fix program change send bug, add test

Author: todbot

README.rst

@@ -108,6 +108,12 @@ API documentation for this library can be found on `Read the Docs <https://circu
 For information on building library documentation, please check out
 `this guide <https://learn.adafruit.com/creating-and-sharing-a-circuitpython-library/sharing-our-docs-on-readthedocs#sphinx-5-1>`_.
 
+Testing
+=======
+
+Install `pytest` with `pip3 install pytest --upgrade` and run `pytest -v`
+
+
 Contributing
 ============
 

tests/__init__.py

@@ -0,0 +1,2 @@
+# SPDX-FileCopyrightText: Copyright (c) 2024 Tod Kurt
+# SPDX-License-Identifier: MIT

tests/test_tmidi_messages.py

@@ -0,0 +1,46 @@
+# SPDX-FileCopyrightText: Copyright (c) 2024 Tod Kurt
+# SPDX-License-Identifier: MIT
+
+
+import tmidi
+
+
+class PortStub:
+    def __init__(self, data):
+        self.data = data
+        self.expected = None
+
+    def write(self, buf, nbytes):
+        assert self.expected == list(buf)
+
+
+def test_message_note_on():
+    msg = tmidi.Message(tmidi.NOTE_ON, 64, 123)
+    assert str(msg) == "Message(NoteOn ch:0 64 123)"
+
+
+def test_message_program_change():
+    msg = tmidi.Message(tmidi.PROGRAM_CHANGE, 120, channel=11)
+    assert str(msg) == "Message(ProgramChange ch:11 120)"
+
+
+def test_message_note_on_send():
+    port = PortStub(iter([]))
+    midi_out = tmidi.MIDI(midi_out=port)
+
+    msg = tmidi.Message(tmidi.NOTE_ON, 64, 123)
+    port.expected = [0x90, 64, 123]
+    midi_out.send(msg)
+
+    msg = tmidi.Message(tmidi.NOTE_ON, 32, 111, channel=3)
+    port.expected = [0x93, 32, 111]
+    midi_out.send(msg)
+
+
+def test_message_program_change_send():
+    port = PortStub(iter([]))
+    midi_out = tmidi.MIDI(midi_out=port)
+
+    msg = tmidi.Message(tmidi.PROGRAM_CHANGE, 33)
+    port.expected = [0xC0, 33]
+    midi_out.send(msg)

tests/test_tmidi_one.py

@@ -32,7 +32,7 @@ def readinto(self, buf, numbytes=1):
 
         return bytes_read
 
-    def write(self, buf):
+    def write(self, buf, n):
         pass
 
 

tmidi.py

@@ -174,14 +174,14 @@ class Message:
     MIDI Message.
 
     :param mtype: The type of message, e.g. tmidi.NOTE_ON.
-    :param channel: The MIDI channel for this message, if applicable (0-15)
     :param data0: The first data byte for this message,
         e.g. the note number as an ``int`` (0-127) for NOTE_ON messages.
     :param data1: The second data byte for this message,
         e.g. the velocity (0-127) for NOTE_ON messages.
+    :param channel: The MIDI channel for this message, if applicable (0-15)
     """
 
-    def __init__(self, mtype=SYSTEM_RESET, channel=None, data0=0, data1=0):
+    def __init__(self, mtype=SYSTEM_RESET, data0=0, data1=0, channel=0):
         """
         Create a MIDI Message.
 
@@ -204,9 +204,9 @@ def __bytes__(self):
         status_byte = self.type
         if _is_channel_message(status_byte):
             status_byte |= self.channel
-        if status_byte in _LEN_2_MESSAGES:
+        if self.type in _LEN_2_MESSAGES:
             return bytes([status_byte, self.data0, self.data1])
-        if status_byte in _LEN_1_MESSAGES:
+        elif self.type in _LEN_1_MESSAGES:
             return bytes([status_byte, self.data0])
         return bytes([status_byte])