription;
 import de.neemann.digital.testing.TestExecutor;
 
 import java.io.File;
 import java.io.IOException;
 import java.io.PrintStream;
-import java.util.ArrayList;
+import java.util.List;
 
 /**
  * Tester used from the command line
@@ -28,7 +25,7 @@ import java.util.ArrayList;
 public class CommandLineTester {
 
     private final CircuitLoader circuitLoader;
-    private ArrayList<TestCase> testCases;
+    private List<Circuit.TestCase> testCases;
     private int testsPassed;
     private boolean allowMissingInputs;
 
@@ -51,19 +48,10 @@ public class CommandLineTester {
      */
     public CommandLineTester useTestCasesFrom(File file) throws IOException {
         Circuit c = Circuit.loadCircuit(file, circuitLoader.getShapeFactory());
-        testCases = getTestCasesFrom(c);
+        testCases = c.getTestCases();
         return this;
     }
 
-    private ArrayList<TestCase> getTestCasesFrom(Circuit circuit) {
-        ArrayList<TestCase> tsl = new ArrayList<>();
-        for (VisualElement el : circuit.getTestCases())
-            tsl.add(new TestCase(
-                    el.getElementAttributes().get(Keys.TESTDATA),
-                    el.getElementAttributes().getLabel()));
-        return tsl;
-    }
-
     /**
      * Executes test test
      *
@@ -72,7 +60,7 @@ public class CommandLineTester {
      */
     public int execute(PrintStream out) {
         if (testCases == null)
-            testCases = getTestCasesFrom(circuitLoader.getCircuit());
+            testCases = circuitLoader.getCircuit().getTestCases();
 
         int errorCount = 0;
 
@@ -80,7 +68,7 @@ public class CommandLineTester {
             out.println("no test cases given");
             errorCount++;
         } else {
-            for (TestCase t : testCases) {
+            for (Circuit.TestCase t : testCases) {
                 String label = t.getLabel();
                 if (label.isEmpty())
                     label = "unnamed";
@@ -123,24 +111,6 @@ public class CommandLineTester {
         return testsPassed;
     }
 
-    private static final class TestCase {
-        private final TestCaseDescription testCaseDescription;
-        private final String label;
-
-        private TestCase(TestCaseDescription testCaseDescription, String label) {
-            this.testCaseDescription = testCaseDescription;
-            this.label = label;
-        }
-
-        private TestCaseDescription getTestCaseDescription() {
-            return testCaseDescription;
-        }
-
-        private String getLabel() {
-            return label;
-        }
-    }
-
     private CommandLineTester setAllowMissingInputs(boolean allowMissingInputs) {
         this.allowMissingInputs = allowMissingInputs;
         return this;
diff --git a/src/main/java/de/neemann/digital/draw/elements/Circuit.java b/src/main/java/de/neemann/digital/draw/elements/Circuit.java
index c9c3ef809..ee5ac4187 100644
--- a/src/main/java/de/neemann/digital/draw/elements/Circuit.java
+++ b/src/main/java/de/neemann/digital/draw/elements/Circuit.java
@@ -348,8 +348,41 @@ public class Circuit implements Copyable<Circuit> {
      *
      * @return the test case elements
      */
-    public List<VisualElement> getTestCases() {
-        return getElements(v -> v.equalsDescription(TestCaseElement.TESTCASEDESCRIPTION) && v.getElementAttributes().get(Keys.ENABLED));
+    public List<TestCase> getTestCases() {
+        ArrayList<TestCase> tc = new ArrayList<>();
+        for (VisualElement ve : getElements(v -> v.equalsDescription(TestCaseElement.TESTCASEDESCRIPTION) && v.getElementAttributes().get(Keys.ENABLED))) {
+            tc.add(new TestCase(
+                    ve.getElementAttributes().getLabel(),
+                    new TestCaseDescription(ve.getElementAttributes().get(Keys.TESTDATA))));
+        }
+        return tc;
+    }
+
+    /**
+     * A simple java bean to encapsulate a test case description
+     */
+    public static final class TestCase {
+        private final String label;
+        private final TestCaseDescription testCaseDescription;
+
+        private TestCase(String label, TestCaseDescription testCaseDescription) {
+            this.label = label;
+            this.testCaseDescription = testCaseDescription;
+        }
+
+        /**
+         * @return the label of the test case
+         */
+        public String getLabel() {
+            return label;
+        }
+
+        /**
+         * @return the test case description
+         */
+        public TestCaseDescription getTestCaseDescription() {
+            return testCaseDescription;
+        }
     }
 
