eventemitter should raise TypeError when there isn't enough arguments passed on emit (#293)

Author: theomonnom

.github/workflows/check-types.yml

@@ -29,7 +29,7 @@ jobs:
       run: python -m pip install --upgrade mypy 
 
     - name: Install packages 
-      run: python -m pip install ./livekit-api ./livekit-protocol ./livekit-rtc
+      run: python -m pip install pytest ./livekit-api ./livekit-protocol ./livekit-rtc
 
     - name: Check Types 
-      run: python -m mypy --install-type --non-interactive -p 'livekit-protocol' -p 'livekit-api' -p 'livekit-rtc'
+      run: python -m mypy --install-type --non-interactive -p 'livekit-protocol' -p 'livekit-api' -p 'livekit-rtc'

livekit-rtc/livekit/rtc/event_emitter.py

@@ -55,6 +55,8 @@ def greet(name):
                         callback_args = args[:num_args]
 
                         callback(*callback_args)
+                except TypeError:
+                    raise
                 except Exception:
                     logger.exception(f"failed to emit event {event}")
 

livekit-rtc/tests/test_emitter.py

@@ -0,0 +1,103 @@
+from livekit.rtc import EventEmitter
+from typing import Literal
+import pytest
+
+
+def test_events():
+    EventTypes = Literal["connected", "reconnected", "disconnected"]
+    emitter = EventEmitter[EventTypes]()
+
+    connected_calls = []
+
+    @emitter.once("connected")
+    def on_connected():
+        connected_calls.append(True)
+
+    emitter.emit("connected")
+    emitter.emit("connected")
+    assert len(connected_calls) == 1
+
+    emitter.emit("unknown_event")  # type: ignore
+
+    reconnected_calls = []
+
+    @emitter.on("reconnected")
+    def on_reconnected():
+        reconnected_calls.append(True)
+
+    emitter.emit("reconnected")
+    emitter.emit("reconnected")
+    assert len(reconnected_calls) == 2
+
+    disconnected_calls = []
+
+    @emitter.on("disconnected")
+    def on_disconnected():
+        disconnected_calls.append(True)
+
+    @emitter.on("disconnected")
+    def on_disconnected_another():
+        disconnected_calls.append(True)
+
+    emitter.emit("disconnected")
+    emitter.emit("disconnected")
+    emitter.off("disconnected", on_disconnected)
+    emitter.emit("disconnected")
+    assert len(disconnected_calls) == 5
+
+
+def test_args():
+    EventTypes = Literal["whatever"]
+
+    emitter = EventEmitter[EventTypes]()
+
+    calls = []
+
+    @emitter.on("whatever")
+    def on_whatever(first, second, third):
+        calls.append((first, second, third))
+
+    emitter.emit("whatever", 1, 2, 3)
+    emitter.emit("whatever", 1, 2, 3, 4, 5)  # only 3 arguments will be passed
+
+    assert len(calls) == 2
+    assert calls[0] == (1, 2, 3)
+    assert calls[1] == (1, 2, 3)
+
+    calls = []
+
+    with pytest.raises(TypeError):
+        emitter.emit("whatever", 1, 2)
+
+    assert len(calls) == 0
+
+    @emitter.on("whatever")
+    def on_whatever_varargs(*args):
+        calls.append(args)
+
+    emitter.emit("whatever", 1, 2, 3, 4, 5)
+
+    assert len(calls) == 2
+    assert calls[0] == (1, 2, 3)
+    assert calls[1] == (1, 2, 3, 4, 5)
+
+
+def test_throw():
+    EventTypes = Literal["error"]
+
+    emitter = EventEmitter[EventTypes]()
+
+    calls = []
+
+    @emitter.on("error")
+    def on_error():
+        calls.append(True)
+        raise ValueError("error")
+
+    @emitter.on("error")
+    def on_error_another():
+        calls.append(True)
+
+    emitter.emit("error")
+
+    assert len(calls) == 2