test: message: read: add test for unix_fd

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I602b3d2d44dbd74916aa73d018b37ff0cafb210d
diff --git a/test/message/read.cpp b/test/message/read.cpp
index 42df2af..7944330 100644
--- a/test/message/read.cpp
+++ b/test/message/read.cpp
@@ -159,6 +159,15 @@
     EXPECT_EQ(s, ret.str);
 }
 
+TEST_F(ReadTest, UnixFd)
+{
+    const int fd = 42;
+    expect_basic<int>(SD_BUS_TYPE_UNIX_FD, fd);
+    sdbusplus::message::unix_fd ret;
+    new_message().read(ret);
+    EXPECT_EQ(fd, ret);
+}
+
 TEST_F(ReadTest, CombinedBasic)
 {
     const double a = 2.2;