     /**
diff --git a/src/main/java/de/neemann/digital/gui/Main.java b/src/main/java/de/neemann/digital/gui/Main.java
index d38fe2ec6..e22afd582 100644
--- a/src/main/java/de/neemann/digital/gui/Main.java
+++ b/src/main/java/de/neemann/digital/gui/Main.java
@@ -1128,10 +1128,8 @@ public final class Main extends JFrame implements ClosingWindowListener.ConfirmS
     public void startTests() {
         try {
             ArrayList<ValueTableDialog.TestSet> tsl = new ArrayList<>();
-            for (VisualElement el : circuitComponent.getCircuit().getTestCases())
-                tsl.add(new ValueTableDialog.TestSet(
-                        el.getElementAttributes().get(Keys.TESTDATA),
-                        el.getElementAttributes().getLabel()));
+            for (Circuit.TestCase tc : circuitComponent.getCircuit().getTestCases())
+                tsl.add(new ValueTableDialog.TestSet(tc.getTestCaseDescription(), tc.getLabel()));
 
             if (tsl.isEmpty())
                 throw new TestingDataException(Lang.get("err_noTestData"));
diff --git a/src/main/java/de/neemann/digital/hdl/verilog2/VerilogTestBenchCreator.java b/src/main/java/de/neemann/digital/hdl/verilog2/VerilogTestBenchCreator.java
index d3d390c8e..a2a5d58d1 100644
--- a/src/main/java/de/neemann/digital/hdl/verilog2/VerilogTestBenchCreator.java
+++ b/src/main/java/de/neemann/digital/hdl/verilog2/VerilogTestBenchCreator.java
@@ -5,17 +5,15 @@
  */
 package de.neemann.digital.hdl.verilog2;
 
-import de.neemann.digital.hdl.vhdl2.*;
-import de.neemann.digital.core.element.ElementAttributes;
 import de.neemann.digital.data.Value;
 import de.neemann.digital.draw.elements.Circuit;
-import de.neemann.digital.draw.elements.VisualElement;
 import de.neemann.digital.hdl.model2.HDLCircuit;
 import de.neemann.digital.hdl.model2.HDLException;
 import de.neemann.digital.hdl.model2.HDLModel;
 import de.neemann.digital.hdl.model2.HDLPort;
 import de.neemann.digital.hdl.printer.CodePrinter;
 import de.neemann.digital.hdl.printer.CodePrinterStr;
+import de.neemann.digital.hdl.vhdl2.Separator;
 import de.neemann.digital.lang.Lang;
 import de.neemann.digital.testing.TestCaseDescription;
 import de.neemann.digital.testing.TestingDataException;
@@ -27,9 +25,7 @@ import de.neemann.digital.testing.parser.TestRow;
 import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
-
-import static de.neemann.digital.core.element.Keys.TESTDATA;
-
+import java.util.List;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -38,7 +34,7 @@ import java.util.logging.Logger;
  * The needed test date is taken from the test cases in the circuit
  */
 public class VerilogTestBenchCreator {
-    private final ArrayList<ElementAttributes> testCases;
+    private final List<Circuit.TestCase> testCases;
     private final HDLCircuit main;
     private final String topModuleName;
     private final HDLModel.Renaming renaming;
@@ -54,9 +50,7 @@ public class VerilogTestBenchCreator {
     public VerilogTestBenchCreator(Circuit circuit, HDLModel model, String topModuleName) {
         this.main = model.getMain();
         this.topModuleName = topModuleName;
-        testCases = new ArrayList<>();
-        for (VisualElement ve : circuit.getTestCases())
-            testCases.add(ve.getElementAttributes());
+        testCases = circuit.getTestCases();
         testFileWritten = new ArrayList<>();
         renaming = model.getRenaming();
     }
@@ -75,7 +69,7 @@ public class VerilogTestBenchCreator {
         if (p > 0)
             filename = filename.substring(0, p);
 
