bm_instance: Create a new handler

This OEM handler will get properties from tmpfs to serve over IPMI.

Tested:
~# cat /run/bm-instance/asset-tag
12345
~# ipmitool raw 0x2e 0x32 0x79 0x2b 0x00 0x17 0x00
 79 2b 00 17 05 31 32 33 34 35
...
...
(Verified this works for all 7 sub commands)

Signed-off-by: Brandon Kim <brandonkim@google.com>
Change-Id: I191b6f4994d91ada49a3332a8e93a3a305561904
diff --git a/test/bm_instance_unittest.cpp b/test/bm_instance_unittest.cpp
new file mode 100644
index 0000000..2c603c4
--- /dev/null
+++ b/test/bm_instance_unittest.cpp
@@ -0,0 +1,76 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "bm_instance.hpp"
+#include "commands.hpp"
+#include "handler_mock.hpp"
+#include "helper.hpp"
+
+#include <string>
+#include <vector>
+
+#include <gtest/gtest.h>
+
+namespace google
+{
+namespace ipmi
+{
+
+using testing::_;
+using ::testing::Return;
+using ::testing::StrEq;
+
+TEST(GetBMInstancePropertyTest, InvalidRequestSize)
+{
+    std::vector<uint8_t> request = {};
+
+    HandlerMock hMock;
+    EXPECT_EQ(::ipmi::responseReqDataLenInvalid(),
+              getBMInstanceProperty(request, &hMock));
+}
+
+TEST(GetBMInstancePropertyTest, InvalidCommand)
+{
+    std::vector<uint8_t> request = {1};
+    std::string expectedOutput(64, 'a');
+
+    HandlerMock hMock;
+    EXPECT_CALL(hMock, getBMInstanceProperty(1))
+        .WillOnce(Return(expectedOutput));
+    EXPECT_EQ(::ipmi::responseInvalidCommand(),
+              getBMInstanceProperty(request, &hMock));
+}
+
+TEST(GetBMInstancePropertyTest, ValidRequest)
+{
+    std::vector<uint8_t> request = {2};
+    std::string expectedOutput = "asdf";
+
+    HandlerMock hMock;
+    EXPECT_CALL(hMock, getBMInstanceProperty(2))
+        .WillOnce(Return(expectedOutput));
+
+    auto reply = getBMInstanceProperty(request, &hMock);
+    auto result = ValidateReply(reply);
+    auto& data = result.second;
+
+    EXPECT_EQ(sizeof(struct BMInstancePropertyReply) + expectedOutput.size(),
+              data.size());
+    EXPECT_EQ(SysOEMCommands::SysGetBMInstanceProperty, result.first);
+    EXPECT_THAT(std::string(data.begin() + 1, data.end()),
+                StrEq(expectedOutput));
+}
+
+} // namespace ipmi
+} // namespace google