diff --git a/.gitignore b/.gitignore
index e67f88e8..dcf450f2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -32,4 +32,6 @@ __pycache__
 repro
 java_test/test.parquet
 java_test/test.arrow
-java_test/simulation*
\ No newline at end of file
+java_test/simulation*
+.idea
+.calva
diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 00000000..8f2b7113
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,3 @@
+{
+    "java.compile.nullAnalysis.mode": "disabled"
+}
\ No newline at end of file
diff --git a/java_test/java/jtest/ConfigTest.java b/java_test/java/jtest/ConfigTest.java
new file mode 100644
index 00000000..7b197458
--- /dev/null
+++ b/java_test/java/jtest/ConfigTest.java
@@ -0,0 +1,51 @@
+package jtest;
+
+import com.oracle.labs.mlrg.olcut.config.Configurable;
+import com.oracle.labs.mlrg.olcut.config.ConfigurationData;
+import com.oracle.labs.mlrg.olcut.config.ConfigurationManager;
+import com.oracle.labs.mlrg.olcut.config.DescribeConfigurable;
+import com.oracle.labs.mlrg.olcut.config.property.Property;
+import com.oracle.labs.mlrg.olcut.config.property.SimpleProperty;
+import org.tribuo.classification.dtree.CARTClassificationTrainer;
+import org.tribuo.classification.dtree.impurity.Entropy;
+import org.tribuo.classification.dtree.impurity.GiniIndex;
+import org.tribuo.classification.dtree.impurity.LabelImpurity;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.SortedMap;
+
+public class ConfigTest {
+
+    public static final  void describe () {
+
+    }
+    public static void main(String[] args) {
+
+        Class clazz = CARTClassificationTrainer.class;
+
+        SortedMap<String, DescribeConfigurable.FieldInfo> generateFieldInfos = DescribeConfigurable.generateFieldInfo(clazz);
+
+
+        //System.out.println("DescribeConfigurable.generateFieldInfo(CARTClassificationTrainer.class) = " + generateFieldInfo);
+        ConfigurationManager cm = new ConfigurationManager();
+        DescribeConfigurable dc = new DescribeConfigurable();
+
+
+
+        Map<String, Property> properties = Map.of(
+                "maxDepth", new SimpleProperty("20"),
+                "minImpurityDecrease",new SimpleProperty("0.5"),
+                "impurity",new SimpleProperty("entropy")
+        );
+        ConfigurationData configData0 = new ConfigurationData("entropy", Entropy.class.getName());
+        cm.addConfiguration(configData0);
+        ConfigurationData configData1 = new ConfigurationData(CARTClassificationTrainer.class.getName(), clazz.getName(),properties);
+
+        cm.addConfiguration(configData1);
+        Configurable lookup = cm.lookup(clazz.getName());
+        System.out.println(lookup);
+
+
+    }
+}
diff --git a/test/tech/v3/dataset/categorical_test.clj b/test/tech/v3/dataset/categorical_test.clj
index 851ea030..87ce9fef 100644
--- a/test/tech/v3/dataset/categorical_test.clj
+++ b/test/tech/v3/dataset/categorical_test.clj
@@ -87,3 +87,62 @@
           (get :y)
           distinct
           set))))
+
+
+(defn- =-invert-cat [target-1 target-2
+                         lookup-one lookup-two
+                         result-datatype
+                      expected-result
+                      ]
+  (let [ds (ds/->dataset {:target [target-1 target-2]})
+        inverted
+        (ds-cat/invert-categorical-map ds
+                                       {:lookup-table {:one lookup-one
+                                                       :two lookup-two},
+                                        :src-column :target,
+                                        :result-datatype result-datatype})
+        inverted-target (-> inverted :target)]
+    (= expected-result inverted-target)))
+    ;(format "expected %s,  found: %s" expected-result) (seq inverted-target)))
+
+(deftest invert-cat--works
+  (is
+   (=-invert-cat 1 2
+                  1 2
+                  :int
+                  [:one :two]))
+  ; TODO - should pass ?
+  (is (=-invert-cat 1.0 2.0
+                     1 2
+                     :int
+                     [:one :two]))
+  
+  ; TODO - should pass ?
+  (is (=-invert-cat 1.99999 2.99999
+                     1 2
+                     :int
+                     [:one :two]))
+  
+  ; TODO - should pass ?
+  (is (=-invert-cat 1.2 1.3
+                     1 2
+                     :int
+                     [:one :one])))
+
+(deftest invert-cat--throws
+  (is (thrown? Exception
+                (=-invert-cat 1 2
+                               4 5
+                               :int
+                               [:one :two])))
+;; => Execution error at tech.v3.dataset.categorical/invert-categorical-map$fn (categorical.clj:177).
+;;    Unable to find src value for numeric value 1
+  
+  (is (thrown? Exception
+       (=-invert-cat 1 2
+                      1.0 2.0
+                      :int
+                      [:one :two]))))
+;; => Execution error at tech.v3.dataset.categorical/invert-categorical-map$fn (categorical.clj:177).
+;;    Unable to find src value for numeric value 1
+