Plan picked path callbacks in app core

tests/app_core/document_platform_io_tests.cpp

@@ -0,0 +1,28 @@
+#include "app_core/document_platform_io.h"
+#include "test_harness.h"
+
+namespace {
+
+void picked_path_ignores_empty_path(pp::tests::Harness& harness)
+{
+    PP_EXPECT(
+        harness,
+        pp::app::plan_picked_path("") == pp::app::PickedPathAction::ignore_empty_path);
+}
+
+void picked_path_invokes_callback_for_nonempty_path(pp::tests::Harness& harness)
+{
+    PP_EXPECT(
+        harness,
+        pp::app::plan_picked_path("D:/Paint/demo.ppi") == pp::app::PickedPathAction::invoke_callback);
+}
+
+}
+
+int main()
+{
+    pp::tests::Harness harness;
+    harness.run("picked path ignores empty path", picked_path_ignores_empty_path);
+    harness.run("picked path invokes callback for nonempty path", picked_path_invokes_callback_for_nonempty_path);
+    return harness.finish();
+}