Make unit tests on native possible

platformio.ini

@@ -11,13 +11,14 @@
 data_dir = data/build_gz
 
 [env]
+
+
+[btclock_base]
 platform = https://github.com/platformio/platform-espressif32.git
 framework =  arduino, espidf
 monitor_speed = 115200
 monitor_filters = esp32_exception_decoder, colorize
 board_build.filesystem = littlefs
-
-[btclock_base]
 extra_scripts = post:scripts/extra_script.py
 build_flags =
   !python scripts/git_rev.py
@@ -84,4 +85,14 @@ build_flags =
     -D MCP2_A1_PIN=10
     -D MCP2_A2_PIN=14
 build_unflags = 
-  ${btclock_base.build_unflags}
+  ${btclock_base.build_unflags}
+
+[env:native_test_only]
+platform = native
+test_framework = unity
+build_flags =
+    ${btclock_base.build_flags}
+    -D MCP_INT_PIN=8
+    -D NEOPIXEL_PIN=34
+    -D NEOPIXEL_COUNT=4
+    -D NUM_SCREENS=7