diff --git a/build.mill b/build.mill
index df87195..7204e7b 100644
--- a/build.mill
+++ b/build.mill
@@ -5,3 +5,7 @@ object core extends ScalaModule:
   def scalaVersion = "3.7.2"
   def scalacOptions = Seq("-Wunused:all")
   def mvnDeps = Seq(mvn"dev.zio::zio-json:0.7.44")
+
+  object test extends ScalaTests with TestModule.Utest:
+    def utestVersion = "0.9.0"
+
diff --git a/core/test/src/scalive/LiveViewSpec.scala b/core/test/src/scalive/LiveViewSpec.scala
new file mode 100644
index 0000000..120e9b9
--- /dev/null
+++ b/core/test/src/scalive/LiveViewSpec.scala
@@ -0,0 +1,157 @@
+package scalive
+
+import utest.*
+import zio.json.*
+import zio.json.ast.Json
+
+object LiveViewSpec extends TestSuite:
+
+  final case class TestModel(
+      title: String = "title value",
+      bool: Boolean = false,
+      nestedTitle: String = "nested title value"
+  )
+
+  def assertEqualsJson(actual: Json, expected: Json) =
+    assert(actual.toJsonPretty == expected.toJsonPretty)
+
+  val emptyDiff = Json.Obj("diff" -> Json.Obj.empty)
+
+  val tests = Tests {
+
+    test("Static only") {
+      val lv =
+        LiveViewRenderer.render(
+          new LiveView[Unit]:
+            val view: HtmlTag[Unit] =
+              div("Static string")
+          ,
+          ()
+        )
+      test("init") {
+        assertEqualsJson(
+          lv.buildInitJson,
+          Json.Obj(
+            "s" -> Json.Arr(Json.Str("<div>Static string</div>"))
+          )
+        )
+      }
+      test("diff") {
+        assertEqualsJson(lv.buildDiffJson, emptyDiff)
+      }
+    }
+
+    test("Dynamic string") {
+      val lv =
+        LiveViewRenderer.render(
+          new LiveView[TestModel]:
+            val view: HtmlTag[TestModel] =
+              div(model(_.title))
+          ,
+          TestModel()
+        )
+      test("init") {
+        assertEqualsJson(
+          lv.buildInitJson,
+          Json
+            .Obj(
+              "s" -> Json.Arr(Json.Str("<div>"), Json.Str("</div>")),
+              "0" -> Json.Str("title value")
+            )
+        )
+      }
+      test("diff no update") {
+        assertEqualsJson(lv.buildDiffJson, emptyDiff)
+      }
+      test("diff with update") {
+        lv.update(TestModel(title = "title updated"))
+        assertEqualsJson(
+          lv.buildDiffJson,
+          Json.Obj(
+            "diff" -> Json.Obj("0" -> Json.Str("title updated"))
+          )
+        )
+      }
+      test("diff with update and no change") {
+        lv.update(TestModel(title = "title updated"))
+        lv.update(TestModel(title = "title updated"))
+        assertEqualsJson(lv.buildDiffJson, emptyDiff)
+      }
+    }
+
+    test("when mod") {
+      val lv =
+        LiveViewRenderer.render(
+          new LiveView[TestModel]:
+            val view: HtmlTag[TestModel] =
+              div(
+                model.when(_.bool)(
+                  div("static string", model(_.nestedTitle))
+                )
+              )
+          ,
+          TestModel()
+        )
+      test("init") {
+        assertEqualsJson(
+          lv.buildInitJson,
+          Json
+            .Obj(
+              "s" -> Json.Arr(Json.Str("<div>"), Json.Str("</div>")),
+              "0" -> Json.Bool(false)
+            )
+        )
+      }
+      test("diff no update") {
+        assertEqualsJson(lv.buildDiffJson, emptyDiff)
+      }
+      test("diff with unrelated update") {
+        lv.update(TestModel(title = "title updated"))
+        assertEqualsJson(lv.buildDiffJson, emptyDiff)
+      }
+      test("diff when true") {
+        lv.update(TestModel(bool = true))
+        assertEqualsJson(
+          lv.buildDiffJson,
+          Json.Obj(
+            "diff" -> Json.Obj(
+              "0" ->
+                Json
+                  .Obj(
+                    "s" -> Json
+                      .Arr(Json.Str("<div>static string"), Json.Str("</div>")),
+                    "0" -> Json.Str("nested title value")
+                  )
+            )
+          )
+        )
+      }
+      test("diff when nested change") {
+        lv.update(TestModel(bool = true))
+        lv.update(TestModel(bool = true, nestedTitle = "nested title updated"))
+        assertEqualsJson(
+          lv.buildDiffJson,
+          Json.Obj(
+            "diff" -> Json.Obj(
+              "0" ->
+                Json
+                  .Obj(
+                    "0" -> Json.Str("nested title updated")
+                  )
+            )
+          )
+        )
+      }
+    }
+  }
+
+object TestLiveView extends LiveView[MyModel]:
+  val view: HtmlTag[MyModel] =
+    div(
+      div("Static string 1"),
+      model(_.title),
+      div("Static string 2"),
+      model.when(_.bool)(
+        div("maybe rendered", model(_.nestedTitle))
+      )
+    )