Add c/hello-world

c/hello-world/test/test_hello_world.c

@@ -0,0 +1,27 @@
+#include <stddef.h>
+#include "vendor/unity.h"
+#include "../src/hello_world.h"
+
+void setUp(void)
+{
+}
+
+void tearDown(void)
+{
+}
+
+void test_hello(void)
+{
+   TEST_ASSERT_EQUAL_STRING("Hello, World!", hello());
+}
+
+int main(void)
+{
+   UnityBegin("test/test_hello_world.c");
+
+   RUN_TEST(test_hello);
+
+   UnityEnd();
+
+   return 0;
+}