introduce ifc with FIFOs

app/tests/test_byte_fifo.py

@@ -0,0 +1,43 @@
+# test_with_pytest.py
+
+from app.src.byte_fifo import ByteFifo
+
+def test_fifo():
+    read = ByteFifo()
+    assert 0 == len(read)
+    read += b'12'
+    assert 2 == len(read)
+    read += bytearray("34", encoding='UTF8')
+    assert 4 == len(read)
+    assert b'12' == read.peek(2)
+    assert 4 == len(read)
+    assert b'1234' == read.peek()
+    assert 4 == len(read)
+    assert b'12' == read.get(2)
+    assert 2 == len(read)
+    assert b'34' == read.get()
+    assert 0 == len(read)
+
+def test_fifo_fmt():
+    read = ByteFifo()
+    read += b'1234'
+    assert b'1234' == read.peek()
+    assert "  0000 | 31 32 33 34                                      | 1234" == f'{read}'
+
+def test_fifo_observer():
+    read = ByteFifo()
+
+    def _read():
+        assert b'1234' == read.get(4)
+
+    read += b'12'
+    assert 2 == len(read)
+    read()
+    read.reg_trigger(_read)
+    read += b'34'
+    assert 4 == len(read)
+    read()
+    assert 0 == len(read)
+    assert b'' == read.peek(2)
+    assert b'' == read.get(2)
+    assert 0 == len(read)