tests/micropython: Add test for yield-from while heap is locked.

tests/micropython/heapalloc_yield_from.py

@@ -0,0 +1,31 @@
+# Check that yield-from can work without heap allocation
+
+import micropython
+
+# Yielding from a function generator
+def sub_gen(a):
+    for i in range(a):
+        yield i
+def gen(g):
+    yield from g
+g = gen(sub_gen(4))
+micropython.heap_lock()
+print(next(g))
+print(next(g))
+micropython.heap_unlock()
+
+# Yielding from a user iterator
+class G:
+    def __init__(self):
+        self.value = 0
+    def __iter__(self):
+        return self
+    def __next__(self):
+        v = self.value
+        self.value += 1
+        return v
+g = gen(G())
+micropython.heap_lock()
+print(next(g))
+print(next(g))
+micropython.heap_unlock()

tests/micropython/heapalloc_yield_from.py.exp

@@ -0,0 +1,4 @@
+0
+1
+0
+1