-        for (ElementAttributes tc : testCases) {
+        for (Circuit.TestCase tc : testCases) {
             String testName = tc.getLabel();
             if (testName.length() > 0)
                 testName = filename + "_" + testName + "_tb";
@@ -107,7 +101,7 @@ public class VerilogTestBenchCreator {
         return testFileWritten;
     }
 
-    private void writeTestBench(CodePrinter out, String moduleName, String testName, ElementAttributes tc) throws IOException, HDLException, TestingDataException, ParserException {
+    private void writeTestBench(CodePrinter out, String moduleName, String testName, Circuit.TestCase tc) throws IOException, HDLException, TestingDataException, ParserException {
         out.print("//  A testbench for ").println(testName);
         out.println("`timescale 1us/1ns").println();
         out.print("module ").print(testName).println(";");
@@ -131,7 +125,7 @@ public class VerilogTestBenchCreator {
         }
         out.dec().println().print(");").println().println();
 
-        TestCaseDescription testdata = tc.get(TESTDATA);
+        TestCaseDescription testdata = tc.getTestCaseDescription();
 
         ArrayList<HDLPort> dataOrder = new ArrayList<>();
         ArrayList<HDLPort> inputsInOrder = new ArrayList<>();
diff --git a/src/main/java/de/neemann/digital/hdl/vhdl2/VHDLTestBenchCreator.java b/src/main/java/de/neemann/digital/hdl/vhdl2/VHDLTestBenchCreator.java
index df0b058c0..6f8ac0c02 100644
--- a/src/main/java/de/neemann/digital/hdl/vhdl2/VHDLTestBenchCreator.java
+++ b/src/main/java/de/neemann/digital/hdl/vhdl2/VHDLTestBenchCreator.java
@@ -5,10 +5,8 @@
  */
 package de.neemann.digital.hdl.vhdl2;
 
-import de.neemann.digital.core.element.ElementAttributes;
 import de.neemann.digital.data.Value;
 import de.neemann.digital.draw.elements.Circuit;
-import de.neemann.digital.draw.elements.VisualElement;
 import de.neemann.digital.hdl.model2.HDLCircuit;
 import de.neemann.digital.hdl.model2.HDLException;
 import de.neemann.digital.hdl.model2.HDLModel;
@@ -25,15 +23,14 @@ import de.neemann.digital.testing.parser.TestRow;
 import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
-
-import static de.neemann.digital.core.element.Keys.TESTDATA;
+import java.util.List;
 
 /**
  * Creates a test bench for a model.
  * The needed test data is taken from the test cases in the circuit
  */
 public class VHDLTestBenchCreator {
-    private final ArrayList<ElementAttributes> testCases;
+    private final List<Circuit.TestCase> testCases;
     private final HDLCircuit main;
     private final HDLModel.Renaming renaming;
     private ArrayList<File> testFileWritten;
@@ -47,9 +44,7 @@ public class VHDLTestBenchCreator {
     VHDLTestBenchCreator(Circuit circuit, HDLModel model) {
         this.main = model.getMain();
         this.renaming = model.getRenaming();
-        testCases = new ArrayList<>();
-        for (VisualElement ve : circuit.getTestCases())
-            testCases.add(ve.getElementAttributes());
+        testCases = circuit.getTestCases();
         testFileWritten = new ArrayList<>();
     }
 
@@ -68,7 +63,7 @@ public class VHDLTestBenchCreator {
             filename = filename.substring(0, p);
 
         VHDLRenaming renaming = new VHDLRenaming();
-        for (ElementAttributes tc : testCases) {
+        for (Circuit.TestCase tc : testCases) {
             String testName = tc.getLabel();
             if (testName.length() > 0) {
                 testName = filename + "_" + renaming.checkName(testName) + "_tb";
@@ -95,7 +90,7 @@ public class VHDLTestBenchCreator {
         return testFileWritten;
     }
 
-    private void writeTestBench(CodePrinter out, String testName, ElementAttributes tc) throws IOException, TestingDataException, ParserException {
+    private void writeTestBench(CodePrinter out, String testName, Circuit.TestCase tc) throws IOException, TestingDataException, ParserException {
         out.print("--  A testbench for ").println(testName);
         out.println("LIBRARY ieee;");
         out.println("USE ieee.std_logic_1164.all;");
@@ -140,7 +135,7 @@ public class VHDLTestBenchCreator {
 
         out.println("process").inc();
 
