gpio-presence: add test cases for GPIO comparisons

Add test cases for the DevicePresence class, where GPIO state
is cached in a map and then decisions about device presence are
made.  Add coverage of many GPIO + cache states for the determination.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I3a11c174d6a0a8b92c446dde3e0345b195a67a9c
diff --git a/test/meson.build b/test/meson.build
index 5282b07..20b413b 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -75,3 +75,15 @@
         dependencies: [gtest, phosphor_logging_dep, sdbusplus],
     ),
 )
+
+test(
+    'test_gpio_presence_state',
+    executable(
+        'test_gpio_presence_state',
+        'test_gpio_presence_state.cpp',
+        cpp_args: test_boost_args,
+        include_directories: test_include_dir,
+        dependencies: [boost, gtest, gmock, phosphor_logging_dep, libgpio_dep],
+        link_with: gpio_presence_lib,
+    ),
+)