diff --git a/buffet/commands/command_manager_unittest.cc b/buffet/commands/command_manager_unittest.cc
index 1a0bfec..65241fe 100644
--- a/buffet/commands/command_manager_unittest.cc
+++ b/buffet/commands/command_manager_unittest.cc
@@ -2,11 +2,107 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <base/file_util.h>
+#include <base/json/json_writer.h>
 #include <gtest/gtest.h>
 
 #include "buffet/commands/command_manager.h"
+#include "buffet/commands/unittest_utils.h"
+
+using buffet::unittests::CreateDictionaryValue;
+
+static base::FilePath SaveJsonToTempFile(const base::DictionaryValue& dict) {
+  std::string json;
+  base::JSONWriter::Write(&dict, &json);
+  base::FilePath temp_file;
+  base::CreateTemporaryFile(&temp_file);
+  base::WriteFile(temp_file, json.data(), static_cast<int>(json.size()));
+  return temp_file;
+}
 
 TEST(CommandManager, Empty) {
   buffet::CommandManager manager;
   EXPECT_TRUE(manager.GetCommandDictionary().IsEmpty());
 }
+
+TEST(CommandManager, LoadBaseCommandsJSON) {
+  buffet::CommandManager manager;
+  auto json = CreateDictionaryValue(R"({
+    'base': {
+      'reboot': {
+        'parameters': {'delay': 'integer'}
+      },
+      'shutdown': {
+        'parameters': {}
+      }
+    }
+  })");
+  EXPECT_TRUE(manager.LoadBaseCommands(*json, nullptr));
+}
+
+TEST(CommandManager, LoadBaseCommandsFile) {
+  buffet::CommandManager manager;
+  auto json = CreateDictionaryValue(R"({
+    'base': {
+      'reboot': {
+        'parameters': {'delay': 'integer'}
+      },
+      'shutdown': {
+        'parameters': {}
+      }
+    }
+  })");
+  base::FilePath temp_file = SaveJsonToTempFile(*json);
+  EXPECT_TRUE(manager.LoadBaseCommands(temp_file, nullptr));
+  base::DeleteFile(temp_file, false);
+}
+
+TEST(CommandManager, LoadCommandsJSON) {
+  buffet::CommandManager manager;
+  auto json = CreateDictionaryValue(R"({
+    'robot': {
+      '_jump': {
+        'parameters': {'height': 'integer'}
+      },
+      '_speak': {
+        'parameters': {'phrase': 'string'}
+      }
+    }
+  })");
+  EXPECT_TRUE(manager.LoadCommands(*json, "category", nullptr));
+}
+
+TEST(CommandManager, LoadCommandsFile) {
+  buffet::CommandManager manager;
+  // Load some standard command definitions first.
+  auto json = CreateDictionaryValue(R"({
+    'base': {
+      'reboot': {
+        'parameters': {'delay': 'integer'}
+      },
+      'shutdown': {
+        'parameters': {}
+      }
+    }
+  })");
+  manager.LoadBaseCommands(*json, nullptr);
+  // Load device-supported commands.
+  json = CreateDictionaryValue(R"({
+    'base': {
+      'reboot': {
+        'parameters': {'delay': 'integer'}
+      }
+    },
+    'robot': {
+      '_jump': {
+        'parameters': {'height': 'integer'}
+      }
+    }
+  })");
+  base::FilePath temp_file = SaveJsonToTempFile(*json);
+  EXPECT_TRUE(manager.LoadCommands(temp_file, nullptr));
+  base::DeleteFile(temp_file, false);
+  EXPECT_EQ(2, manager.GetCommandDictionary().GetSize());
+  EXPECT_NE(nullptr, manager.GetCommandDictionary().FindCommand("base.reboot"));
+  EXPECT_NE(nullptr, manager.GetCommandDictionary().FindCommand("robot._jump"));
+}