-        TestCaseDescription testdata = tc.get(TESTDATA);
+        TestCaseDescription testdata = tc.getTestCaseDescription();
 
         ArrayList<HDLPort> dataOrder = new ArrayList<>();
         out.println("type pattern_type is record").inc();
diff --git a/src/main/java/de/neemann/digital/testing/FolderTestRunner.java b/src/main/java/de/neemann/digital/testing/FolderTestRunner.java
index 03b7f7b7c..1bea6fc4e 100644
--- a/src/main/java/de/neemann/digital/testing/FolderTestRunner.java
+++ b/src/main/java/de/neemann/digital/testing/FolderTestRunner.java
@@ -7,10 +7,8 @@ package de.neemann.digital.testing;
 
 import de.neemann.digital.core.Model;
 import de.neemann.digital.core.NodeException;
-import de.neemann.digital.core.element.Keys;
 import de.neemann.digital.draw.elements.Circuit;
 import de.neemann.digital.draw.elements.PinException;
-import de.neemann.digital.draw.elements.VisualElement;
 import de.neemann.digital.draw.library.ElementLibrary;
 import de.neemann.digital.draw.library.ElementNotFoundException;
 import de.neemann.digital.draw.model.ModelCreator;
@@ -23,6 +21,7 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Comparator;
+import java.util.List;
 
 /**
  * Runs all tests in al circuits in a folder
@@ -186,12 +185,7 @@ public class FolderTestRunner {
                 FileToTest f = files.get(i);
                 try {
                     Circuit circuit = Circuit.loadCircuit(f.file, shapeFactory);
-                    ArrayList<TestCase> testCases = new ArrayList<>();
-                    for (VisualElement el : circuit.getTestCases()) {
-                        String label = el.getElementAttributes().getLabel();
-                        TestCaseDescription testData = el.getElementAttributes().get(Keys.TESTDATA);
-                        testCases.add(new TestCase(label, testData));
-                    }
+                    List<Circuit.TestCase> testCases = circuit.getTestCases();
                     if (testCases.isEmpty()) {
                         // if no test data is available, at least check if the model is error free
                         try {
@@ -204,21 +198,21 @@ public class FolderTestRunner {
                     } else {
                         StringBuilder sb = new StringBuilder();
                         int rowCount = 0;
-                        for (TestCase tc : testCases) {
+                        for (Circuit.TestCase tc : testCases) {
                             Model model = new ModelCreator(circuit, library).createModel(false);
                             try {
-                                TestExecutor te = new TestExecutor(tc.testData).create(model);
+                                TestExecutor te = new TestExecutor(tc.getTestCaseDescription()).create(model);
                                 if (te.allPassed()) {
                                     rowCount += te.getResult().getRows();
                                 } else {
                                     if (sb.length() > 0)
                                         sb.append("; ");
-                                    sb.append(Lang.get("msg_test_N_Failed", tc.label));
+                                    sb.append(Lang.get("msg_test_N_Failed", tc.getLabel()));
                                 }
                             } catch (TestingDataException | NodeException e) {
                                 if (sb.length() > 0)
                                     sb.append("; ");
-                                sb.append(tc.label).append(": ").append(e.getMessage());
+                                sb.append(tc.getLabel()).append(": ").append(e.getMessage());
                             }
                         }
                         if (sb.length() == 0) {
@@ -240,16 +234,6 @@ public class FolderTestRunner {
         }
     }
 
-    private static final class TestCase {
-        private final String label;
-        private final TestCaseDescription testData;
-
-        private TestCase(String label, TestCaseDescription testData) {
-            this.label = label;
-            this.testData = testData;
-        }
-    }
-
     /**
      * Interface to notify a listener for changes
      */
diff --git a/src/test/java/de/neemann/digital/draw/library/JarComponentManagerTest.java b/src/test/java/de/neemann/digital/draw/library/JarComponentManagerTest.java
index 163f961e3..d8682141d 100644
--- a/src/test/java/de/neemann/digital/draw/library/JarComponentManagerTest.java
+++ b/src/test/java/de/neemann/digital/draw/library/JarComponentManagerTest.java
@@ -6,6 +6,7 @@
 package de.neemann.digital.draw.library;
 
 import de.neemann.digital.core.element.Keys;
+import de.neemann.digital.draw.elements.Circuit;
 import de.neemann.digital.draw.elements.VisualElement;
 import de.neemann.digital.integration.Resources;
 import de.neemann.digital.integration.ToBreakRunner;
@@ -36,13 +37,7 @@ public class JarComponentManagerTest extends TestCase {
             }
         };
 
