diff --git a/test/unflattenTreeWIP.spec.js b/test/unflattenTreeWIP.spec.js
new file mode 100644
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+++ b/test/unflattenTreeWIP.spec.js
@@ -0,0 +1,129 @@
+import chai from "chai"
+import * as F from "../src"
+import _ from "lodash/fp"
+
+chai.expect()
+const expect = chai.expect
+
+describe("unflattenTree", () => {
+  let flat = {
+    Field1: { type: "text1" },
+    "Field2/Field2A/Field2A1": { type: "text2" },
+    "Field2/Field2A/Field2A2": { type: "text3" },
+    "Field2/Field2A/Field2A3/Field2A3a": { type: "text4" },
+    "Field2/Field2B": { type: "text5" },
+    "Field2/Field2C": { type: "text6" },
+    Field2: { type: "group" },
+  }
+
+  let unflatten = (lookup, createNode, encoder, _flat) => {
+    // Clone because this method mutates `flat` (because `treeValue` is mutated in createNode)
+    let flat = _.cloneDeep(_flat)
+    return F.reduceIndexed(
+      (result, node, key) => {
+        let path = encoder.decode(key)
+        // prefixes to check
+        let prefixes = F.prefixes(path)
+        // ensure/create path
+        _.each((prefix) => {
+          // if prefix doesn't exist, create it
+          // if Not already in result
+          if (!lookup(prefix, result)) {
+            // check tree
+            let treeValue = flat[encoder.encode(prefix)]
+            let defaultNode = {}
+            let parent = lookup(_.dropRight(1, prefix), result) || result
+            createNode(prefix, treeValue || defaultNode, result, parent)
+          }
+        }, prefixes)
+
+        return result
+      },
+      {},
+      flat
+    )
+  }
+
+  let keyIteratee = (x) => (val, k) => k == x
+
+  it("simple nested object", () => {
+    let lookup = F.treeLookup((x) => x, keyIteratee)
+    let createNode = F.setOn
+    let result = unflatten(lookup, createNode, F.slashEncoder, flat)
+    expect(result).to.deep.equal({
+      Field1: { type: "text1" },
+      Field2: {
+        type: "group",
+        Field2A: {
+          Field2A1: { type: "text2" },
+          Field2A2: { type: "text3" },
+          Field2A3: { Field2A3a: { type: "text4" } },
+        },
+        Field2B: { type: "text5" },
+        Field2C: { type: "text6" },
+      },
+    })
+  })
+  it("json schema style 'properties' objects", () => {
+    let lookup = F.treeLookup((x) => x.properties, keyIteratee)
+    let createNode = (prefix, val, tree, parent) => {
+      parent.properties = parent.properties || {}
+      parent.properties[_.last(prefix)] = val
+    }
+    let result2 = unflatten(lookup, createNode, F.slashEncoder, flat)
+    expect(result2).to.deep.equal({
+      properties: {
+        Field1: { type: "text1" },
+        Field2: {
+          type: "group",
+          properties: {
+            Field2A: {
+              properties: {
+                Field2A1: { type: "text2" },
+                Field2A2: { type: "text3" },
+                Field2A3: { properties: { Field2A3a: { type: "text4" } } },
+              },
+            },
+            Field2B: { type: "text5" },
+            Field2C: { type: "text6" },
+          },
+        },
+      },
+    })
+  })
+  it("contexture children objs", () => {
+    let lookup = F.treeLookup(
+      (x) => x.children,
+      (key) => ({ key })
+    )
+    let createNode = (prefix, val, tree, parent) => {
+      parent.children = parent.children || []
+      parent.children.push({ key: _.last(prefix), ...val })
+    }
+    let result3 = unflatten(lookup, createNode, F.slashEncoder, flat)
+    expect(result3).to.deep.equal({
+      children: [
+        { key: "Field1", type: "text1" },
+        {
+          key: "Field2",
+          type: "group",
+          children: [
+            {
+              key: "Field2A",
+              children: [
+                { key: "Field2A1", type: "text2" },
+                { key: "Field2A2", type: "text3" },
+                {
+                  key: "Field2A3",
+                  children: [{ key: "Field2A3a", type: "text4" }],
+                },
+              ],
+            },
+            { key: "Field2B", type: "text5" },
+            { key: "Field2C", type: "text6" },
+          ],
+        },
+      ],
+    })
+  })
+})