unix/coverage: Add coverage test for mp_sched_schedule_node.

Test modified to reschedule itself based on a flag setting. Without the
change in the parent commit, this test executes the callback indefinitely
and hangs but with the change it runs only once each time
mp_handle_pending() is called.

Modified-by: Angus Gratton <angus@redyak.com.au>
Signed-off-by: Andrew Leech <andrew.leech@planetinnovation.com.au>

ports/unix/coverage.c

@@ -184,6 +184,18 @@ static void pairheap_test(size_t nops, int *ops) {
     mp_printf(&mp_plat_print, "\n");
 }
 
+static mp_sched_node_t mp_coverage_sched_node;
+static bool coverage_sched_function_continue;
+
+static void coverage_sched_function(mp_sched_node_t *node) {
+    (void)node;
+    mp_printf(&mp_plat_print, "scheduled function\n");
+    if (coverage_sched_function_continue) {
+        // Re-scheduling node will cause it to run again next time scheduled functions are run
+        mp_sched_schedule_node(&mp_coverage_sched_node, coverage_sched_function);
+    }
+}
+
 // function to run extra tests for things that can't be checked by scripts
 static mp_obj_t extra_coverage(void) {
     // mp_printf (used by ports that don't have a native printf)
@@ -621,6 +633,19 @@ static mp_obj_t extra_coverage(void) {
             mp_obj_print_exception(&mp_plat_print, MP_OBJ_FROM_PTR(nlr.ret_val));
         }
         mp_handle_pending(true);
+
+        coverage_sched_function_continue = true;
+        mp_sched_schedule_node(&mp_coverage_sched_node, coverage_sched_function);
+        for (int i = 0; i < 3; ++i) {
+            mp_printf(&mp_plat_print, "loop\n");
+            mp_handle_pending(true);
+        }
+        // Clear this flag to prevent the function scheduling itself again
+        coverage_sched_function_continue = false;
+        // Will only run the first time through this loop, then not scheduled again
+        for (int i = 0; i < 3; ++i) {
+            mp_handle_pending(true);
+        }
     }
 
     // ringbuf

ports/unix/variants/coverage/mpconfigvariant.h

@@ -44,6 +44,7 @@
 #undef MICROPY_VFS_ROM_IOCTL
 #define MICROPY_VFS_ROM_IOCTL          (1)
 #define MICROPY_PY_CRYPTOLIB_CTR       (1)
+#define MICROPY_SCHEDULER_STATIC_NODES (1)
 
 // Enable os.uname for attrtuple coverage test
 #define MICROPY_PY_OS_UNAME            (1)

tests/ports/unix/extra_coverage.py.exp

@@ -122,6 +122,13 @@ unlocked
 KeyboardInterrupt: 
 KeyboardInterrupt: 
 10
+loop
+scheduled function
+loop
+scheduled function
+loop
+scheduled function
+scheduled function
 # ringbuf
 99 0
 98 1