test: Make sure mocks compile

This makes sure we don't accidentally change our interface without
updating the mock.

Change-Id: I50c6827e637167f1223d91f724b99ef8a24b107f
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/.gitignore b/.gitignore
index 9154cb2..15f8350 100644
--- a/.gitignore
+++ b/.gitignore
@@ -46,4 +46,5 @@
 /test/event
 /test/handle
 /test/internal/fd
+/test/mocks
 /test/utility/aspeed
diff --git a/test/Makefile.am b/test/Makefile.am
index 28bab29..103010d 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -27,6 +27,11 @@
 internal_fd_CPPFLAGS = $(gtest_cppflags)
 internal_fd_LDADD = $(gtest_ldadd)
 
+check_PROGRAMS += mocks
+mocks_SOURCES = mocks.cpp
+mocks_CPPFLAGS = $(gtest_cppflags)
+mocks_LDADD = $(gtest_ldadd)
+
 check_PROGRAMS += utility/aspeed
 utility_aspeed_SOURCES = utility/aspeed.cpp
 utility_aspeed_CPPFLAGS = $(gtest_cppflags)
diff --git a/test/mocks.cpp b/test/mocks.cpp
new file mode 100644
index 0000000..2bc1f61
--- /dev/null
+++ b/test/mocks.cpp
@@ -0,0 +1,14 @@
+#include <gpioplus/test/handle.hpp>
+
+namespace gpioplus
+{
+namespace
+{
+
+TEST(Mocks, Compile)
+{
+    test::HandleMock handle;
+}
+
+} // namespace
+} // namespace gpioplus