build: add build of empty tests

Add tests to the build.

Change-Id: Ic12b5eee708a3ec8e16d997f2a7d18adec2c779d
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/Makefile.am b/Makefile.am
index 0bc2b36..d37ef87 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -21,3 +21,5 @@
 	$(PHOSPHOR_LOGGING_CFLAGS) \
 	$(LIBIPMID_CFLAGS) \
 	-flto
+
+SUBDIRS = . test
diff --git a/configure.ac b/configure.ac
index 26e8956..3da6d4b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -34,6 +34,75 @@
 # Checks for library functions.
 LT_INIT # Required for systemd linking
 
+# Make it possible for users to choose if they want test support
+# explicitly or not at all
+AC_ARG_ENABLE([tests], AC_HELP_STRING([--disable-tests],
+                                      [Build test cases]))
+
+# Check/set gtest specific functions.
+AS_IF([test "x$enable_tests" != "xno"], [
+    PKG_CHECK_MODULES([GTEST], [gtest], [], [true])
+    PKG_CHECK_MODULES([GMOCK], [gmock], [], [true])
+    AX_PTHREAD
+
+    AX_SAVE_FLAGS_WITH_PREFIX(OLD, [CPPFLAGS])
+    AX_APPEND_COMPILE_FLAGS([$GTEST_CFLAGS], [CPPFLAGS])
+    AC_LANG_PUSH([C++])
+    AC_CHECK_HEADERS([gtest/gtest.h], [
+        AS_IF([test "x$GTEST_CFLAGS" = "x"], [
+            AS_IF([test "x$PTHREAD_CFLAGS" = "x"], [
+                AX_APPEND_COMPILE_FLAGS(["-DGTEST_HAS_PTHREAD=0"], [GTEST_CFLAGS])
+            ], [
+                AX_APPEND_COMPILE_FLAGS(["-DGTEST_HAS_PTHREAD=1"], [GTEST_CFLAGS])
+                AX_APPEND_COMPILE_FLAGS([$PTHREAD_CFLAGS], [GTEST_CFLAGS])
+            ])
+        ])
+    ], [
+        AS_IF([test "x$enable_tests" = "xyes"], [
+            AC_MSG_ERROR([Testing enabled but could not find gtest/gtest.h])
+        ])
+    ])
+    AC_LANG_POP([C++])
+    AX_RESTORE_FLAGS_WITH_PREFIX(OLD, [CPPFLAGS])
+
+    AX_SAVE_FLAGS_WITH_PREFIX(OLD, [CPPFLAGS])
+    AX_APPEND_COMPILE_FLAGS([$GMOCK_CFLAGS], [CPPFLAGS])
+    AC_LANG_PUSH([C++])
+    AC_CHECK_HEADERS([gmock/gmock.h], [], [
+        AS_IF([test "x$enable_tests" = "xyes"], [
+            AC_MSG_ERROR([Testing enabled but could not find gmock/gmock.h])
+        ])
+    ])
+    AC_LANG_POP([C++])
+    AX_RESTORE_FLAGS_WITH_PREFIX(OLD, [CPPFLAGS])
+
+    AX_SAVE_FLAGS_WITH_PREFIX(OLD, [LDFLAGS])
+    AX_APPEND_COMPILE_FLAGS([$GTEST_LIBS], [LDFLAGS])
+    AC_CHECK_LIB([gtest], [main], [
+        AS_IF([test "x$GTEST_LIBS" = "x"], [
+            AX_APPEND_COMPILE_FLAGS([-lgtest], [GTEST_LIBS])
+        ])
+    ], [
+        AS_IF([test "x$enable_tests" = "xyes"], [
+            AC_MSG_ERROR([Testing enabled but couldn't find gtest libs])
+        ])
+    ])
+    AX_RESTORE_FLAGS_WITH_PREFIX(OLD, [LDFLAGS])
+
+    AX_SAVE_FLAGS_WITH_PREFIX(OLD, [LDFLAGS])
+    AX_APPEND_COMPILE_FLAGS([$GMOCK_LIBS], [LDFLAGS])
+    AC_CHECK_LIB([gmock], [main], [
+        AS_IF([test "x$GMOCK_LIBS" = "x"], [
+            AX_APPEND_COMPILE_FLAGS([-lgmock], [GMOCK_LIBS])
+        ])
+    ], [
+        AS_IF([test "x$enable_tests" = "xyes"], [
+            AC_MSG_ERROR([Testing enabled but couldn't find gmock libs])
+        ])
+    ])
+    AX_RESTORE_FLAGS_WITH_PREFIX(OLD, [LDFLAGS])
+])
+
 PKG_PROG_PKG_CONFIG
 AC_ARG_WITH([systemdsystemunitdir],
      [AS_HELP_STRING([--with-systemdsystemunitdir=DIR], [Directory for systemd service files])],,
@@ -51,5 +120,5 @@
 AM_CONDITIONAL([HAVE_SYSTEMD], [test "x$with_systemdsystemunitdir" != "xno"])
 
 # Create configured output
-AC_CONFIG_FILES([Makefile])
+AC_CONFIG_FILES([Makefile test/Makefile])
 AC_OUTPUT
diff --git a/test/Makefile.am b/test/Makefile.am
new file mode 100644
index 0000000..3a400d5
--- /dev/null
+++ b/test/Makefile.am
@@ -0,0 +1,4 @@
+
+
+check_PROGRAMS =
+TESTS = $(check_PROGRAMS)