tests/extmod: Add test which subclasses framebuf.FrameBuffer.

tests/extmod/framebuf_subclass.py

@@ -0,0 +1,20 @@
+# test subclassing framebuf.FrameBuffer
+
+try:
+    import framebuf
+except ImportError:
+    print('SKIP')
+    raise SystemExit
+
+class FB(framebuf.FrameBuffer):
+    def __init__(self, n):
+        self.n = n
+        super().__init__(bytearray(2 * n * n), n, n, framebuf.RGB565)
+
+    def foo(self):
+        self.hline(0, 2, self.n, 0x0304)
+
+fb = FB(n=3)
+fb.pixel(0, 0, 0x0102)
+fb.foo()
+print(bytes(fb))

tests/extmod/framebuf_subclass.py.exp

@@ -0,0 +1 @@
+b'\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x03\x04\x03\x04\x03'