Cannot test stdin with CliRunner, input does not seem to be propagated to the app correctly

[InCogNiTo124]

First Check

• I added a very descriptive title here.
• I used the GitHub search to find a similar question and didn't find it.
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• I already searched in Google "How to X in Typer" and didn't find any information.
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Example Code

## main.py

from pathlib import Path
from typing import List, Optional

import typer

app = typer.Typer()


def stdin_callback(value: Optional[Path]) -> List[Path]:
    return value if value else [Path("/dev/stdin")]

@app.command()
def main(
    files: List[Path] = typer.Argument(
        None,
        allow_dash=True,
        exists=True,
        dir_okay=False,
        readable=True,
        callback=stdin_callback,
        help="List of input files (default: stdin)",
        show_default=False,
    ),
):
    for f in files:
        text = f.read_text().split()
        print(','.join(reversed(text)))
    return

if __name__ == "__main__":
    app()



## test_main.py
from typer.testing import CliRunner

from main import app

runner = CliRunner()

def test_method():
    # FIXME input does not seem to be working ??
    result = runner.invoke(app, input=b"1\n2\n3\n5\n")
    assert result.exit_code == 0
    assert result.stdout == "5,3,2,1"

Description

The issue seems to be inability to test stdin with CliRunner.

To reproduce:

• create main.py with the contents as above.
• run python3 main.py.
• Type 1 and press return.
• Type 2 and press return.
• Type 3 and press return.
• Type 5 and press return.
• Press Ctrl+D.

Output: script outputs the numbers in the reverse order. this is a wanted behavior.

---

However I can't test this behaviour with CliRunner. To reproduce:

• Create test_main.py with the contents as above
• run pytest test_main.py
• it fails.

this is not a wanted behaviour

I tried looking into source code and on the github issues for the solutions or workarounds but I couldn't find anything connected to this.

Operating System

Linux

Operating System Details

Operating System: Manjaro Linux
KDE Plasma Version: 5.26.5
KDE Frameworks Version: 5.103.0
Qt Version: 5.15.8
Kernel Version: 6.1.12-1-MANJARO (64-bit)
Graphics Platform: X11
Processors: 20 × 13th Gen Intel® Core™ i5-13600K
Memory: 62.6 GiB of RAM
Graphics Processor: NVIDIA GeForce RTX 3090 Ti/PCIe/SSE2
Product Name: Z790 Pro RS

Typer Version

0.7.0

Python Version

Python 3.10.9

Additional Context

The main context is that I wish to make a CLI that does both of the following:

• if the CLI is not invoked with the argument, to read some lines from stdin. use case is in shell pipes, e.g. cat /dev/urandom | CLI
• if the CLI is invoked with the argument, it reads the lines from that argument

this is a standard behaviour of some unix tools, e.g. cat.

---

I tried to make a minimal Click reproducible example to verify this is indeed due to Typer but I have failed to do so; if someone else has enough knowledge I would appreciate it :))

[InCogNiTo124]

It's still unresolved with 0.9.0