diff --git a/buffet/states/state_manager_unittest.cc b/buffet/states/state_manager_unittest.cc
new file mode 100644
index 0000000..1ce130d
--- /dev/null
+++ b/buffet/states/state_manager_unittest.cc
@@ -0,0 +1,130 @@
+// Copyright 2014 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+
+#include <base/values.h>
+#include <gtest/gtest.h>
+
+#include "buffet/commands/schema_constants.h"
+#include "buffet/commands/unittest_utils.h"
+#include "buffet/states/error_codes.h"
+#include "buffet/states/state_manager.h"
+
+using buffet::unittests::CreateDictionaryValue;
+using buffet::unittests::ValueToString;
+
+namespace buffet {
+
+namespace {
+std::unique_ptr<base::DictionaryValue> GetTestSchema() {
+  return CreateDictionaryValue(R"({
+    'base': {
+      'manufacturer':'string',
+      'serialNumber':'string'
+    },
+    'terminator': {
+      'target':'string'
+    }
+  })");
+}
+
+std::unique_ptr<base::DictionaryValue> GetTestValues() {
+  return CreateDictionaryValue(R"({
+    'base': {
+      'manufacturer':'Skynet',
+      'serialNumber':'T1000'
+    }
+  })");
+}
+}  // anonymous namespace
+
+class StateManagerTest : public ::testing::Test {
+ public:
+  void SetUp() override {
+    mgr_.reset(new StateManager);
+    LoadStateDefinition(GetTestSchema().get(), "default", nullptr);
+    ASSERT_TRUE(mgr_->LoadStateDefaults(*GetTestValues().get(), nullptr));
+  }
+  void TearDown() override {
+    mgr_.reset();
+  }
+
+  void LoadStateDefinition(const base::DictionaryValue* json,
+                           const std::string& category,
+                           chromeos::ErrorPtr* error) {
+    ASSERT_TRUE(mgr_->LoadStateDefinition(*json, category, error));
+  }
+
+  std::unique_ptr<StateManager> mgr_;
+};
+
+TEST(StateManager, Empty) {
+  StateManager manager;
+  EXPECT_TRUE(manager.GetCategories().empty());
+}
+
+TEST_F(StateManagerTest, Initialized) {
+  EXPECT_EQ(std::set<std::string>{"default"}, mgr_->GetCategories());
+  EXPECT_EQ("{'base':{'manufacturer':'Skynet','serialNumber':'T1000'},"
+            "'terminator':{'target':''}}",
+            ValueToString(mgr_->GetStateValuesAsJson(nullptr).get()));
+}
+
+TEST_F(StateManagerTest, LoadStateDefinition) {
+  auto dict = CreateDictionaryValue(R"({
+    'power': {
+      'battery_level':'integer'
+    }
+  })");
+  LoadStateDefinition(dict.get(), "powerd", nullptr);
+  EXPECT_EQ((std::set<std::string>{"default", "powerd"}),
+            mgr_->GetCategories());
+  EXPECT_EQ("{'base':{'manufacturer':'Skynet','serialNumber':'T1000'},"
+            "'power':{'battery_level':0},"
+            "'terminator':{'target':''}}",
+            ValueToString(mgr_->GetStateValuesAsJson(nullptr).get()));
+}
+
+TEST_F(StateManagerTest, SetPropertyValue) {
+  ASSERT_TRUE(mgr_->SetPropertyValue("terminator.target",
+                                     std::string{"John Connor"}, nullptr));
+  EXPECT_EQ("{'base':{'manufacturer':'Skynet','serialNumber':'T1000'},"
+            "'terminator':{'target':'John Connor'}}",
+            ValueToString(mgr_->GetStateValuesAsJson(nullptr).get()));
+}
+
+TEST_F(StateManagerTest, SetPropertyValue_Error_NoName) {
+  chromeos::ErrorPtr error;
+  ASSERT_FALSE(mgr_->SetPropertyValue("", int{0}, &error));
+  EXPECT_EQ(errors::state::kDomain, error->GetDomain());
+  EXPECT_EQ(errors::state::kPropertyNameMissing, error->GetCode());
+  EXPECT_EQ("Property name is missing", error->GetMessage());
+}
+
+TEST_F(StateManagerTest, SetPropertyValue_Error_NoPackage) {
+  chromeos::ErrorPtr error;
+  ASSERT_FALSE(mgr_->SetPropertyValue("target", int{0}, &error));
+  EXPECT_EQ(errors::state::kDomain, error->GetDomain());
+  EXPECT_EQ(errors::state::kPackageNameMissing, error->GetCode());
+  EXPECT_EQ("Package name is missing in the property name",
+            error->GetMessage());
+}
+
+TEST_F(StateManagerTest, SetPropertyValue_Error_UnknownPackage) {
+  chromeos::ErrorPtr error;
+  ASSERT_FALSE(mgr_->SetPropertyValue("power.level", int{0}, &error));
+  EXPECT_EQ(errors::state::kDomain, error->GetDomain());
+  EXPECT_EQ(errors::state::kPropertyNotDefined, error->GetCode());
+  EXPECT_EQ("Unknown state property package 'power'", error->GetMessage());
+}
+
+TEST_F(StateManagerTest, SetPropertyValue_Error_UnknownProperty) {
+  chromeos::ErrorPtr error;
+  ASSERT_FALSE(mgr_->SetPropertyValue("base.level", int{0}, &error));
+  EXPECT_EQ(errors::state::kDomain, error->GetDomain());
+  EXPECT_EQ(errors::state::kPropertyNotDefined, error->GetCode());
+  EXPECT_EQ("State property 'base.level' is not defined", error->GetMessage());
+}
+
+}  // namespace buffet