Improve GAppInfo test coverage

gio/tests/appinfo-test.desktop

@@ -1,13 +1,17 @@
 [Desktop Entry]
 Type=Application
+GenericName=generic-appinfo-test
 Name=appinfo-test
 Name[de]=appinfo-test-de
 X-GNOME-FullName=example
 X-GNOME-FullName[de]=Beispiel
 Comment=GAppInfo example
 Comment[de]=GAppInfo Beispiel
-Exec=./appinfo-test --option
-Icon=testicon
+Exec=./appinfo-test --option %U %i --name %c --filename %k %m %%
+Icon=testicon.svg
+Terminal=true
 StartupNotify=true
 StartupWMClass=appinfo-class
 MimeType=image/png;image/jpeg;
+Keywords=keyword1;test keyword;
+Categories=GNOME;GTK;