If the object (message) is changed in consumes/produces functions, tester doesn't work properly.

[rjambrecic]

e.g.

class Currency(BaseModel):
    currency:` str = Field(..., description="Currency")

@app.consumes(prefix="on", topic="store_product")
async def on_store_product(msg: Currency):
    msg.currency = "EUR"
    
async with Tester(app).using_inmemory_broker() as tester:
    await tester.to_store_product(Currency(currency="HRK"))
    await app.awaited_mocks.on_store_product.assert_called_with(
        Currency(currency="HRK"),
        timeout=5
    )

assertion would fail:
AssertionError: expected call not found. Expected: mock(Currency(currency='HRK')) Actual: mock(Currency(currency='EUR'))

Quick fix: add at the beginning of each consumes/produces:
msg_copy = msg.model_copy()
and use the copy in the rest of the function...

Good fix: add msg.model_copy() to the Tester implementation

[davorrunje]

Why do you think creating a copy is a good idea? It is clearly overhead and not needed in most use cases. If needed, it is easy to create a copy in the body of the function.