Allow compiling with Watchdog Timer calls

CHANGELOG.md

@@ -7,17 +7,18 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 ### Added
+- Allow use of watchdog timer in application code (though it doesn't do anything)
 - Show output from successful compile
 - `--min-free-space=N` command-line argument to fail if free space is below requred value
+- Add `_BV()` macro.
 
 ### Changed
 - Fix copy/paste error to allow additional warnings for a platform
 - Properly report compile errors in GitHub Actions (#296)
 - Put build artifacts in a separate directory to reduce clutter.
-- Change 266 files from CRLF to LF.
-- Add `_BV()` macro.
 - Replace `#define yield() _NOP()` with `inline void yield() { _NOP(); }` so that other code can define a `yield()` function.
 - Update .gitattributes so we have consistent line endings
+- Change 266 files from CRLF to LF.
 - Run tests on push as well as on a pull request so developers can see impact
 
 ### Deprecated

SampleProjects/TestSomething/test/wdt.cpp

@@ -0,0 +1,12 @@
+#include <Arduino.h>
+#include <ArduinoUnitTests.h>
+#include <avr/wdt.h>
+
+unittest(wdt) {
+  wdt_disable();
+  wdt_enable(WDTO_8S);
+  wdt_reset();
+  assertTrue(true);
+}
+
+unittest_main()

cpp/arduino/avr/wdt.h

@@ -0,0 +1,16 @@
+// Stub for testing that doesn't do anything (but at least compiles!)
+
+#define wdt_disable() (void)0
+#define wdt_enable(timeout) (void)0
+#define wdt_reset() (void)0
+
+#define WDTO_15MS 0
+#define WDTO_30MS 1
+#define WDTO_60MS 2
+#define WDTO_120MS 3
+#define WDTO_250MS 4
+#define WDTO_500MS 5
+#define WDTO_1S 6
+#define WDTO_2S 7
+#define WDTO_4S 8
+#define WDTO_8S 9