-        for (VisualElement ve : br.getCircuit().getElements()) {
-            if (ve.equalsDescription(TestCaseElement.TESTCASEDESCRIPTION)) {
-                TestCaseDescription td = ve.getElementAttributes().get(Keys.TESTDATA);
-                TestExecutor tr = new TestExecutor(td).create(br.getModel());
-                assertTrue(tr.allPassed());
-            }
-        }
+        for (Circuit.TestCase tc : br.getCircuit().getTestCases())
+            assertTrue(new TestExecutor(tc.getTestCaseDescription()).create(br.getModel()).allPassed());
     }
-
 }
diff --git a/src/test/java/de/neemann/digital/integration/TestExamples.java b/src/test/java/de/neemann/digital/integration/TestExamples.java
index d5d1e4e39..ef540faec 100644
--- a/src/test/java/de/neemann/digital/integration/TestExamples.java
+++ b/src/test/java/de/neemann/digital/integration/TestExamples.java
@@ -18,7 +18,6 @@ import de.neemann.digital.draw.library.GenericInitCode;
 import de.neemann.digital.draw.library.ResolveGenerics;
 import de.neemann.digital.draw.model.ModelCreator;
 import de.neemann.digital.testing.TestCaseDescription;
-import de.neemann.digital.testing.TestCaseElement;
 import de.neemann.digital.testing.TestExecutor;
 import junit.framework.TestCase;
 
@@ -79,29 +78,28 @@ public class TestExamples extends TestCase {
             assertEquals("wrong locked mode", isLib, (boolean) br.getCircuit().getAttributes().get(Keys.LOCKED_MODE));
 
             try {
-                for (VisualElement el : br.getCircuit().getElements())
-                    if (el.equalsDescription(TestCaseElement.TESTCASEDESCRIPTION)) {
-                        testCasesInFiles++;
+                for (Circuit.TestCase tc : br.getCircuit().getTestCases()) {
+                    testCasesInFiles++;
 
-                        String label = el.getElementAttributes().getLabel();
-                        TestCaseDescription td = el.getElementAttributes().get(Keys.TESTDATA);
+                    String label = tc.getLabel();
+                    TestCaseDescription td = tc.getTestCaseDescription();
 
-                        Model model = new ModelCreator(br.getCircuit(), br.getLibrary()).createModel(false);
-                        ErrorDetector ed = new ErrorDetector();
-                        model.addObserver(ed);
-                        try {
-                            TestExecutor tr = new TestExecutor(td).create(model);
+                    Model model = new ModelCreator(br.getCircuit(), br.getLibrary()).createModel(false);
+                    ErrorDetector ed = new ErrorDetector();
+                    model.addObserver(ed);
+                    try {
+                        TestExecutor tr = new TestExecutor(td).create(model);
 
-                            if (label.contains("Failing"))
-                                assertFalse(dig.getName() + ":" + label, tr.allPassed());
-                            else
-                                assertTrue(dig.getName() + ":" + label, tr.allPassed());
+                        if (label.contains("Failing"))
+                            assertFalse(dig.getName() + ":" + label, tr.allPassed());
+                        else
+                            assertTrue(dig.getName() + ":" + label, tr.allPassed());
 
-                        } finally {
-                            model.close();
-                        }
-                        ed.check();
+                    } finally {
+                        model.close();
                     }
+                    ed.check();
+                }
             } catch (Exception e) {
                 if (shouldFail) {
                     return;
@@ -114,8 +112,15 @@ public class TestExamples extends TestCase {
             br.close();
         }
 
-        if (br.getCircuit().getAttributes().get(Keys.IS_GENERIC))
-            checkGeneric(br.getCircuit(), br.getLibrary());
+        if (br.getCircuit().
+
+                getAttributes().
+
+                get(Keys.IS_GENERIC))
+
+            checkGeneric(br.getCircuit(), br.
+
+                    getLibrary());
     }
 
     private void checkGeneric(Circuit circuit, ElementLibrary library) throws NodeException, ElementNotFoundException, PinException {